REFRIGERATOR AND METHOD FOR CONTROLLING THE SAME

Abstract

A refrigerator is provided. The refrigerator includes a storage compartment, an evaporator, a compressor, a first electrode arranged in the storage compartment, a second electrode arranged spaced apart from the first electrode in the storage compartment, a radio frequency (RF) power supply configured to apply an RF signal to the first electrode and the second electrode, a voltage control circuit configured to adjust an input voltage of the RF power supply, a frequency control circuit configured to generate a switching signal for turning the RF power supply on or off, a voltage-current detector configured to detect an output voltage between the first electrode and the second electrode and an output current of the first electrode, memory storing instructions, and at least one processor operatively couple to the compressor, the at least one voltage control circuit, the frequency control circuit, the voltage-current detector, and the memory, wherein the instructions, when executed by the at least one processor individually or collectively, cause the refrigerator to operate the compressor, identify an impedance change rate of food placed between the first electrode and the second electrode based on the output voltage and the output current, and adjust a reference voltage applied to the at least one voltage control circuit or an on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food.

Claims

1. A refrigerator, comprising: a storage compartment; an evaporator configured to cool the storage compartment; a compressor configured to supply a refrigerant to the evaporator; a first electrode arranged in the storage compartment; a second electrode arranged spaced apart from the first electrode in the storage compartment; a radio frequency (RF) power supply configured to apply an RF signal to the first electrode and the second electrode; at least one voltage control circuit configured to adjust an input voltage of the RF power supply; a frequency control circuit configured to generate a switching signal for turning the RF power supply on or off; a voltage-current detector configured to detect an output voltage between the first electrode and the second electrode and an output current of the first electrode; memory storing instructions; and at least one processor operatively couple to the compressor, the at least one voltage control circuit, the frequency control circuit, the voltage-current detector, and the memory, wherein the instructions, when executed by the at least one processor individually or collectively, cause the refrigerator to: operate the compressor to cool the storage compartment, identify an impedance change rate of food placed between the first electrode and the second electrode based on the output voltage and the output current periodically detected by the voltage-current detector, and adjust a reference voltage applied to the at least one voltage control circuit or an on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food.

2. The refrigerator of claim 1, wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to: adjust the reference voltage applied to the at least one voltage control circuit, based on the impedance change rate of the food being greater than or equal to a reference value, and adjust the on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food being less than the reference value.

3. The refrigerator of claim 2, wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to: reduce the reference voltage to reduce the input voltage, and reduce the on-off duty ratio of the frequency control circuit, based on a decrease in the impedance change rate of the food.

4. The refrigerator of claim 2, wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to: adjust a frequency of the switching signal, based on the impedance change rate of the food being less than the reference value.

5. The refrigerator of claim 4, wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to: reduce the frequency of the switching signal, based on a decrease in the impedance change rate of the food.

6. The refrigerator of claim 2, wherein the reference value is a first reference value, and wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to: maintain the on-off duty ratio of the frequency control circuit to be constant, based on the impedance change rate of the food being within an error range of a second reference value that is less than the first reference value.

7. The refrigerator of claim 2, wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to: apply the reference voltage to the at least one voltage control circuit to generate an electric field between the first electrode and the second electrode, based on the impedance change rate of the food being less than or equal to a threshold value after the compressor starts operating, and wherein the threshold value is greater than the reference value.

8. The refrigerator of claim 1, further comprising: a food sensor configured to identify the food, wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to: obtain food information corresponding to the identified food and electric field control information corresponding to the food information from the memory or a user device, and determine the on-off duty ratio of the frequency control circuit or the reference voltage applied to the at least one voltage control circuit based on the electric field control information.

9. The refrigerator of claim 1, further comprising: a direct current (DC) converter configured to apply a voltage to the RF power supply; and a power factor correction (PFC) circuit configured to deliver power factor compensated power to the DC converter, wherein the at least one voltage control circuit is connected to at least one of the DC converter or the PFC circuit.

10. The refrigerator of claim 1, further comprising: an impedance matching circuit through which the RF power supply applies the RF signal to the first electrode and the second electrode, wherein the instructions, when executed by the at least one processor individually or collectively, further cause the refrigerator to: control the impedance matching circuit to match an output impedance of the RF power supply and an electrode impedance of the first electrode and the second electrode.

11. A method performed by a refrigerator comprising a storage compartment, an evaporator configured to cool the storage compartment, a compressor configured to supply a refrigerant to the evaporator, a first electrode arranged in the storage compartment, a second electrode arranged spaced apart from the first electrode in the storage compartment, a radio frequency (RF) power supply configured to apply an RF signal to the first electrode and the second electrode, a direct current (DC) converter configured to apply a voltage to the RF power supply, and a power factor correction (PFC) circuit configured to deliver power factor compensated power to the DC converter, the method comprising: operating the compressor to supply the refrigerant to the evaporator so as to cool the storage compartment; identifying an impedance change rate of food placed between the first electrode and the second electrode, based on an output voltage between the first electrode and the second electrode and an output current of the first electrode, the output voltage and the output current being periodically detected by a voltage-current detector; and adjusting a reference voltage applied to at least one voltage control circuit configured to adjust an input voltage of the RF power supply, or an on-off duty ratio of a frequency control circuit configured to generate a switching signal for turning the RF power supply on or off, based on the impedance change rate of the food.

12. The method of claim 11, wherein the adjusting of the reference voltage or the on-off duty ratio comprises: adjusting the reference voltage applied to the at least one voltage control circuit, based on the impedance change rate of the food being greater than or equal to a reference value; and adjusting the on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food being less than the reference value.

13. The method of claim 12, wherein the adjusting of the reference voltage comprises reducing the reference voltage to reduce the input voltage, based on a decrease in the impedance change rate of the food, and wherein the adjusting of the on-off duty ratio comprises reducing the on-off duty ratio based on the decrease in the impedance change rate of the food.

14. The method of claim 12, further comprising: adjusting a frequency of the switching signal, based on the impedance change rate of the food being less than the reference value.

15. The method of claim 14, wherein the adjusting of the frequency of the switching signal comprises reducing the frequency of the switching signal based on a decrease in the impedance change rate of the food.

16. The method of claim 12, wherein the reference value is a first reference value, and wherein the adjusting of the on-off duty ratio comprises maintaining the on-off duty ratio of the frequency control circuit to be constant based on the impedance change rate of the food being within an error range of a second reference value that is less than the first reference value.

17. The method of claim 12, further comprising: applying the reference voltage to the at least one voltage control circuit to generate an electric field between the first electrode and the second electrode, based on the impedance change rate of the food being less than or equal to a threshold value after the compressor starts operating, wherein the threshold value is greater than the reference value.

18. The method of claim 11, further comprising: identifying, by a food sensor of the refrigerator, the food; and obtaining food information corresponding to the identified food and electric field control information corresponding to the food information from memory or the refrigerator or a user device, wherein the adjusting of the reference voltage or the on-off duty ratio includes determining the on-off duty ratio of the frequency control circuit or the reference voltage applied to the at least one voltage control circuit based on the electric field control information.

19. The method of claim 11, wherein the at least one voltage control circuit is connected to at least one of the DC converter or the PFC circuit.

20. The method of claim 11, further comprising: controlling an impedance matching circuit of the refrigerator, through which the RF power supply applies the RF signal to the first electrode and the second electrode, to match an output impedance of the RF power supply and an electrode impedance of the first electrode and the second electrode.

Description

DESCRIPTION OF DRAWINGS

[0017] The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0018] FIG. 1 is a perspective view of a refrigerator with an open door according to an embodiment of the disclosure;

[0019] FIG. 2 is a side cross-sectional view of a refrigerator according to an embodiment of the disclosure;

[0020] FIG. 3 is a control block diagram of a refrigerator according to an embodiment of the disclosure;

[0021] FIG. 4 illustrates a circuit system for dielectric heating of food according to an embodiment of the disclosure;

[0022] FIGS. 5 and 6 illustrate a detailed circuit structure of the circuit system of FIG. 4 according to various embodiments of the disclosure;

[0023] FIG. 7 illustrates a circuit system for dielectric heating of food according to an embodiment of the disclosure;

[0024] FIG. 8 illustrate a detailed circuit structure of the circuit system of FIG. 7 according to an embodiment of the disclosure;

[0025] FIG. 9 illustrates a circuit system for dielectric heating of food according to an embodiment of the disclosure;

[0026] FIG. 10 illustrates an example of a switching signal output by a frequency control circuit according to an embodiment of the disclosure;

[0027] FIG. 11 is an example of a graph showing a change in food temperature and a change in food impedance in a non-freezing mode according to an embodiment of the disclosure;

[0028] FIG. 12 is another example of a graph showing a change in food temperature in a non-freezing mode according to an embodiment of the disclosure;

[0029] FIG. 13 is an example of a graph showing a change in food temperature in a refrigerating mode according to an embodiment of the disclosure;

[0030] FIG. 14 is an example of a graph showing a change in food temperature in a defrost mode according to an embodiment of the disclosure;

[0031] FIG. 15 is a flowchart illustrating a method performed by a refrigerator according to an embodiment of the disclosure;

[0032] FIG. 16 is a flowchart illustrating the method performed by a refrigerator of FIG. 15 in more detail according to an embodiment of the disclosure; and

[0033] FIG. 17 is a flowchart illustrating addible operations to the method performed by a refrigerator of FIG. 15 according to an embodiment of the disclosure.

[0034] The same reference numerals are used to represent the same elements throughout the drawings.

MODES OF THE DISCLOSURE

[0035] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

[0036] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

[0037] It is to be understood that the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a component surface includes reference to one or more of such surfaces.

[0038] In describing of the drawings, similar reference numerals may be used for similar or related elements.

[0039] The singular form of a noun corresponding to an item may include one or more of the items unless clearly indicated otherwise in a related context.

[0040] In the disclosure, phrases, such as A or B, at least one of A and B, at least one of A or B, A, B or C, at least one of A, B and C, and at least one of A, B, or C may include any one or all possible combinations of the items listed together in the corresponding phrase among the phrases.

[0041] As used herein, the term and/or includes any and all combinations of one or more of the associated listed items.

[0042] Terms such as 1st, 2nd, primary, or secondary may be used simply to distinguish an element from other elements, without limiting the element in other aspects (e.g., importance or order).

[0043] Further, as used in the disclosure, the terms front, rear, top, bottom, side, left, right, upper, lower, and the like are defined with reference to the drawings, and are not intended to limit the shape and position of any element.

[0044] It will be understood that when the terms includes, comprises, including, and/or comprising are used in the disclosure, they specify the presence of the specified features, figures, steps, operations, components, members, or combinations thereof, but do not preclude the presence or addition of one or more other features, figures, steps, operations, components, members, or combinations thereof.

[0045] When a given element is referred to as being connected to, coupled to, supported by or in contact with another element, it is to be understood that it may be directly or indirectly connected to, coupled to, supported by, or in contact with the other element. When a given element is indirectly connected to, coupled to, supported by, or in contact with another element, it is to be understood that it may be connected to, coupled to, supported by, or in contact with the other element through a third element.

[0046] It will also be understood that when an element is referred to as being on another element, it may be directly on the other element or intervening elements may also be present.

[0047] When an element (e.g., a first element) is referred to as being (functionally or communicatively) coupled or connected to another element (e.g., a second element), the first element may be connected to the second element, directly (e.g., wired), wirelessly, or through a third element.

[0048] A refrigerator according to an embodiment of the disclosure may include a cabinet.

[0049] The cabinet may include an inner case, an outer case positioned outside the inner case, and an insulation provided between the inner case and the outer case.

[0050] The inner case may include a case, a plate, a panel, or a liner forming a storage compartment. The inner case may be formed as one body, or may be formed by assembling a plurality of plates together. The outer case may form an appearance of the cabinet, and be coupled to an outer side of the inner case such that the insulation is positioned between the inner case and the outer case.

[0051] The insulation may insulate an inside of the storage compartment from an outside of the storage compartment to maintain inside temperature of the storage compartment at appropriate temperature without being influenced by an external environment of the storage compartment. According to an embodiment of the disclosure, the insulation may include a foaming insulation. The foaming insulation may be molded by fixing the inner case and the outer case with jigs, etc. And then injecting and foaming urethane foam as a mixture of polyurethane and a foaming agent between the inner case and the outer case.

[0052] According to an embodiment of the disclosure, the insulation may include a vacuum insulation in addition to a foaming insulation, or may be configured only with a vacuum insulation instead of a forming insulation. The vacuum insulation may include a core material and a cladding material accommodating the core material and sealing the inside with vacuum or pressure close to vacuum. However, the insulation is not limited to the above-mentioned foaming insulation or vacuum insulation, and may include various materials capable of being used for insulation.

[0053] The storage compartment may include a space defined by the inner case. The storage compartment may further include the inner case defining the space corresponding to the storage compartment. The storage compartment may store a variety of items, such as food, medicines, cosmetics, and the like, and the storage compartment may be configured to be open on at least one side for insertion and removal of the items.

[0054] The refrigerator 1 may include one or more storage compartments. In a case in which two or more storage compartments are formed in the refrigerator, the respective storage compartments may have different purposes of use, and may be maintained at different temperatures. To this end, the respective storage compartments may be partitioned by a partition wall including an insulation.

[0055] The storage compartment may be maintained within an appropriate temperature range according to a purpose of use, and may include a refrigerating compartment, a freezing compartment, and a temperature conversion compartment according to purposes of use and/or temperature ranges. The refrigerating compartment may be maintained at an appropriate temperature to keep food refrigerating, and the freezing compartment may be maintained at an appropriate temperature to keep food frozen. The refrigerating may be keeping food cold without freezing the food, and for example, the refrigerating compartment may be maintained within a range of 0 degrees Celsius to 7 degrees Celsius. The freezing may be freezing food or keeping food frozen, and for example, the freezing compartment may be maintained within a range of 20 degrees Celsius to 1 degrees Celsius. The temperature conversion compartment may be used as either a refrigerating compartment or a freezing compartment according to or regardless of a user's selection.

[0056] The storage compartment may also be referred to by various terms, such as vegetable compartment, freshness compartment, cooling compartment, and ice-making compartment, in addition to refrigerating compartment, freezing compartment, and temperature conversion compartment, and the terms, such as refrigerating compartment, freezing compartment, temperature conversion compartment, etc., as used below are to be understood as representing storage compartments having the corresponding purposes of use and the corresponding temperature ranges.

[0057] The refrigerator 1 according to an embodiment of the disclosure may include at least one door configured to open or close the open side of the storage compartment. The respective doors may be provided to open and close one or more storage compartments, or a single door may be provided to open and close a plurality of storage compartments. The door may be rotatably or slidably mounted to the front of the cabinet.

[0058] The door may seal the storage compartment in a closed state. The door, like the cabinet, may include an insulation to insulate the storage compartment in a closed state.

[0059] According to an embodiment, the door may include an outer door plate forming the front surface of the door, an inner door plate forming the rear surface of the door and facing the storage compartment, an upper cap, a lower cap, and a door insulation provided therein.

[0060] A gasket may be provided on the edge of the inner door plate to seal the storage compartment by coming into close contact with the front surface of the cabinet when the door is closed. The inner door plate may include a dyke that protrudes rearward to allow a door basket for storing items to be fitted.

[0061] According to an embodiment, the door may include a door body and a front panel that is detachably coupled to the front of the door body and forming the front surface of the door. The door body may include an outer door plate forming the front surface of the door body, an inner door plate forming the rear surface of the door body and facing the storage compartment, an upper cap, a lower cap, and a door insulator provided therein.

[0062] The refrigerator 1 may be classified as French Door Type, Side-by-side Type, Bottom Mounted Freezer (BMF), Top Mounted Freezer (TMF), or Single Door Refrigerator according to the arrangement of the doors and the storage compartments.

[0063] The refrigerator 1 according to an embodiment of the disclosure may include a cold air supply device for supplying cold air to the storage compartment.

[0064] The cold air supply device may include a machine, an apparatus, an electronic device, and/or a combination system thereof, capable of generating cold air and guiding the cold air to cool the storage compartment.

[0065] According to an embodiment of the disclosure, the cold air supply device may generate cold air through a cooling cycle including compression, condensation, expansion, and evaporation processes of refrigerants. To this end, the cold air supply device may include a cooling cycle system having a compressor, a condenser, an expander, and an evaporator to drive the refrigeration cycle. According to an embodiment of the disclosure, the cold air supply device may include a semiconductor, such as a thermoelectric element. The thermoelectric element may cool the storage compartment by heating and cooling actions through the Peltier effect.

[0066] The refrigerator 1 according to an embodiment of the disclosure may include a machine compartment in which at least some components belonging to the cold air supply device are installed.

[0067] The machine compartment may be partitioned and insulated from the storage compartment to prevent heat generated by the components installed in the machine compartment from being transferred to the storage compartment. To dissipate heat from the components installed in the machine compartment, the machine compartment may communicate with outside of the cabinet.

[0068] The refrigerator 1 according to an embodiment of the disclosure may include a dispenser provided on the door to provide water and/or ice. The dispenser may be provided on the door to allow access by the user without opening the door.

[0069] The refrigerator 1 according to an embodiment of the disclosure may include an ice-making device that produces ice. The ice-making device may include an ice-making tray that stores water, an ice-moving device that separates ice from the ice-making tray, and an ice-bucket that stores ice produced in the ice-making tray.

[0070] The refrigerator 1 according to an embodiment of the disclosure may include a controller for controlling the refrigerator 1. The refrigerator 1 may include at least one controller. The controller may generate a control signal for controlling the operation of the cold air supply device. For example, the controller may receive temperature information of the storage compartment from a temperature sensor, and generate a cooling control signal for controlling the operation of the cold air supply device based on the temperature information of the storage compartment.

[0071] Hereinafter, various embodiments according to the disclosure will be described in detail with reference to the accompanying drawings.

[0072] It should be appreciated that the blocks in each flowchart and combinations of the flowcharts may be performed by one or more computer programs which include instructions. The entirety of the one or more computer programs may be stored in a single memory device or the one or more computer programs may be divided with different portions stored in different multiple memory devices.

[0073] Any of the functions or operations described herein can be processed by one processor or a combination of processors. The one processor or the combination of processors is circuitry performing processing and includes circuitry like an application processor (AP, e.g. a central processing unit (CPU)), a communication processor (CP, e.g., a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a wireless fidelity (Wi-Fi) chip, a Bluetooth chip, a global positioning system (GPS) chip, a near field communication (NFC) chip, connectivity chips, a sensor controller, a touch controller, a finger-print sensor controller, a display driver integrated circuit (IC), an audio CODEC chip, a universal serial bus (USB) controller, a camera controller, an image processing IC, a microprocessor unit (MPU), a system on chip (SoC), an IC, or the like.

[0074] FIG. 1 is a perspective view of a refrigerator with an open door according to an embodiment of the disclosure.

[0075] FIG. 2 is a side cross-sectional view of a refrigerator according to an embodiment of the disclosure.

[0076] Referring to FIGS. 1 and 2, the refrigerator 1 may include a cabinet 10, a storage compartment 20 formed by being vertically divided inside the cabinet 10, and a door 30 for opening and closing the storage compartment 20. In addition, the refrigerator 1 may include a cold air supply device for supplying cold air to the storage compartment 20.

[0077] The cabinet 10 may include an inner case 11 forming the storage compartment 20, an outer case 12 coupled to the outer side of the inner case 11 to form an outer appearance, and an insulation 13 foamed between the inner case 11 and the outer case 12 to insulate the storage compartment 20.

[0078] The storage compartment 20 may be divided into a plurality of storage compartments 22, 23, and 24 by the partitions 15. For example, the storage compartment 20 may be divided into a plurality of storage compartments 22, 23, and 24 by the partitions 15. The partitions 15 may include a first partition 17 and a second partition 19. When the first partition 17 and the second partition 19 are combined, the partitions 15 may have a T-shape. The partitions 15 may divide the storage compartment 20 into three spaces.

[0079] The first partition 17 may horizontally divide the storage compartment 20 into an upper storage compartment 22 and lower storage compartments 23 and 24. The second partition 19 may vertically divide the lower storage compartments 23 and 24 into the first storage compartment 23 and the second storage compartment 24. The upper storage compartment 22 may be used as a refrigerating compartment. At least one of the two lower storage compartments 23 and 24 may be used as a freezing compartment.

[0080] For example, both the first lower storage compartment 23 and the second lower storage compartment 24 may be used as a freezing compartment. The first lower storage compartment 23 may be used as a freezing compartment and the second lower storage compartment 24 may be used as a refrigerating compartment. The first lower storage compartment 23 may be used as a freezing compartment and the second lower storage compartment 24 may be used as a refrigerating compartment. Both the first lower storage compartment 23 and the second lower storage compartment 24 may be used as a refrigerating compartment.

[0081] The storage compartment 20 is not limited to the above examples. The storage compartment 20 may be formed in various ways depending on the design. Inside the storage compartment 20, a plurality of shelves 25 and storage containers 26 and 36 may be provided to store food, and the like. A plurality of storage containers 26 and 36 may be provided. Each of the plurality of storage containers 26 and 36 may be defined as the storage compartment. For example, a single storage container may be described as a single storage compartment. The first storage container 26 may be provided in the upper storage compartment 22, and the second storage containers 36 may be provided in the lower storage compartments 23 and 24. The plurality of shelves 25 may divide a single storage compartment into a plurality of accommodation spaces. In addition, the storage containers 26 and 36 may each be placed in the accommodation space.

[0082] The refrigerator 1 may include the door 30. The door 30 may open or close each of the upper storage compartment 22 and the lower storage compartments 23 and 24. The door 30 may be rotatably coupled to the cabinet 10. The door 30 may include a pair of upper doors 31 and a pair of lower doors 33. The upper doors 31 may open and close the upper storage compartment 22. The lower doors 33 may open and close the lower storage compartments 23 and 24.

[0083] The pair of upper doors 31 may have a handle 32 including a first door handle 32a and a second door handle 32b. At least one of the upper doors 31 may open or close a portion of the upper storage compartment 22 or the entire upper storage compartment 22. The pair of lower doors 33 may be provided with a freezing compartment door handle 34. The lower doors 33 may be provided as sliding doors.

[0084] A rotating bar 35 may be provided on at least one of the pair of upper doors 31 to seal a gap between the upper doors 31 when the upper doors 31 are closed. The rotating bar 35 may be rotatably coupled to at least one of the pair of upper doors 31. The rotating bar 35 may be rotated by a rotating guide 14 formed on the cabinet 10 according to the opening and closing of the upper doors 31.

[0085] Door shelves 31a and 33a for storing food may be arranged on the back side of the upper doors 31 and the lower doors 33. Shelf supports 31b and 33b for supporting the left and right sides of the door shelves 31a and 33a may be arranged on each of the upper doors 31 and the lower doors 33. The shelf supports 31b and 33b may be detachable from each of the doors 31 and 33.

[0086] First gaskets 31c and 33c may be provided on the edge of the back side of each of the upper doors 31 and the lower doors 33 to seal the gap between the doors 31 and 33 and the cabinet 10 in a state where the doors are closed. The first gaskets 31c and 33c may be installed in a loop shape along the edge of the back side of each of the doors 31 and 33, and may include a magnet inside.

[0087] The upper doors 31 may be provided as a double door including a first door 40 and a second door 50. The first door 40 may be rotatably coupled to the cabinet 10 by a hinge and may open and close the upper storage compartment 22. The door shelf 31a, the shelf support 31b, and the first gasket 31c described above may be provided on the first door 40.

[0088] The first door 40 may include an opening 41. A user may store food in the door shelf 31a or take food out from the door shelf 31a through the opening 41 in a state where the first door 40 is closed. The opening 41 passes through the first door 40 and may be opened and closed by the second door 50.

[0089] The second door 50 may be provided on the front of the first door 40 so as to open and close the opening 41 of the first door 40. The second door 50 may be rotatable in the same direction as the first door 40. For example, the second door 50 may be rotatably supported by a hinge installed on the first door 40. The hinge may also be installed on the cabinet 10.

[0090] The second door 50 may include a second gasket for maintaining airtightness with the first door 40. The second gasket may be installed in a loop shape along the edge of the back side of the second door 50, and may include a magnet inside.

[0091] The machine compartment 27 may be formed at a lower rear side of the cabinet 10. A cooling cycle system may be disposed in the machine compartment 27. The cooling cycle system may include a compressor 70 for compressing a refrigerant, a condenser for condensing the refrigerant, an expansion device (expander) for expanding the refrigerant condensed by the condenser, evaporators 81 and 82 installed behind the storage compartment 20 to cool the surrounding air, and fans F2 and F3 that move the air cooled by the evaporators 81 and 82 to the storage compartment 20. The refrigerator 1 may include cold air ducts 61 and 62 for guiding the cold air flowing according to the operation of the fan F2 and F3 to the storage compartment 20. The cold air ducts 61 and 62 may be disposed on the rear side of the storage compartment 20.

[0092] The first cold air duct 61, the first evaporator 81, and the first fan F1 may be disposed behind the upper storage compartment 22. The air cooled by the first evaporator 81 may move to the upper storage compartment 22 through the first cold air duct 61 according to the operation of the first fan F1. The second cold duct 62, the second evaporator 82, and the second fan F2 may be disposed behind the lower storage compartments 23 and 24. The air cooled by the second evaporator 82 may move to the lower storage compartments 23 and 24 through the second cold duct 62 according to the operation of the second fan F2.

[0093] A plurality of electrodes 90 may be arranged in the storage compartment 20. The plurality of electrodes 90 may be spaced apart and be arranged in parallel. For example, the refrigerator 1 may include a first electrode 90a and a second electrode 90b disposed in the lower storage compartments 23 and 24. The first electrode 90a and the second electrode 90b may be spaced apart from each other and may be arranged in parallel. The first electrode 90a and the second electrode 90b may be arranged facing each other. The first electrode 90a may be located above the second electrode 90b. The first electrode 90a and the second electrode 90b may be parallel to the upper and lower surface of the storage compartment 20. The first electrode 90a and the second electrode 90b may each be included in the shelf. The first electrode 90a and the second electrode 90b may be fixed or detachable from the inner case 11.

[0094] The number and location of the electrodes 90 are not limited to the above examples. For example, three or more electrodes may be spaced apart and be arranged in parallel within the lower storage compartments 23 and 24. In the upper storage compartment 22, the plurality of electrodes 90 may be spaced apart and be arranged in parallel. In addition, a length, an area and/or a thickness of the electrode 90 may vary depending on the design.

[0095] Each of the plurality of electrodes 90 may be electrically connected to a radio frequency (RF) power supply 140 to be described below. When an RF signal is applied to the plurality of electrodes 90, an electric field may be generated between the first electrode 90a and the second electrode 90b. The electric field may cause dielectric materials (e.g., water molecules) contained in the food to oscillate. As the dielectric materials (e.g., water molecules) oscillate, molecular friction generates heat, thereby heating the dielectric materials.

[0096] Food may be placed between the first electrode 90a and the second electrode 90b. For example, the first electrode 90a and the second electrode 90b may divide the storage compartment 20 into a plurality of accommodation spaces. Food may be placed in a space between the first electrode 90a and the second electrode 90b. The storage containers 26 and 36 containing food may be disposed between the first electrode 90a and the second electrode 90b. An electric field generated between the first electrode 90a and the second electrode 90b may heat the food. A temperature of the food placed between the first electrode 90a and the second electrode 90b may be adjusted independently of the temperature of the storage compartment 20.

[0097] A polarity of each of the plurality of electrodes 90 may be determined according to a phase of the RF signal applied to each of the plurality of electrodes 90. An electric field may or may not be generated between the plurality of electrodes 90 depending on the polarity of each of the plurality of electrodes 90. A magnitude of the electric field generated between the plurality of electrodes 90 may vary depending on a magnitude of the RF signal applied to the plurality of electrodes 90. For example, the polarity of the first electrode 90a may be positive (+) and the polarity of the second electrode 90b may be negative (). In this case, the second electrode 90b may correspond to a ground electrode, and an electric field may be generated between the first electrode 90a and the second electrode 90b.

[0098] FIG. 3 is a control block diagram of a refrigerator according to an embodiment of the disclosure.

[0099] Referring to FIG. 3, the refrigerator 1 may include a controller 300. The controller 300 may include a processor 320 and memory 310. The memory 310 may include a volatile memory (e.g., static random access memory (S-RAM), dynamic random access memory (D-RAM)) and a non-volatile memory (e.g., read only memory (ROM), erasable programmable read only memory (EPROM)). The processor 320 and memory 310 may be implemented as separate chips or may be implemented as a single chip. In addition, a plurality of processors and a plurality of memories may be provided.

[0100] The controller 300 and/or the processor 320 may be electrically connected to various electronic devices and/or electronic components of the refrigerator 1, and may control the electronic devices and/or electronic components. The controller 300 and/or the processor 320 may control operation of the refrigerator 1.

[0101] The processor 320 may process various data and signals using instructions, data, programs, and/or software stored in the memory 310. The processor 320 may generate a control signal for controlling the components of the refrigerator 1. The processor 320 may include a single core or a plurality of cores.

[0102] The processor 320 may be configured to perform various operations of the refrigerator 1. The processor 320 may perform the operation of the refrigerator 1 according to various embodiments by executing at least one instruction, algorithm, program, and/or software stored in the memory 310. The processor 320 may control one or any combination of the components of the refrigerator 1. The processor 320 may include a main processor and at least one sub processor. Various electronic devices and/or electronic components of the refrigerator 1 may be controlled by separate processors or by one integrated processor.

[0103] The processor 320 may include a variety of circuits (circuitries). For example, the processor 320 may include at least one of a central processing unit (CPU), graphics processing unit (GPU), accelerated processing unit (APU), many integrated core (MIC), digital signal processor (DSP), neural processing unit (NPU), hardware accelerator, or machine learning accelerator.

[0104] The refrigerator 1 according to the disclosure may include a cooling cycle system for cooling the storage compartment 20 and a circuit system for dielectric heating of food. The refrigerator 1 may independently perform the cooling of the storage compartment 20 and the heating of the food. The refrigerator 1 may directly heat the food by applying an electric field to the food placed in the storage compartment 20 while cooling the storage compartment 20. Accordingly, the refrigerator 1 may store the food at different temperatures and precisely adjust the temperature of the food.

[0105] The cooling cycle system may include the compressor 70 for compressing a refrigerant, the condenser for condensing the refrigerant, a flow path switching valve 74 for switching a flow path of refrigerant discharged from the condenser, the expansion device for expanding the refrigerant condensed by the condenser, the first evaporator 81 for cooling the air supplied to the upper storage compartment 22, the second evaporator 82 for cooling the air supplied to the lower storage compartments 23 and 24, the first fan F1 for moving the cooled air to the upper storage compartment 22, the second fan F2 for moving the cooled air to the lower storage compartments 23 and 24, and the third fan F3 for supplying the air to the condenser.

[0106] The compressor 70 may draw the refrigerant and compress the drawn refrigerant to convert the compressed refrigerant into high-temperature, high-pressure gaseous refrigerant. The refrigerant may be drawn in by using a rotational force of an embedded motor. The compressor 70 may compress the low-temperature, low-pressure refrigerant and discharge the high-temperature, high-pressure refrigerant. The refrigerant may be discharged from the compressor 70 in a gaseous state. The refrigerant may be circulated in the refrigeration cycle by drawing in and discharging the refrigerant by the compressor 70.

[0107] The high-temperature, high-pressure refrigerant discharged from the compressor 70 may flow to the condenser. The condenser may be connected to an outlet of the compressor 70 and may condense the gaseous refrigerant, discharged from the compressor 70, into a liquid by heat exchange with the surrounding air. As the refrigerant liquefies in the condenser, the refrigerant releases heat to the outside, thereby lowering a temperature of the refrigerant.

[0108] The processor 320 may adjust an operating frequency and/or revolution per minute (RPM) of the compressor 70. As the operating frequency and/or RPM of the compressor 70 increases, the heat released around the condenser may increase.

[0109] The flow path switching valve 74 may switch the flow path of the refrigerant discharged from the condenser according to an operation mode (e.g., refrigerating mode or freezing mode) of the refrigerator 1. The processor 320 may control the flow path switching valve 74 to guide the refrigerant to the first evaporator 81 or the second evaporator 82 according to an operation mode (e.g., refrigerating mode or freezing mode) of the refrigerator 1. The flow path switching valve 74 may guide the refrigerant discharged from the condenser to the first evaporator 81 or the second evaporator 82. During a refrigerating operation for cooling the upper storage compartment 22, the flow path switching valve 74 may guide the refrigerant to the first evaporator 81. During a freezing operation for cooling the lower storage compartments 23 and 24, the flow path switching valve 74 may guide the refrigerant to the second evaporator 82. The refrigerating operation for cooling the upper storage compartment 22 and the freezing operation for cooling the lower storage compartments 23 and 24 may be performed independently using the flow path switching valve 74.

[0110] The expansion device may include a refrigerating compartment expansion device and a freezing compartment expansion device. The expansion device may expand the liquid refrigerant flowing from the flow path switching valve 74. A temperature and pressure of the refrigerant may be lowered while passing through the expansion device. The refrigerant expanded in the expansion device may be a two-phase refrigerant including a liquid component and a gas component.

[0111] The expansion device may be provided as an expansion valve. The expansion valve may be a thermoelectric electronic expansion valve that uses deformation of a bimetal, a thermostatic electronic expansion valve that uses volumetric expansion by heating enclosed wax, a pulse width modulation type electronic expansion valve for opening or closing a solenoid valve according to a pulse signal, or a step motor type electronic expansion valve that uses a motor to open or close the valve.

[0112] The expansion device may be formed as a capillary tube. The capillary tube may be implemented by a thin tube, and the refrigerant passing through the capillary tube is forced and delivered to the evaporators 81 and 82.

[0113] Each of the first evaporator 81 and the second evaporator 82 may cool the air. The refrigerant flowing inside the evaporators 81 and 82 may absorb the heat from the surrounding air by heat exchange with the surrounding air of the evaporators 81 and 82, and thus the air exchanged heat with the refrigerant may be cooled. The cooled air may be supplied to the storage compartment 20 according to the operation of the fans F1 and F2.

[0114] The first fan F1 may move the air cooled by the first evaporator 81 to the upper storage compartment 22. The second fan F2 may move the air cooled by the second evaporator 82 to the lower storage compartments 23 and 24. The processor 320 may adjust a rotational speed of each of the first fan F1 and the second fan F2. As the first fan F1 operates, heat exchange between the air and the refrigerant flowing through the first evaporator 81 may occur smoothly. As the second fan F2 operates, heat exchange between the air and the refrigerant flowing through the second evaporator 82 may occur smoothly.

[0115] The third fan F3 may be located around the condenser and may supply air toward the condenser. The operation of the third fan F3 may be synchronized with the operation of the compressor 70. For example, the processor 320 may operate the third fan F3 when the compressor 70 operates, and may stop the third fan F3 when the compressor 70 is stopped. In addition, the processor 320 may increase a rotational speed of the third fan F3 when an operating frequency and/or RPM of the compressor 70 increases. As the third fan F3 operates, heat exchange between the air and the refrigerant flowing in the condenser may occur faster.

[0116] The refrigerator 1 may include a first temperature sensor 91, a second temperature sensor 92 and a food sensor 93. The first temperature sensor 91 may correspond to a refrigerating compartment temperature sensor and the second temperature sensor 92 may correspond to a freezing compartment temperature sensor.

[0117] The first temperature sensor 91 may detect a temperature of the upper storage compartment 22. The first temperature sensor 91 may be located in the upper storage compartment 22. The first temperature sensor 91 may transmit an electrical signal corresponding to the temperature of the upper storage compartment 22 to the processor 320. The processor 320 may identify the temperature of the upper storage compartment 22 based on the electrical signal transmitted from the first temperature sensor 91.

[0118] The second temperature sensor 92 may detect temperatures of the lower storage compartments 23 and 24. The second temperature sensor 92 may be located in the lower storage compartment 23 and 24. The second temperature sensor 92 may transmit an electrical signal corresponding to the temperature of each of the lower storage compartments 23 and 24 to the processor 320. The processor 320 may identify the temperatures of the lower storage compartments 23 and 24 based on the electrical signal transmitted from the second temperature sensor 92.

[0119] The food sensor 93 may include a variety of sensors for identifying food. For example, the food sensor 93 may include a camera, an optical sensor (e.g., infrared sensor), a weight sensor and/or a temperature sensor. The food sensor 93 may obtain image data, weight data, and/or temperature data of the food.

[0120] The processor 320 may identify the food placed in the storage compartment 20 by using the image data, the weight data, and/or the temperature data obtained by the food sensor 93. The processor 320 may use various artificial intelligence (AI) algorithms (e.g., deep learning algorithms) to process the image data, the weight data, and/or the temperature data, and may identify the food from the image data, the weight data and/or the temperature data. In addition, the processor 320 may process various data obtained by the food sensor 93 to identify the type, quantity, volume and/or size of the food.

[0121] The circuit system for dielectric heating of the food may include an electro magnetic interference (EMI) filter 110, a power factor correction (PFC) circuit 120, a direct current (DC) converter 130, the RF power supply 140, an impedance matching circuit 150, and the electrode 90. In addition, the circuit system may include a voltage-current detector 160 for detecting an output voltage and an output current of the electrode 90, at least one voltage control circuit 170 for adjusting an input voltage of the RF power supply 140, and a frequency control circuit 190 for generating a switching signal to turn the RF power supply 140 on or off.

[0122] The EMI filter 110 may remove noise contained in AC power supplied from the commercial AC power supply. The EMI filter 110 may be provided as a circuit of various electronic components, such as capacitors, inductors, and diodes, connected in parallel and/or series. The EMI filter 110 may dissipate the noise contained in the AC power through the ground wire. The EMI filter 110 may be provided as a passive filter or an active filter.

[0123] The PFC circuit 120 may compensate for a power factor of AC power. The PFC circuit 120 may compensate for the power factor by reducing or eliminating reactive power among the reactive power and active power constituting the AC power. By compensating for the power factor, power loss may be reduced. The PFC circuit 120 may be provided as a circuit of various electronic components, such as capacitors, inductors, and diodes, connected in parallel and/or series. The PFC circuit 120 may be controlled by the controller 300.

[0124] The DC converter 130 may convert the power output from the PFC circuit 120 to the DC power suitable for the RF power supply 140. The DC converter 130 may deliver the converted DC power to the RF power supply 140. The DC converter 130 may apply a voltage to the RF power supply 140. The DC converter 130 may be provided as a circuit of various electronic components, such as transistors, inductors, and diodes, connected in parallel and/or series.

[0125] The RF power supply 140 may generate an RF signal, and may apply the RF signal to the electrode 90. Sinusoidal power may be applied to the electrode 90 by the RF signal. The controller 300 may control the RF power supply 140 to generate an electric field between the plurality of electrodes 90. As the RF power supply 140 operates, an electric field may be generated for dielectric heating of the food placed between the plurality of electrodes 90.

[0126] The impedance matching circuit 150 may be disposed between the RF power supply 140 and the electrode 90. The RF signal generated by the RF power supply 140 may be transmitted to the electrode 90 through the impedance matching circuit 150.

[0127] The impedance matching circuit 150 may match an output impedance of the RF power supply 140 and an electrode impedance of the electrode 90. In a case where the output impedance of the RF power supply 140 is different from the electrode impedance of the electrode 90, reflected power may be generated from the electrode 90 and a power transmission efficiency may be reduced. In order to minimize the reflected power, the matching of the output impedance of the RF power supply 140 and the electrode impedance of the electrode 90 may be performed. The controller 300 may control the impedance matching circuit 150 to perform the impedance matching.

[0128] The electrode impedance may vary depending on a state of the food placed between the plurality of electrodes 90. For example, the electrode impedance may vary due to various factors, such as a type of the food, a size of the food, an amount of water contained in the food, and a temperature of the storage compartment 20 in which the food is placed. Accordingly, the electrode impedance may correspond to an impedance of the food.

[0129] In a case where a dielectric material with a high permittivity (e.g., food having a high moisture content) is present between the first electrode 90a and the second electrode 90b, charge is accumulated in the dielectric material, and thus an intensity of the electric field formed between the first electrode 90a and the second electrode 90b may be reduced. In a case where the intensity of the electric field is reduced, a magnitude of the output voltage detected between the first electrode 90a and the second electrode 90b may be reduced, and the impedance of the food may be determined to be low.

[0130] The higher the moisture content of the food, the lower the impedance of the food. In addition, the lower the temperature of the food, the higher the impedance of the food. As the temperature of the food decreases, the kinetic energy of water molecules and the dissolved ions decreases, reducing ion mobility. As a result, charge movement may become more restricted, electrical conductivity may decrease, and impedance may increase. In other words, the impedance of the food may be inversely proportional to the temperature of the food.

[0131] The voltage-current detector 160 may detect the output voltage and output current of the electrode 90. For example, the voltage-current detector 160 may detect the output voltage between the first electrode 90a and the second electrode 90b and the output current of the first electrode 90a. The voltage-current detector 160 may detect the output voltage between the first electrode 90a and the second electrode 90b and the output current of the first electrode 90a at each predetermined time interval. The voltage-current detector 160 may transmit an electrical signal corresponding to the detected output voltage and output current of the electrode 90 to the controller 300. The processor 320 may determine the impedance of the food based on the output voltage and the output current of the electrode 90 obtained from the voltage-current detector 160.

[0132] The processor 320 may control the voltage-current detector 160 to periodically detect the output voltage between the first electrode 90a and the second electrode 90b and the output current of the first electrode 90a. The processor 320 may identify an impedance change rate of the food based on the periodically detected output voltage and output current of the electrode 90. The impedance change rate of the food may indicate the amount of change in impedance of food during a unit time.

[0133] For example, in a case where the food is placed between the first electrode 90a and the second electrode 90b in the lower storage compartments 23 and 24 and an operation mode of the lower storage compartments 23 and 24 is set to a freezing mode, the temperature of the food may be nonlinearly reduced and converged to a specific temperature (e.g., a target temperature). As the food is cooled, the impedance change rate of the food may gradually decrease. Once the food is cooled, the impedance of the food may be nonlinearly increased and converged to a specific impedance.

[0134] The at least one voltage control circuit 170 or 180 may be connected to at least one of the DC converter 130 or the PFC circuit 120. For example, the refrigerator 1 may include at least one of the first voltage control circuit 170, connected to an output end of the DC converter 130, or the second voltage control circuit 180 connected to an output end of the PFC circuit 120. The processor 320 may control the at least one voltage control circuit 170 and 180 to adjust an input voltage of the RF power supply 140. The processor 320 may adjust the input voltage of the RF power supply 140 by adjusting a reference voltage applied to the at least one voltage control circuit 170 and 180. By adjusting the input voltage of the RF power supply 140, a magnitude of the RF power supplied to the plurality of electrodes 90 may be adjusted, and the intensity of the electric field generated between the plurality of electrodes 90 may be adjusted.

[0135] The frequency control circuit 190 may generate a switching signal to turn the RF power supply 140 on or off. The processor 320 may adjust an on-off duty ratio of the frequency control circuit 190. The on-off duty ratio of the frequency control circuit 190 may indicate a ratio of an on-time to an off-time of the frequency control circuit 190. When the frequency control circuit 190 is turned on, the switching signal may be output, and when the frequency control circuit 190 is turned off, the output of the switching signal may be stopped. As the on-off duty ratio increases, the more the output duration of the switching signal may be increased. The on-off duty ratio of the frequency control circuit 190 may be described as an on-off duty ratio of the RF power supply 140.

[0136] In addition, the processor 320 may adjust a frequency of the switching signal generated by the frequency control circuit 190. The frequency of the switching signal may be referred to as a switching frequency. The higher the frequency of the switching signal, the shorter the switching signal cycle. As the frequency of the switching signal increases, a switching speed of a switching element SW_pa1 included in the RF power supply 140 may increase. As the switching speed of the switching element SW_pa1 increases, a large amount of RF power may be supplied from the RF power supply 140 to the electrode 90.

[0137] The refrigerator 1 may include a user interface 210. The user interface 210 may perform interaction between a user and the refrigerator 1. The user interface 210 may obtain a user input and may display various information about the refrigerator 1. The user interface 210 may be provided in various positions of the refrigerator 1. The user interface 210 may include at least one input interface 211 and at least one output interface 212.

[0138] For example, the input interface 211 may convert sensory information received from the user to an electrical signal. The input interface 211 may include a variety of buttons, switches and/or dials. For example, the input interface 211 may include a tact switch, push switch, slide switch, toggle switch, micro switch, touch switch, touchpad, touch screen, jog dial, and/or microphone.

[0139] The output interface 212 may visually and/or audibly transmit information related to the operation of the refrigerator 1 to the user. The information about the operation of the refrigerator 1 may be output as an image, text, indicator and/or voice. In addition, the output interface 212 may display a graphical user interface (GUI) that enables the control of the refrigerator 1. In other words, a display may display a user interface (UI) element such as an icon. The output interface 212 may include at least one of the display or speaker. The display may include a touch screen to be used as an input device.

[0140] A communication interface 220 may communicate with a user device (e.g., mobile device, smartphone) and/or a server over the network. The processor 320 may obtain various information, signals and/or data from the user device and/or the server via the communication interface 220. For example, the communication interface 220 may receive a remote control signal from the user device. The processor 320 may obtain firmware and/or software for operation of the refrigerator 1 from the server via the communication interface 220.

[0141] The communication interface 220 may include various communication circuits. The communication interface 220 may include a wireless communication circuit and/or a wired communication circuit. For example, the communication interface 220 may include a communication circuit that supports wireless communication methods, such as wireless local area network, home radio frequency (Home RF), infrared communication, ultra-wideband (UWB) communication, Wi-Fi, Bluetooth, and Zigbee.

[0142] The processor 320 may set an operation mode of the refrigerator 1 based on the user input obtained via the user interface 210 or the user device. A variety of operation modes of the refrigerator 1 may be provided. For example, the operation mode of the refrigerator 1 may include a refrigerating mode, a freezing mode, a non-freezing mode (supercooling mode) and a defrost mode.

[0143] The operation mode of the refrigerator 1 may be set for each of the plurality of storage compartments 20. The operation mode set for each of the plurality of storage compartments 20 may be the same or different. For example, the refrigerating mode may be set for the upper storage compartment 22, and the freezing mode may be set for the lower storage compartments 23 and 24.

[0144] The operation mode of the refrigerator 1 may be set for each of the plurality of accommodation spaces formed by the shelves 25, the storage containers 26 and 36, and/or the electrodes 90. The operation mode set for each of the plurality of accommodation spaces may be the same or different. For example, the refrigerating mode may be set for each of the plurality of accommodation spaces divided by the shelf 25 and the first storage container 26 within the upper storage compartment 22. The non-freezing mode (supercooling mode) may be for the accommodation space formed between the first electrode 90a and the second electrode 90b within the lower storage compartment 23 and 24, and the freezing mode may be set for another accommodation space in the lower storage compartment 23 and 24.

[0145] A target temperature of each of the plurality of storage compartments 20 and/or a target temperature of food placed in each of the plurality of accommodation spaces may be determined differently depending on the set operation mode. Because the cooled air is supplied into the storage compartment 20, a temperature of the food placed in the storage compartment 20 usually follows a temperature of the storage compartment 20. However, in a case where the food is placed between the plurality of electrodes 90, by generating an electric field between the plurality of electrodes 90 for dielectric heating of the food, the temperature of the food may be different from the temperature of the storage compartment 20. Accordingly, the temperature of the storage compartment 20 and the temperature of the food may be controlled independently.

[0146] In the refrigerating mode and the freezing mode, the target temperature of the storage compartment 20 may be set to be the same as the target temperature of the food or may be set to be lower than the target temperature of the food. For example, in the refrigerating mode, the target temperature of the food may be set to 3 C. to 4 C. In the freezing mode, the target temperature of the food may be set to 18 C. to 20 C. When dielectric heating using an electric field is performed, the temperature of the food may be maintained higher than the temperature of the storage compartment 20.

[0147] In the non-freezing mode (supercooling mode) and the defrost mode, the target temperature of the storage compartment 20 may be set to be lower than the target temperature of the food. For example, in a case where the freezing mode is set for the lower storage compartments 23 and 24 and the non-freezing mode (supercooling mode) is set for the space between the first electrode 90a and the second electrode 90b, the processor 320 may set the target temperature of the lower storage compartments 23 and 24 to be lower than the target temperature of the food placed between the first electrode 90a and the second electrode 90b.

[0148] In the non-freezing mode (supercooling mode), the target temperature of the food may be set to be lower than a freezing point of the food. In the non-freezing mode (supercooling mode), the food temperature may be lower than the freezing point, but the food may remain in a non-frozen state. In general, water molecules in food are coupled to each other at a temperature below 0 C. However, when dielectric heating using an electric field is performed, even though the temperature of the storage compartment 20 where the food is placed is maintained at a temperature low enough to freeze the food, the coupling of the water molecules in the food may be disturbed and freezing may not occur.

[0149] The defrost mode is an operation mode for defrosting (thawing) frozen food. In the defrost mode, a target temperature of the food may be set to room temperature (e.g., 20 C.). When dielectric heating using an electric field is performed, the food may be thawed without damaging the tissue of the food. Because the food may be thawed in the refrigerator 1, a user does not need to thaw the food separately after taking the food out of the refrigerator 1. Accordingly, user convenience may be improved.

[0150] The components of the refrigerator 1 that are electrically connected to the controller 300 and/or the processor 320 are not limited to the above examples. The refrigerator 1 may further include other components in addition to the components described above.

[0151] The processor 320 may set a first target temperature of the storage compartment 20 and a second target temperature of the food placed between and the plurality of electrodes 90 according to an operation mode. The processor 320 may control the compressor 70 to allow a temperature of the storage compartment 20 to be maintained at the first target temperature. The processor 320 may control the at least one voltage control circuit 170 and 180 and the frequency control circuit 190 based on the first target temperature of the storage compartment 20 and the second target temperature of the food.

[0152] For example, based on the first target temperature of the storage compartment 20 and the second target temperature of the food, the processor 320 may adjust a reference voltage applied to the at least one voltage control circuit 170 and 180, an on-off duty ratio of the frequency control circuit 190, and/or a frequency of a switching signal generated by the frequency control circuit 190. As the second target temperature of the food is set higher, the processor 320 may set the reference voltage applied to the at least one voltage control circuit 170 and 180, the on-off duty ratio of the frequency control circuit 190, and/or the frequency of the switching signal generated by the frequency control circuit 190 to be higher.

[0153] To make food be in a non-frozen state (i.e., supercooled state), an electric field applied to the food requires to be precisely adjusted. Because a temperature and an impedance of food are affected by various factors such as a type of food, a size of the food, an amount of water contained in the food, and a temperature of the storage compartment 20 where the food is placed, making the food non-frozen may not be easy unless the electric field to be applied is precisely adjusted.

[0154] The refrigerator 1 according to the disclosure may use the circuit system for dielectric heating of the food to make the food non-frozen (supercooling) and maintain the non-frozen state of the food. For example, the processor 320 of the refrigerator 1 may identify an impedance change rate of the food placed between the first electrode 90a and the second electrode 90b, based on an output voltage and an output current periodically detected by the voltage-current detector 160. The processor 320 may adjust the reference voltage applied to the at least one voltage control circuit 170 and 180, the on-off duty ratio of the frequency control circuit 190, and/or the frequency of the switching signal generated by the frequency control circuit 190, based on the impedance change rate of the food. Through the above, the refrigerator 1 may keep the food in the non-frozen (supercooled) state. Accordingly, long-term storage of food may be achieved without deterioration of food quality.

[0155] The processor 320 may apply the reference voltage to the at least one voltage control circuit 170 and 180 to generate an electric field between the first electrode 90a and the second electrode 90b, based on the impedance change rate of the food being less than or equal to a threshold value after the compressor 70 starts operating. In this instance, the processor 320 may set the on-off duty ratio of the frequency control circuit 190 to a reference duty ratio (e.g., 100%), and may set the frequency of the switching signal to a reference frequency.

[0156] The processor 320 may adjust the reference voltage applied to the at least one voltage control circuit 170 and 180, based on the impedance change rate of the food being greater than or equal to a reference value. The processor 320 may adjust the on-off duty ratio of the frequency control circuit 190, based on the impedance change rate of the food being less than the reference value. In addition, the processor 320 may further adjust the frequency of the switching signal generated by the frequency control circuit 190 based on the impedance change rate of the food being less than the reference value. Here, the reference value may be referred to as a first reference value. The first reference value may be less than the threshold value.

[0157] The processor 320 may reduce the reference voltage applied to the at least one voltage control circuit 170 and 180 to reduce an input voltage of the RF power supply 140, based on a decrease in the impedance change rate of the food. The processor 320 may reduce the on-off duty ratio of the frequency control circuit 190, based on the decrease in the impedance change rate of the food. In addition, the processor 320 may also reduce the frequency of the switching signal based on the decrease in the impedance change rate of the food.

[0158] The processor 320 may maintain the on-off duty ratio of the frequency control circuit 190 and/or the frequency of the switching signal to be constant, based on the impedance change rate of the food being within an error range of a second reference value which is less than the first reference value. The impedance change rate of food being within the error range of the second reference value may indicate that the food is in a non-frozen state. Accordingly, it is preferable to maintain the on-off duty ratio of the frequency control circuit 190 and/or the frequency of the switching signal to be constant in order to maintain the non-frozen state of food.

[0159] The processor 320 may obtain food information corresponding to food identified by the food sensor 93 and electric field control information corresponding to the food information from the memory 310 or user device. Based on the electric field control information, the processor 320 may determine the reference voltage applied to the at least one voltage control circuit 170 and 180, the on-off duty ratio of the frequency control circuit 190, and/or the frequency of the switching signal generated by the frequency control circuit 190.

[0160] The refrigerator 1 according to the disclosure may control the at least one voltage control circuit 170 and 180 for adjusting the input voltage of the RF power supply 140, and the frequency control circuit 190 for generating a switching signal for turning the RF power supply on or off, thereby directly and precisely controlling the dielectric heating energy supplied to the food.

[0161] FIG. 4 illustrates a circuit system for dielectric heating of food according to an embodiment of the disclosure.

[0162] FIGS. 5 and 6 illustrate a detailed circuit structure of the circuit system of FIG. 4 according to various embodiments of the disclosure.

[0163] Referring to FIGS. 4, 5, and 6, the EMI filter 110 may be connected to the commercial AC power supply and remove a noise of the AC power supplied from the commercial AC power supply. The EMI filter 110 may provide the AC power from which the noise is removed to the PFC circuit 120. The EMI filter 110 may be provided as a circuit of various elements connected in parallel and/or series. For example, the EMI filter 110 may include a plurality of capacitors C1 and C2 connected in parallel, a plurality of inductors L1 and L2 that implement a transformer, and a plurality of diodes D1, D2, D3, and D4 that form a bridge. The circuit structure of the EMI filter 110 is not limited to the above example. The circuit structure of the EMI filter 110 may vary depending on the design.

[0164] The PFC circuit 120 may compensate for a power factor of the AC power provided from the EMI filter 110. The PFC circuit 120 may provide the DC converter 130 with the power factor compensated power. The PFC circuit 120 may be provided as a circuit of various elements connected in parallel and/or series. For example, the PFC circuit 120 may include a plurality of electrolytic capacitors Cpf1 and Cpf2, an inductor Lpf, a diode Dpf and a switching element SW_pf. The switching element SW_pf may correspond to a transistor. The transistor may allow or block current flow in response to application of the voltage. The switching element SW_pf of the PFC circuit 120 may be referred to as a first switching element. The circuit structure of the PFC circuit 120 is not limited to the above example. The circuit structure of the PFC circuit 120 may vary depending on the design.

[0165] The DC converter 130 may convert the power output from the PFC circuit 120 to DC power. The DC converter 130 may deliver the converted DC power to the RF power supply 140. The DC converter 130 may be provided as a circuit of various elements connected in parallel and/or series. For example, the DC converter 130 may include a switching element SW_dc, an inductor Ldc and a diode Ddc. The switching element SW_dc may correspond to a transistor. The switching element SW_dc and the inductor Ldc may be connected in series. The diode Ddc may be connected to a connection node of the switching element SW_dc and the inductor Ldc. The switching element SW_dc of the DC converter 130 may be referred to as a second switching element. The circuit structure of the DC converter 130 is not limited to the above example. The circuit structure of the DC converter 130 may vary depending on the design.

[0166] The first voltage control circuit 170 may be connected to an output end of the DC converter 130, and an input voltage of the RF power supply 140 may be adjusted under the control of the controller 300. The first voltage control circuit 170 may be provided as a circuit of various elements connected in parallel and/or series. For example, the first voltage control circuit 170 may include resistors R1, R2, and R3, a capacitor Cdc, and an operational amplifier (OP-AMP) OP1.

[0167] One end of the first resistor R1 may be connected to one end of the inductor Ldc included in the DC converter 130, and the other end of the first resistor R1 may be connected to the second resistor R2. A connection node of the first resistor R1 and the second resistor R2 may be connected to a minus () input terminal of the operational amplifier OP1. A plus (+) input terminal of the operational amplifier OP1 may be connected to the controller 300. An output terminal of the operational amplifier OP1 may be connected to one end of the third resistor R3 and the capacitor Cdc connected in parallel. The third resistor R3 and the capacitor Cdc connected in parallel may correspond to a compensation circuit to ensure stability of the circuit. The other end of the third resistor R3 and the capacitor Cdc connected in parallel may be connected to the switching element SW_dc of the DC converter 130. The circuit structure of the first voltage control circuit 170 is not limited to the above example.

[0168] The controller 300 may adjust an input voltage VPA of the RF power supply 140 by controlling the first voltage control circuit 170. The input voltage VPA of the RF power supply 140 may be referred to as an output voltage of the DC converter 130. The processor 320 may adjust the input voltage VPA of the RF power supply 140 by adjusting a reference voltage applied to the first voltage control circuit 170. The switching element SW_dc of the DC converter 130 may be controlled by a voltage signal output from the first voltage control circuit 170. The reference voltage applied to the first voltage control circuit 170 may be referred to as a first reference voltage.

[0169] In a case where a reference voltage applied to the plus (+) input terminal of the operational amplifier OP1 is changed, a voltage applied to the minus () input terminal of the operational amplifier OP1 may be changed. When the voltage applied to the minus () input terminal of the operational amplifier OP1 is changed and the switching element SW_dc of the DC converter 130 is controlled, the input voltage VPA of the RF power supply 140 may be changed according to the voltage distribution of the first resistor R1 and the second resistor R2. The refrigerator 1 according to the disclosure may adjust an intensity of an electric field (E field) generated between the plurality of electrodes 90 by adjusting the input voltage VPA of the RF power supply 140. As the reference voltage applied to the first voltage control circuit 170 increases, the input voltage VPA of the RF power supply 140 may increase, and the intensity of the electric field may increase.

[0170] The RF power supply 140 may be provided as a circuit of various elements for generating an RF signal. For example, the RF power supply 140 may include an electrolytic capacitor Cpa11, a capacitor Cpa12, a plurality of inductors Lpa11 and Lpa12, and a switching element SW_pa1. The electrolytic capacitor Cpa11 may connect a VPA node and the ground GND. The switching element SW_pa1 and the inductor Lpa11 may be connected in series between the VPA node and the ground GND. In addition, the inductor Lpa12 and the capacitor Cpa12 connected in series may be disposed between the impedance matching circuit 150 and an N1 node connecting the switching element SW_pa1 and the inductor Lpa11. The switching element SW_pa1 of the RF power supply 140 may be referred to as a third switching element.

[0171] The switching element SW_pa1 of the RF power supply 140 may correspond to a transistor. According to the operation of the switching element SW_pa1, the RF power supply 140 may be activated (ON) or deactivated (OFF). The operation of the RF power supply 140 may be controlled according to a switching signal VG applied to the switching element SW_pa1. When the switching element SW_pa1 is turned on, the operation of the RF power supply 140 may be activated. When the switching element SW_pa1 is turned off, the operation of the RF power supply 140 may be deactivated.

[0172] The frequency control circuit 190 may generate a switching signal VG to turn the RF power supply 140 on or off. The frequency control circuit 190 may be electrically connected to the controller 300, and may output the switching signal VG for controlling the operation of the RF power supply 140 under the control of the controller 300. The switching signal VG may be output as a sinusoidal signal. The frequency control circuit 190 may include a voltage controlled oscillator (VCO).

[0173] The controller 300 may input an activation signal EN for turning on the frequency control circuit 190 into the frequency control circuit 190. The frequency control circuit 190 may be turned on or off based on whether the activation signal EN is input. When the activation signal EN is input to the frequency control circuit 190, the frequency control circuit 190 may be turned on and the switching signal may be output. The switching signal may be input to the switching element SW_pa1 of the RF power supply 140. The switching element SW_pa1 of the RF power supply 140 may be repeatedly turned on and off according to the switching signal. When the activation signal EN is not input to the frequency control circuit 190, the frequency control circuit 190 is turned off and the switching signal is not generated.

[0174] The controller 300 may input the activation signal EN to the frequency control circuit 190 as a high level 1 or a low level 0. In a case where the activation signal EN is 1, the frequency control circuit 190 may be turned on. In a case where the activation signal is 0, the frequency control circuit 190 may be turned off.

[0175] The controller 300 may periodically input the activation signal EN. The controller 300 may adjust an on-off duty ratio of the frequency control circuit 190 by adjusting a duration for which the activation signal EN is maintained at a high level for a single cycle. The on-off duty ratio of the frequency control circuit 190 may be defined as a ratio of an on-time of the frequency control circuit 190 for a single cycle. As the on-off duty ratio of the frequency control circuit 190 increases, the dielectric heating energy supplied to the food may increase.

[0176] In addition, the controller 300 may adjust a frequency of the switching signal generated by the frequency control circuit 190. The frequency of the switching signal may be referred to as a switching frequency. The controller 300 may input a frequency selection signal FS into the frequency control circuit 190 to adjust the frequency of the switching signal. The frequency of the switching signal may be determined based on the frequency selection signal FS. As the frequency of the switching signal increases, a cycle of the switching signal may become shorter and a switching speed of the switching element SW_pa1 may increase. The increase in switching speed of switching element SW_pa1 may lead to an increase in dielectric heating energy supplied to the food. On the contrary, as the frequency of the switching signal decreases, the cycle of the switching signal may become longer and the switching speed of the switching element SW_pa1 may decrease. The decrease in switching speed of switching element SW_pa1 may reduce the dielectric heating energy supplied to the food.

[0177] The impedance matching circuit 150 may be provided as a circuit in which a plurality of inductors L, a plurality of capacitors C, and a plurality of switches S1, S2, S3, S4, S5, S6, S7, S8, and S9 are connected in parallel and/or series. The plurality of switches S1, S2, S3, S4, S5, S6, S7, S8, and S9 included in the impedance matching circuit 150 may be opened or closed under the control of the controller 300. As the plurality of switches S1, S2, S3, S4, S5, S6, S7, S8, and S9 are controlled, impedance matching may be performed. It is illustrated that the impedance matching circuit 150 includes three inductors L connected in parallel, three capacitors C connected in parallel, and nine switches, but is not limited thereto. The structure of the impedance matching circuit 150 may vary depending on the design. The controller 300 may perform impedance matching according to an impedance change of the food by controlling the on/off of each of the plurality of switches S1, S2, S3, S4, S5, S6, S7, S8, and S9.

[0178] FIG. 7 illustrates a circuit system for dielectric heating of food according to an embodiment of the disclosure.

[0179] FIG. 8 illustrate a detailed circuit structure of the circuit system of FIG. 7 according to an embodiment of the disclosure.

[0180] Referring to FIGS. 7 and 8, the refrigerator 1 may include the second voltage control circuit 180 connected to an output end of the PFC circuit 120. Comparing FIGS. 4 and 7, locations of the voltage control circuits are different. In FIG. 4, the first voltage control circuit 170 is connected to the output end of the DC converter 130, and in FIG. 7, the second voltage control circuit 180 is connected to the output end of the PFC circuit 120.

[0181] The EMI filter 110, the PFC circuit 120, the DC converter 130, the RF power supply 140, the impedance matching circuit 150, the voltage-current detector 160, and the frequency control circuit 190 described in FIGS. 7 and 8 are the same as those described in FIGS. 4, 5, and 6.

[0182] The circuit structure of the second voltage control circuit 180 may be the same as that of the first voltage control circuit 170. The second voltage control circuit 180 may be provided as a circuit of various elements connected in parallel and/or series. For example, the second voltage control circuit 180 may include resistors R1, R2, and R3, a capacitor Cdc and an operational amplifier (OP-AMP) OP1.

[0183] Referring to FIG. 8, one end of the first resistor R1 may be connected to one end of a diode Dpf included in the PFC circuit 120, and the other end of the first resistor R1 may be connected to the second resistor R2. A connection node of the first resistor R1 and the second resistor R2 may be connected to a minus () input terminal of the operational amplifier OP1. A plus (+) input terminal of the operational amplifier OP1 may be connected to the controller 300. An output terminal of the operational amplifier OP1 may be connected to one end of the third resistor R3 and the capacitor Cdc connected in parallel. The third resistor R3 and the capacitor Cdc connected in parallel may correspond to a compensation circuit to ensure stability of the circuit. The other end of the third resistor R3 and the capacitor Cdc connected in parallel may be connected to a switching element SW_pf of the PFC circuit 120. The circuit structure of the second voltage control circuit 180 is not limited to the above example.

[0184] The second voltage control circuit 180 may be connected to the output end of the PFC circuit 120 and may adjust an input voltage of the DC converter 130. When the input voltage of the DC converter 130 is changed, an output voltage of the DC converter 130 is changed, and thus an input voltage VPA of the RF power supply 140 may be changed. In other words, the controller 300 may adjust the input voltage VPA of the RF power supply 140 by controlling the second voltage control circuit 180. The controller 300 may adjust the input voltage VPA of the RF power supply 140 by adjusting a reference voltage applied to the second voltage control circuit 180.

[0185] The switching element SW_pf of the PFC circuit 120 may be controlled by a voltage signal output from the second voltage control circuit 180. The reference voltage applied to the second voltage control circuit 180 may be referred to as a second reference voltage.

[0186] In a case where a reference voltage applied to the plus (+) input terminal of the operational amplifier OP1 is changed, a voltage applied to the minus () input terminal of the operational amplifier OP1 may be changed. When the voltage applied to the minus () input terminal of the operational amplifier OP1 is changed and the switching element SW_pf of the PFC circuit 120 is controlled, the input voltage of the DC converter 130 may be changed according to the voltage distribution of the first resistor R1 and the second resistor R2. The refrigerator 1 according to the disclosure may adjust an intensity of an electric field generated between the plurality of electrodes 90 by adjusting the input voltage of the DC converter 130. As the reference voltage applied to the second voltage control circuit 180 increases, the input voltage of the DC converter 130 may increase. As the input voltage of the DC converter 130 increases, the input voltage VPA of the RF power supply 140 may increase and the intensity of the electric field may increase.

[0187] FIG. 9 illustrates a circuit system for dielectric heating of food according to an embodiment of the disclosure.

[0188] Referring to FIG. 9, the refrigerator 1 may include the first voltage control circuit 170 connected to an output end of the DC converter 130, and the second voltage control circuit 180 connected to an output end of the PFC circuit 120. The circuit structure of the first voltage control circuit 170 is the same as that described in FIGS. 4 and 5. The circuit structure of the second voltage control circuit 180 is the same as that described in FIGS. 7 and 8.

[0189] The EMI filter 110, the PFC circuit 120, the DC converter 130, the RF power supply 140, the impedance matching circuit 150, the voltage-current detector 160, and the frequency control circuit 190 described in FIG. 9 are the same as those described in FIGS. 4, 5, and 6.

[0190] As described above, the processor 320 of the refrigerator 1 may adjust an output voltage of the DC converter 130 by controlling the first voltage control circuit 170. In addition, the processor 320 may adjust an input voltage of the DC converter 130 by controlling the second voltage control circuit 180. In a case where the refrigerator 1 includes both the first voltage control circuit 170 and the second voltage control circuit 180, a wider range of input voltage VPA of the RF power supply 140 may be controlled. In other words, by using both the first voltage control circuit 170 and the second voltage control circuit 180, a wider range of input voltage VPA applied to the RF power supply 140 may be controlled.

[0191] FIG. 10 illustrates an example of a switching signal output by a frequency control circuit according to an embodiment of the disclosure.

[0192] Referring to a graph 900 of FIG. 10, the processor 320 of the refrigerator 1 may input an activation signal EN for turning on the frequency control circuit 190 into the frequency control circuit 190. The frequency control circuit 190 may be turned on or off based on whether the activation signal EN is input.

[0193] When the activation signal EN is input to the frequency control circuit 190, the frequency control circuit 190 may be turned on and a switching signal VG may be output. The switching signal VG may be input to the RF power supply 140. The RF power supply 140 be repeatedly turned on and off according to the switching signal VG. When the activation signal EN is not input to the frequency control circuit 190, the frequency control circuit 190 is turned off and the switching signal VG is not output. In a case where the switching signal VG is not output from the frequency control circuit 190, the RF power supply 140 may be turned off.

[0194] The processor 320 may input the activation signal EN to the frequency control circuit 190 as a high level 1 or a low level 0. In a case where the activation signal EN is 1, the frequency control circuit 190 may be turned on. In a case where the activation signal is 0, the frequency control circuit 190 may be turned off.

[0195] The processor 320 may periodically input the activation signal EN. The processor 320 may adjust an on-off duty ratio of the frequency control circuit 190 by adjusting a duration for which the activation signal EN is maintained at a high level for a single cycle. The on-off duty ratio of the frequency control circuit 190 may be defined as a ratio of an on-time of the frequency control circuit 190 for a single cycle. As the on-off duty ratio of the frequency control circuit 190 increases, the dielectric heating energy supplied to the food may increase. In order to reduce switching losses, the on-off cycle of the frequency control circuit 190 may be determined as an integer multiple of a cycle of the switching signal VG generated by the frequency control circuit 190.

[0196] FIG. 11 is an example of a graph showing a change in food temperature and a change in food impedance in a non-freezing mode according to an embodiment of the disclosure.

[0197] While food is cooled, a rate at which the food is cooled (cooling rate) may not be constant. In other words, while the food is cooled, a temperature of the food may not change at a constant rate. For example, after the food at room temperature is placed in the refrigerator 1, the temperature of the food may decrease nonlinearly over time. The temperature of the food may be inversely proportional to an impedance of the food. As the temperature of the food decreases, the kinetic energy of water molecules and the dissolved ions decreases, reducing ion mobility. As a result, charge movement may become more restricted, electrical conductivity may decrease, and impedance may increase. A temperature change rate and an impedance change rate of the food may not be constant until the temperature and the impedance of the food reach a steady state.

[0198] Because a temperature and an impedance of the food are affected by various factors such as a type of the food, a size of the food, an amount of water contained in the food, and a temperature of the storage compartment 20 where the food is placed, making the food non-frozen may not be easy unless the electric field to be applied is precisely adjusted. Even in a case where the food enters a non-frozen state, the non-frozen state may be broken by various factors described above. Once the non-frozen state is broken, the food may be frozen and cannot return to the non-frozen state. Accordingly, in order to stably maintain the food in the non-frozen state, an electric field applied to the food requires to be precisely adjusted. The refrigerator 1 may adjust RF power supplied to the electrode 90 to adjust the electric field applied to the food.

[0199] It is described in FIG. 11 that the food is placed between the first electrode 90a and the second electrode 90b and an operation mode of an accommodation space where the food is placed and/or an operation mode of the storage compartment 20 is a non-freezing mode. Referring to a graph 1000 of FIG. 11, in a case where the food successfully enters a non-frozen state, a temperature Ft and an impedance It of the food may appear as a solid line. In a case where the food fails to enter the non-frozen state, the temperature and the impedance of the food may appear as a dotted line. The impedance graph may represent an absolute value of the impedance.

[0200] Referring to the graph 1000 of FIG. 11, cooling of the food may begin at a time t0. The refrigerator 1 may operate the compressor 70 to cool the food. The temperature of the food may decrease rapidly and non-linearly from the time to and may reach a threshold temperature T_th higher than a reference temperature T_ref at a time t1. The reference temperature T_ref may correspond to a freezing point of the food. The impedance of the food may increase from the time to and may reach a threshold impedance I_th at the time t1.

[0201] In a case where the cooling of the food starts and dielectric heating energy is supplied to the food at the same time, the cooling of the food may be delayed or the food may not be cooled. Accordingly, the refrigerator 1 may not apply an RF signal to the plurality of electrodes 90 from t0 to t1.

[0202] The impedance change rate of the food may be described by a slope of the impedance graph. At the time t1, the impedance change rate of the food may correspond to a threshold value di_th. Based on the impedance change rate of the food being less than or equal to the threshold value di_th, the refrigerator 1 may apply a reference voltage to the at least one voltage control circuit 170 and 180 to generate an electric field between the plurality of electrodes 90. When the electric field is applied to the food, dielectric heating energy may be supplied to the food, and thus the food may be heated. Accordingly, the cooling rate of the food may be slowed down. By reducing the cooling rate of the food, making the food non-frozen (supercooling) may be easier.

[0203] At a time t2, the temperature of the food may reach the reference temperature T_ref, and the impedance of the food may reach the reference impedance I_ref. The reference temperature T_ref may correspond to the freezing point of the food. At the time t2, the impedance change rate of the food may correspond to a reference value di_ref.

[0204] The refrigerator 1 may adjust the reference voltage applied to the at least one voltage control circuit 170 and 180 based on the impedance change rate of the food, until the time t2 when the impedance change rate of the food reaches the reference value di_ref. In other words, in a case where the impedance change rate of the food is greater than or equal to the reference value di_ref, the refrigerator 1 may adjust the reference voltage applied to the at least one voltage control circuit 170 and 180. The refrigerator 1 may reduce the reference voltage applied to the at least one voltage control circuit 170 and 180 to reduce an input voltage of the RF power supply 140, based on the decrease in the impedance change rate of the food. The reference value di_ref for the impedance change rate of the food may be set lower than the threshold value di_th.

[0205] Because RF power is controlled in a wider range for a period in which the temperature change and the impedance change of the food are relatively large (e.g., from t1 to t2), adjusting the input voltage of the RF power supply 140 is effective for controlling the temperature and the impedance of the food. The refrigerator 1 may adjust the input voltage of the RF power supply 140 by adjusting the reference voltage applied to the at least one voltage control circuit 170 and 180 from t1 to t2. The period from t1 to t2 may be referred to as a first control section.

[0206] The refrigerator 1 may set an on-off duty ratio of the frequency control circuit 190 from t1 to t2 as a reference duty ratio (e.g., 100%), and may set a frequency of a switching signal as a reference frequency. In a case where the on-off duty ratio of the frequency control circuit 190 is set as the reference duty ratio, the frequency control circuit 190 may be maintained in an on state and continuously output the switching signal.

[0207] From the time t2 when the temperature of the food reaches the reference temperature T_ref, the change in water content and permittivity of the food may decrease. From the time t2, the temperature change rate and the impedance change rate of the food may be significantly reduced. In a period in which the temperature change and the impedance change of the food are relatively small (e.g., from t2 to t3), the dielectric heating energy supplied to the food requires to be precisely adjusted rather than adjusting the RF power applied to the food. The refrigerator 1 may adjust the on-off duty ratio of the frequency control circuit 190 to precisely adjust the dielectric heating energy. The refrigerator 1 may maintain the reference voltage applied to the at least one voltage control circuit 170 and 180 to be constant from the time t2. The period from t2 to t3 may be referred to as a second control section.

[0208] The refrigerator 1 may adjust the on-off duty ratio of the frequency control circuit 190 in a case where the impedance change rate of the food is less than the reference value di_ref. The refrigerator 1 may reduce the on-off duty ratio of the frequency control circuit 190 based on the decrease in the impedance change rate of the food. As the on-off duty ratio of the frequency control circuit 190 is reduced, an on-time of the RF power supply 140 may decrease and an off-time may increase. The reference value di_ref at the time t2 for the impedance change rate of the food may be referred to as a first reference value.

[0209] The impedance change rate of the food gradually decreases and may reach a second reference value (e.g., 0) at a time t3. The second reference value for the impedance change rate of the food may be set lower than the first reference value di_ref. In a case where the impedance change rate of the food is within an error range of the second reference value (e.g., 0), the refrigerator 1 may determine that the food has entered a non-frozen state. The refrigerator 1 may maintain the on-off duty ratio of the frequency control circuit 190 and/or a frequency of switching signal to be constant, based on the impedance change rate of the food being within the error range of the second reference value (e.g., 0).

[0210] As such, by operating the compressor 70 to cool the food while supplying proper dielectric heating energy to the food, the food may be stored in the non-frozen (supercooled) state where the temperature of the food is lower than the freezing point but the food is not frozen. In addition, by using thermal equilibrium of the cold air supplied to the storage compartment 20 and the dielectric heating energy, the food may be stored in the non-frozen (supercooled) state with the temperature of the storage compartment 20 lowered. The refrigerator 1 may keep the food in the non-frozen (supercooled) state and inhibit spoilage of the food, thereby maintaining the good quality of the food.

[0211] Meanwhile, the refrigerator 1 may obtain food information corresponding to the food, identified by the food sensor 93, and electric field control information corresponding to the food information from the memory 310 or a user device. The refrigerator 1 may adjust the reference voltage applied to the at least one voltage control circuit 170 and 180 in the first control section based on the electric field control information. The refrigerator 1 may adjust the on-off duty ratio of the frequency control circuit 190 in the second control section based on the electric field control information.

[0212] In a case where the food is not supplied with dielectric heating energy, the food continues to cool, and thus the temperature of the food may decrease to a limit temperature T_lim. A state of the food changes from the time (e.g., t3) when the temperature of the food reaches the limit temperature T_lim, and the food may be frozen. The temperature of the food may remain at the freezing point T_ref while the state of the food changes. The impedance of the food may also increase significantly and remain constant as the food undergoes the state change.

[0213] FIG. 12 is another example of a graph showing a change in food temperature in a non-freezing mode according to an embodiment of the disclosure.

[0214] A graph 1100 of FIG. 12 shows a temperature Ft of food and a temperature St of the storage compartment 20. Referring to the graph 1100 of FIG. 12, the refrigerator 1 may set a target temperature T_set of the storage compartment 20 according to an operation mode of the storage compartment 20. For example, the operation mode of the storage compartment 20 may be a non-freezing mode, and the target temperature T_set of the storage compartment 20 may be 18 C.

[0215] The refrigerator 1 may also adjust the dielectric heating energy supplied to the food in a stepwise manner in order to make the food non-frozen. For example, in a case where electric field control information is not obtained, the refrigerator 1 may adjust an on-off duty ratio of the frequency control circuit 190 in a stepwise manner based on the temperature of the food.

[0216] The refrigerator 1 may operate the compressor 70 to cool the food. The refrigerator 1 may control the compressor 70 to maintain the temperature of the storage compartment 20 at the target temperature T_set. In addition, the refrigerator 1 may apply a reference voltage to the at least one voltage control circuit 170 and 180 to generate an electric field between the plurality of electrodes 90 based on the temperature of the food.

[0217] The refrigerator 1 may reduce the on-off duty ratio of the frequency control circuit 190 in a stepwise manner from a time ta when the temperature of the food reaches a freezing point T_fp. For example, the refrigerator 1 may determine the on-off duty ratio of the frequency control circuit 190 from the time ta to a time tb as a first duty ratio. The refrigerator 1 may change the on-off duty ratio of the frequency control circuit 190 to a second duty ratio at the time tb, and may change the on-off duty ratio of the frequency control circuit 190 to a third duty ratio at a time tc. The first duty ratio may be the largest, and the third duty ratio may be the smallest. The second duty ratio may be greater than the third duty ratio and less than the first duty ratio. As the on-off duty ratio of the frequency control circuit 190 decreases in a stepwise manner, the dielectric heating energy supplied to the food may also be reduced in a stepwise manner.

[0218] When the food enters the non-frozen state, the refrigerator 1 may maintain the on-off duty ratio of the frequency control circuit 190 at a fourth duty ratio less than the third duty ratio. As a result, the food may be maintained in the non-frozen state. The temperature of the food may be maintained higher than the limit temperature T_lim.

[0219] FIG. 13 is an example of a graph showing a change in food temperature in a refrigerating mode according to an embodiment of the disclosure.

[0220] Referring to a graph 1200 of FIG. 13, an operation mode of an accommodation space where food is placed may be set to a refrigerating mode, and an operation mode of the storage compartment 20 may be set to a freezing mode. The refrigerator 1 may operate the compressor 70 to maintain a temperature St of the storage compartment 20 at a first target temperature T_set1. The refrigerator 1 may control an operation of the RF power supply 140 to allow a temperature of the food to converge to a second target temperature T_set2. For example, the first target temperature T_set1 may be 18 C., and the second target temperature T_set2 may be 3 C.

[0221] As such, the refrigerator 1 may keep the food refrigerated even in a freezing environment that may freeze the food by supplying proper dielectric heating energy to the food.

[0222] FIG. 14 is an example of a graph showing a change in food temperature in a defrost mode according to an embodiment of the disclosure.

[0223] Referring to a graph 1300 of FIG. 14, an operation mode of an accommodation space where food is placed may be set to a defrost mode. An operation mode of the storage compartment 20 may be set to a freezing mode. The refrigerator 1 may operate the compressor 70 to maintain a temperature St of the storage compartment 20 at a first target temperature T_set1. The refrigerator 1 may control an operation of the RF power supply 140 to allow a temperature Ft of the food to converge to a second target temperature T_set2. For example, the first target temperature T_set1 may be 18 C., and the second target temperature T_set2 may be 20 C. The temperature Ft of the food in a frozen state may be lower than a freezing point T_ft. By applying an electric field to the food, the food may be heated and the temperature Ft of the food may increase. As the food is heated, a state change of the food may occur (e.g., solid state.fwdarw.liquid state).

[0224] As such, the refrigerator 1 may thaw the food even in a freezing environment that may freeze the food by supplying proper dielectric heating energy to the food.

[0225] FIG. 15 is a flowchart illustrating a method performed by a refrigerator according to an embodiment of the disclosure.

[0226] Referring to FIG. 15, the processor 320 of the refrigerator 1 may operate the compressor 70 to supply a refrigerant to the evaporators 81 and 82 in order to cool the storage compartment 20 at operation 1401. For example, the processor 320 may set a first target temperature of the storage compartment 20 according to an operation mode. The processor 320 may control the compressor 70 to allow a temperature of the storage compartment 20 to be maintained at the first target temperature.

[0227] A plurality of electrodes 90 may be arranged in the storage compartment 20. The plurality of electrodes 90 may be spaced apart from each other to be parallel to each other. For example, the first electrode 90a and the second electrode 90b may be spaced apart and be parallel in the storage compartment 20. The first electrode 90a and the second electrode 90b may each be included in the shelf. The first electrode 90a and the second electrode 90b may be fixed to or detachable from the inner case 11.

[0228] Food may be placed between the first electrode 90a and the second electrode 90b. For example, the first electrode 90a and the second electrode 90b may divide the storage compartment 20 into a plurality of accommodation spaces. Food may be placed in a space between the first electrode 90a and the second electrode 90b. The storage containers 26 and 36 containing the food may each be placed between the first electrode 90a and the second electrode 90b.

[0229] The processor 320 may detect an output voltage between the first electrode 90a and the second electrode 90b and detect an output current of the first electrode 90a through the voltage-current detector 160 at operation 1402. The processor 320 may control the voltage-current detector 160 to periodically detect the output voltage between the first electrode 90a and the second electrode 90b and the output current of the first electrode 90a. The voltage-current detector 160 may detect the output voltage between the first electrode 90a and the second electrode 90b and the output current of the first electrode 90a at time intervals set by the processor 320.

[0230] The processor 320 may determine an impedance change rate of the food based on the periodically detected output voltage and output current of the electrode 90 at operation 1403. The impedance change rate of the food may indicate the amount of change in impedance of food during a unit time. The impedance change rate of the food may be described by a slope of impedance graph. The impedance of the food may vary due to various factors, such as a type of the food, a size of the food, an amount of water contained in the food, and a temperature of the storage compartment 20 in which the food is placed. For example, the higher the moisture content of the food, the lower the impedance of the food. In addition, the lower the temperature of the food, the higher the impedance of the food. The impedance of the food may be inversely proportional to the temperature of the food. As the food is cooled, the impedance change rate of the food may gradually decrease. Once the food is cooled, the impedance of the food may be nonlinearly increased and converged to a specific impedance.

[0231] The processor 320 may adjust a reference voltage applied to the at least one voltage control circuit 170 and 180 or an on-off duty ratio of the frequency control circuit 190 based on the impedance change rate of the food at operation 1404. In addition, the processor 320 may adjust a frequency of a switching signal generated by the frequency control circuit 190 based on the impedance change rate of the food. Through the above, the refrigerator 1 may keep the food in a non-frozen (supercooled) state. Accordingly, long-term storage of food may be achieved without deterioration of food quality.

[0232] FIG. 16 is a flowchart illustrating the method performed by a refrigerator of FIG. 15 in more detail according to an embodiment of the disclosure.

[0233] Referring to FIG. 16, the processor 320 of the refrigerator 1 may operate the compressor 70 to supply the refrigerant to the evaporators 81 and 82 in order to cool the storage compartment 20 at operation 1501. The processor 320 may detect the output voltage between the first electrode 90a and the second electrode 90b and the output current of the first electrode 90a through the voltage-current detector 160 at operation 1502. The processor 320 may determine the impedance change rate of the food based on the periodically detected output voltage and output current of the electrode 90 at operation 1503. The operation 1501, operation 1502 and operation 1503 correspond to the operation 1401, operation 1402 and operation 1403 described in FIG. 15.

[0234] The processor 320 may apply the reference voltage to the at least one voltage control circuit 170 and 180 to generate an electric field between the first electrode 90a and the second electrode 90b, based on the impedance change rate of the food being less than or equal to a threshold value after the cooling of the food starts at operation 1504. In this instance, the processor 320 may set the on-off duty ratio of the frequency control circuit 190 as a reference duty ratio (e.g., 100%), and may set the frequency of the switching signal as a reference frequency. In a case where the on-off duty ratio of the frequency control circuit 190 is set as the reference duty ratio, the frequency control circuit 190 may be maintained in an on state and continuously output the switching signal.

[0235] In a case where the impedance change rate of the food is greater than the threshold value, the refrigerator 1 may not apply an RF signal to the first electrode 90a and the second electrode 90b to prevent a delay and/or failure in cooling the food.

[0236] When the electric field is applied to the food, dielectric heating energy may be supplied to the food, and thus the food may be heated. Accordingly, the cooling rate of the food may be slowed down. By reducing the cooling rate of the food, making the food non-frozen may be easier.

[0237] The processor 320 may identify whether the impedance change rate of the food is greater than or equal to a first reference value at operation 1505. The processor 320 may adjust the reference voltage applied to the at least one voltage control circuit 170 and 180, based on the impedance change rate of the food being greater than or equal to the first reference value at operation 1506. The first reference value may be lower than the threshold value described in operation 1504.

[0238] For example, the processor 320 may reduce the reference voltage applied to the at least one voltage control circuit 170 and 180 to reduce an input voltage of the RF power supply 140, based on the decrease in the impedance change rate of the food. In a case where the input voltage of the RF power supply 140 decreases, an intensity of the electric field generated between the first electrode 90a and the second electrode 90b may be reduced. Because RF power is controlled in a wider range for a period in which the temperature change and the impedance change of the food are relatively large, adjusting the input voltage of the RF power supply 140 is effective for controlling the temperature and the impedance of the food.

[0239] The processor 320 may adjust the on-off duty ratio of the frequency control circuit 190, based on the impedance change rate of the food being less than the first reference value at operation 1507. In addition, the processor 320 may further adjust the frequency of the switching signal generated by the frequency control circuit 190, based on the impedance change rate of the food being less than the first reference value. The refrigerator 1 may maintain the reference voltage applied to the at least one voltage control circuit 170 and 180 to be constant while adjusting the on-off duty ratio of the frequency control circuit 190.

[0240] For example, the processor 320 may reduce the on-off duty ratio of the frequency control circuit 190 based on the decrease in the impedance change rate of the food. In addition, the processor 320 may reduce the frequency of the switching signal based on the decrease in the impedance change rate of the food.

[0241] As the food is cooled, a water content and permittivity of the food may decrease. As the food is cooled, a temperature change rate and an impedance change rate of the food may decrease. In a period in which the temperature change and the impedance change of the food are relatively small, the dielectric heating energy supplied to the food requires to be precisely adjusted rather than adjusting the RF power applied to the food. The refrigerator 1 may adjust the on-off duty ratio of the frequency control circuit 190, thereby precisely adjusting the dielectric heating energy.

[0242] The processor 320 may identify whether the impedance change rate of the food is within an error range of a second reference value lower than the first reference value at operation 1508. The processor 320 may maintain the on-off duty ratio of the frequency control circuit 190 to be constant, based on the impedance change rate of the food being within the error range of the second reference value lower than the first reference value at operation 1509. In addition, based on the impedance change rate of the food being within the error range of the second reference value, the processor 320 may maintain the frequency of the switching signal, generated by the frequency control circuit 190, to be constant. The second reference value for the impedance change rate of the food may correspond to 0.

[0243] The impedance change rate of the food being within the error range of the second reference value may indicate that the food is in a non-frozen state. Accordingly, it is preferable to maintain the on-off duty ratio of the frequency control circuit 190 and/or the frequency of the switching signal to be constant, in order to maintain the non-frozen state of the food.

[0244] As such, by operating the compressor 70 to cool the food while supplying proper dielectric heating energy to the food, the food may be stored in the non-frozen (supercooled) state where the temperature of the food is lower than the freezing point but the food is not frozen. The refrigerator 1 may keep the food in the non-frozen (supercooled) state and inhibit spoilage of the food, thereby maintaining the good quality of the food.

[0245] FIG. 17 is a flowchart illustrating addible operations to the method performed the refrigerator described in FIG. 15 according to an embodiment of the disclosure.

[0246] Referring to FIG. 17, the processor 320 of the refrigerator 1 may obtain food information corresponding to food, identified by the food sensor 93, from the memory 310 or a user device at operation 1601. For example, the food information may include various information, such as a type of the food, a size of the food, a volume of the food and/or number of foods.

[0247] The processor 320 may obtain electric field control information corresponding to the food information from the memory 310 or the user device at operation 1602. For example, the electric field control information may include the on-off duty ratio of the RF power supply 140 and a magnitude of the input voltage of the RF power supply 140 corresponding to an impedance value and/or impedance change rate of the food.

[0248] The processor 320 may adjust the reference voltage applied to the at least one voltage control circuit 170 and 180 or the on-off duty ratio of the frequency control circuit 190 based on the electric field control information at operation 1603. In addition, the processor 320 may adjust the frequency of the switching signal generated by the frequency control circuit 190 based on the electric field control information.

[0249] According to an embodiment of the disclosure, a refrigerator may include: a storage compartment; an evaporator configured to cool the storage compartment; a compressor configured to supply a refrigerant to the evaporator; a first electrode arranged in the storage compartment; a second electrode arranged spaced apart from the first electrode in the storage compartment; a radio frequency (RF) power supply configured to apply an RF signal to the first electrode and the second electrode; at least one voltage control circuit configured to adjust an input voltage of the RF power supply; a frequency control circuit configured to generate a switching signal for turning the RF power supply on or off; a voltage-current detector configured to detect an output voltage between the first electrode and the second electrode and an output current of the first electrode; memory storing instructions; and at least one processor operatively couple to the compressor, the at least one voltage control circuit, the frequency control circuit, the voltage-current detector, and the memory. The instructions, when executed by the at least one processor individually or collectively, may cause the refrigerator to: operate the compressor to cool the storage compartment, identify an impedance change rate of food placed between the first electrode and the second electrode based on the output voltage and the output current periodically detected by the voltage-current detector, and adjust a reference voltage applied to the at least one voltage control circuit or an on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food.

[0250] The instructions, when executed by the at least one processor individually or collectively, may further cause the refrigerator to adjust the reference voltage applied to the at least one voltage control circuit, based on the impedance change rate of the food being greater than or equal to a reference value, and adjust the on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food being less than the reference value.

[0251] The instructions, when executed by the at least one processor individually or collectively, may further cause the refrigerator to reduce the reference voltage to reduce the input voltage, and reduce the on-off duty ratio of the frequency control circuit, based on a decrease in the impedance change rate of the food.

[0252] The instructions, when executed by the at least one processor individually or collectively, may further cause the refrigerator to adjust a frequency of the switching signal, based on the impedance change rate of the food being less than the reference value.

[0253] The instructions, when executed by the at least one processor individually or collectively, may further cause the refrigerator to reduce the frequency of the switching signal, based on a decrease in the impedance change rate of the food.

[0254] The reference value may be a first reference value, and the instructions, when executed by the at least one processor individually or collectively, may further cause the refrigerator to maintain the on-off duty ratio of the frequency control circuit to be constant, based on the impedance change rate of the food being within an error range of a second reference value that is less than the first reference value.

[0255] The instructions, when executed by the at least one processor individually or collectively, may further cause the refrigerator to apply the reference voltage to the at least one voltage control circuit to generate an electric field between the first electrode and the second electrode, based on the impedance change rate of the food being less than or equal to a threshold value after the compressor starts operating. The threshold value may be greater than the reference value.

[0256] The refrigerator may further include a food sensor configured to identify the food. The instructions, when executed by the at least one processor individually or collectively, may further cause the refrigerator to obtain food information corresponding to the identified food and electric field control information corresponding to the food information from the memory or a user device, and determine the on-off duty ratio of the frequency control circuit or the reference voltage applied to the at least one voltage control circuit based on the electric field control information.

[0257] The refrigerator may further include a direct current (DC) converter configured to apply a voltage to the RF power supply, and a power factor correction (PFC) circuit configured to deliver power factor compensated power to the DC converter. The at least one voltage control circuit may be connected to at least one of the DC converter or the PFC circuit.

[0258] According to an embodiment of the disclosure, in a method performed by a refrigerator including a storage compartment, an evaporator configured to cool the storage compartment, a compressor configured to supply a refrigerant to the evaporator, a first electrode arranged in the storage compartment, a second electrode arranged spaced apart from the first electrode in the storage compartment, a radio frequency (RF) power supply configured to apply an RF signal to the first electrode and the second electrode, a direct current (DC) converter configured to apply a voltage to the RF power supply, and a power factor correction (PFC) circuit configured to deliver power factor compensated power to the DC converter, the method may include: operating the compressor to supply the refrigerant to the evaporator so as to cool the storage compartment; identifying an impedance change rate of food placed between the first electrode and the second electrode, based on an output voltage between the first electrode and the second electrode and an output current of the first electrode, the output voltage and the output current being periodically detected by a voltage-current detector; and adjusting a reference voltage applied to at least one voltage control circuit configured to adjust an input voltage of the RF power supply, or an on-off duty ratio of a frequency control circuit configured to generate a switching signal for turning the RF power supply on or off, based on the impedance change rate of the food.

[0259] The adjusting of the reference voltage or the on-off duty ratio may include: adjusting the reference voltage applied to the at least one voltage control circuit, based on the impedance change rate of the food being greater than or equal to a reference value, and adjusting the on-off duty ratio of the frequency control circuit, based on the impedance change rate of the food being less than the reference value.

[0260] The adjusting of the reference voltage may include reducing the reference voltage to reduce the input voltage, based on a decrease in the impedance change rate of the food. The adjusting of the on-off duty ratio may include reducing the on-off duty ratio based on the decrease in the impedance change rate of the food.

[0261] The method may further include: adjusting a frequency of the switching signal, based on the impedance change rate of the food being less than the reference value.

[0262] The adjusting of the frequency of the switching signal may include reducing the frequency of the switching signal based on a decrease in the impedance change rate of the food.

[0263] The reference value may be a first reference value. The adjusting of the on-off duty ratio may include: maintaining the on-off duty ratio of the frequency control circuit to be constant, based on the impedance change rate of the food being within an error range of a second reference value that is less than the first reference value.

[0264] The method may further include applying the reference voltage to the at least one voltage control circuit to generate an electric field between the first electrode and the second electrode, based on the impedance change rate of the food being less than or equal to a threshold value after the compressor starts operating. The threshold value may be greater than the reference value.

[0265] The method may further include: identifying the food by a food sensor; and obtaining food information corresponding to the identified food and electric field control information corresponding to the food information from memory of the refrigerator or a user device. The adjusting of the reference voltage or the on-off duty ratio may include determining the on-off duty ratio of the frequency control circuit or the reference voltage applied to the at least one voltage control circuit based on the electric field control information.

[0266] According to the disclosure, a refrigerator and a method performed by the same may directly and precisely adjust a temperature of food using dielectric heating.

[0267] According to the disclosure, a refrigerator and a method performed by the same may not only refrigerate and freeze food, but also maintain the food in a non-frozen (supercooled) state and even defrost the food. In addition, the refrigerator and the method performed by the same may age the food.

[0268] According to the disclosure, a refrigerator and a method performed by the same may maintain food in a non-frozen (supercooled) state, and thus allowing the long-term storage of the food without deteriorating the quality of the food.

[0269] According to the disclosure, a refrigerator and a method performed by the same may defrost food, and thus when a user desires to cook the frozen food, the food may be cooked more quickly.

[0270] Meanwhile, the disclosed embodiments may be implemented in the form of a recording medium that stores instructions executable by a computer. The instructions may be stored in the form of program codes, and when executed by a processor, the instructions may create a program module to perform operations of the disclosed embodiments.

[0271] The machine-readable recording medium may be provided in the form of a non-transitory storage medium. Here, when a storage medium is referred to as non-transitory, it may be understood that the storage medium is tangible and does not include a signal (electromagnetic waves), but rather that data is semi-permanently or temporarily stored in the storage medium. For example, a non-transitory storage medium may include a buffer in which data is temporarily stored.

[0272] The methods according to the various embodiments disclosed herein may be provided in a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read only memory (CD-ROM)), or may be distributed through an application store (e.g., Play Store) online. In the case of online distribution, at least a portion of the computer program product may be stored at least semi-permanently or may be temporarily generated in a storage medium, such as memory of a server of a manufacturer, a server of an application store, or a relay server.

[0273] While the disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents.