Domestic Refrigeration Device With A Coolant Circuit, And Method For Operating A Domestic Refrigeration Device With A Coolant Circuit

Abstract

A domestic refrigeration device and a method for operating a domestic refrigeration device. The domestic refrigeration device has a heat-insulated body with a coolable inner container which delimits a coolable interior provided for storing food. A coolant circuit is provided for cooling the coolable interior and includes a compressor and a field-oriented electric drive. The field-oriented electric drive has a field-oriented controller, a converter, and a permanently excited synchronous motor which is connected downstream of the converter and which is part of the compressor or is provided for driving the compressor.

Claims

1-10. (canceled)

11. A method for operating a domestic refrigeration appliance, the appliance having: a thermally insulated body with a coolable inner container delimiting a coolable interior chamber for storing food, a refrigerant circuit for cooling the coolable interior chamber with a compressor and a controlled electric drive; wherein the controlled electric drive has a field-oriented controller, a converter and a permanently excited three-phase synchronous motor, which is connected downstream of the converter and which is part of the compressor or configured to drive the compressor; wherein the field-oriented controller has a first current control circuit configured to control a transverse current generating a main torque of the permanently excited three-phase synchronous motor, a second current control circuit configured to control a longitudinal current for the permanently excited three-phase synchronous motor and a speed control circuit super ordinate to the first and second current control circuits, the speed control circuit generating a transverse current target value for the first current control circuit as a function of a predetermined target speed for the permanently excited three-phase synchronous motor and an actual speed of the permanently excited three-phase synchronous motor, and wherein output signals of the first and second current control circuits are provided at least indirectly to activate the converter; the method comprising the following method steps: for starting up the permanently excited three-phase synchronous motor from standstill, implementing a target speed for the field-oriented controller as a function of a cooling requirement for the coolable interior chamber; and approaching a longitudinal current target value provided for the second current control circuit or its magnitude starting from zero to a predetermined value within a first time period according to a predetermined profile, to cause the permanently excited three-phase synchronous motor to generate an additional torque to the main torque due to a resulting longitudinal current, so that an overall torque of the permanently excited three-phase synchronous motor is greater than the main torque.

12. The method according to claim 11, wherein the first current control circuit has a first current controller and the second current control circuit has a second current controller and an input signal for the first current controller is a deviation of the transverse current actual value from the transverse current target value and an input signal for the second current controller is a deviation of the longitudinal current actual value from the longitudinal current target value.

13. The method according to claim 11, which comprises adjusting the longitudinal current target value or a magnitude thereof in a ramp shape during the first time period and which comprises storing an adjustment profile in a look-up table or determining the adjustment profile by way of a mathematical formula.

14. The method according to claim 11, which comprises adjusting the longitudinal current target value or a magnitude thereof in accordance with an adjustment profile stored in a look-up table or determined by way of a mathematical formula.

15. The method according to claim 11, which further comprises: reducing the longitudinal current target value or a magnitude thereof to zero as soon as the permanently excited three-phase synchronous motor reaches a stable working point or after a predetermined second time period; and subsequently operating the field-oriented controller with a longitudinal current target value equal to zero.

16. The method according to claim 14, which comprises reducing the longitudinal current target value or the magnitude thereof from a predetermined value to zero within a predetermined third time period according to a predetermined profile.

17. A domestic refrigeration appliance, comprising: a thermally insulated body with a coolable inner container delimiting a coolable interior chamber for storing food; a refrigerant circuit configured to cool said coolable interior chamber, said refrigerant circuit including a compressor and a field-oriented electric drive, which has a field-oriented controller, a converter and a permanently excited three-phase synchronous motor, which is connected downstream of said converter and which forms part of said compressor or is configured to drive said compressor; said field-oriented controller having a first current control circuit provided to control a transverse current generating a main torque of said permanently excited three-phase synchronous motor, a second current control circuit provided to control a longitudinal current for said permanently excited three-phase synchronous motor and a speed control circuit super ordinate of said first and second current control circuits, said speed control circuit generating a transverse current target value for said first current control circuit as a function of a predetermined target speed for said permanently excited three-phase synchronous motor and an actual speed of said permanently excited three-phase synchronous motor; said first and second current control circuits carrying output signals for directly or indirectly activating said converter, and wherein: for starting up said permanently excited three-phase synchronous motor from standstill, a target speed for said field-oriented controller is determined as a function of a cooling requirement for said coolable interior chamber, and a longitudinal current target value for said second current control circuit or a magnitude thereof is adjusted starting from zero to a predetermined value within a first time period according to a predetermined profile, to cause said permanently excited three-phase synchronous motor to generate an additional torque to the main torque due to the resulting longitudinal current, so that an overall torque of said permanently excited three-phase synchronous motor is greater than the main torque.

18. The domestic refrigeration appliance according to claim 17, wherein said first current control circuit has a first current controller and said second current control circuit has a second current controller and an input signal for said first current controller is a deviation of the transverse current actual value from the transverse current target value and an input signal for said second current controller is a deviation of the longitudinal current actual value from the longitudinal current target value.

19. The domestic refrigeration appliance according to claim 17, wherein an adjustment of the longitudinal current target value or the magnitude thereof is ramp-like during the first time period and/or wherein a profile of the adjustments is stored in a look-up table or is calculated by way of a mathematical formula.

20. The domestic refrigeration appliance according to claim 17, wherein the longitudinal current target value or the magnitude thereof is decreased to zero as soon as said permanently excited three-phase synchronous motor reaches a stable working point or after a predetermined second time period, and wherein the field-oriented controller is subsequently operated with a longitudinal current target value equal to zero.

21. The domestic refrigeration appliance according to claim 20, wherein the longitudinal current target value or the magnitude thereof is reduced from its predetermined value to zero within a predetermined third time period according to a predetermined profile.

Description

[0032] An exemplary embodiment of the invention is shown by way of example in the accompanying schematic drawings, in which:

[0033] FIG. 1 shows a perspective view of a domestic refrigeration appliance,

[0034] FIG. 2 shows a refrigerant circuit of the domestic refrigeration appliance,

[0035] FIG. 3 shows an electric drive controlled in a field-oriented manner for the compressor of the refrigerant circuit, and

[0036] FIG. 4 shows a part of the current controller of the field-oriented controller.

[0037] FIG. 1 shows a perspective view of a domestic refrigeration appliance 1, which comprises a thermally insulated carcass 10 with an inner container 2, which delimits a coolable interior chamber 3. The coolable interior chamber 3 is provided for storing food (not shown in detail).

[0038] In the present exemplary embodiment the domestic refrigeration appliance 1 has a pivotable door leaf 4 for closing the coolable interior chamber 3. The door leaf 4 is mounted in particular in such a manner that it can pivot in relation to a vertical axis. The coolable interior chamber 3 is accessible when the door leaf 4 is open, as shown in FIG. 1.

[0039] In the present exemplary embodiment a number of door trays 5 for storing food are arranged on the face of the door leaf 4 facing in the direction of the coolable interior chamber 3. In particular a number of compartment bases 6 for storing food are arranged in the coolable interior chamber 3 and in particular a drawer 7, in which food can also be stored, is arranged in the lower region of the coolable interior chamber 3.

[0040] The domestic refrigeration appliance 1 comprises a refrigerant circuit 20, shown in FIG. 2, for cooling the coolable interior chamber 3. In the present exemplary embodiment the refrigerant circuit 20 of the coolable interior chamber 3 comprises a compressor 21, a condenser 22 connected downstream of the compressor 21, a restrictor apparatus 23 connected downstream of the condenser 22, which is embodied in particular as a restrictor tube or capillary tube, and an evaporator 24, which is arranged between the restrictor apparatus 23 and the compressor 21. The compressor 21 is preferably arranged within a machine chamber of the domestic refrigeration appliance 1, which is located in particular behind the drawer 7.

[0041] In the present exemplary embodiment the domestic refrigeration appliance 1 comprises an electronic control apparatus 8, which is designed to activate the refrigeration apparatus, in particular the compressor 21 of the refrigerant circuit 20, in a manner generally known to the person skilled in the art in such a manner that the coolable interior chamber 3 has at least roughly a predetermined or predeterminable target temperature. The electronic control apparatus 8 is preferably designed such that it controls the temperature of the coolable interior chamber 3. In order to obtain the actual temperature of the coolable interior chamber 3 if required, the domestic refrigeration appliance 1 can have at least one temperature sensor (not shown in detail) connected to the electronic control apparatus 8.

[0042] In order to activate or control the refrigerant circuit 20, the domestic refrigeration appliance comprises a controlled electric drive 30, as shown in FIG. 3, which has a permanently excited three-phase synchronous motor, which is preferably embodied as a brushless direct current motor 31. The brushless direct current motor 31 is coupled to the compressor 21 or is part of the compressor 21 and drives this as required according to a target speed n.sub.tar predetermined by the electronic control apparatus 8. The target speed n.sub.tar is calculated or predetermined in particular by the electronic control apparatus 8 based on an intended cooling of the coolable interior chamber 3, for example based on the current temperature and the target temperature of the coolable interior chamber 3.

[0043] The controlled electric drive 30 comprises a controlling element for driving the brushless direct current motor 31. The controlling element is embodied as a converter 32 and generates a three-phase or multiphase voltage during operation of the electric drive 30, the fundamental oscillation of said voltage having a fundamental frequency and amplitude which are an indirect function of the target speed n.sub.tar and an actual speed n.sub.act of the brushless direct current motor 31.

[0044] In the present exemplary embodiment the controlled electric drive 30 has measurement apparatuses 33, which are used to measure the electric phase currents i.sub.1,2,3 of the brushless direct current motor 31 and to determine the actual speed. The measurement apparatuses 33 edit the determined actual speed n.sub.act and the measured electric phase currents i.sub.1,2,3 of the brushless direct current motor 31 as required, so that the determined actual speed n.sub.act and the measured electric phase currents i.sub.1,2,3 of the brushless direct current motor 31 can be processed by a field-oriented controller 34 of the controlled electric drive 30 in a suitable form. The actual speed n.sub.act can be determined for example, as provided for in the present exemplary embodiment, from the measured phase currents i.sub.1,2,3. The actual speed n.sub.act can however also be measured directly using an appropriate sensor.

[0045] In the present exemplary embodiment the control of the controlled electric drive 30 is based on field-oriented control. The principal control structure of such control is known for example from DE 102 06 191 B4, as cited in the introduction. The essential difference between the field-oriented control of the electric drive 30 and conventional field-oriented control is the predetermination of the target values for the longitudinal current i.sub.d during operation of the domestic refrigeration appliance 1, in particular for starting up the compressor 21 or the brushless direct current motor 31.

[0046] The field-oriented controller 34 forms a cascade structure with internal current control circuits, on which an external speed control circuit is superimposed.

[0047] A control structure in which the transformed transverse and longitudinal currents i.sub.q, i.sub.d are controlled by means of the current control circuits results for field-oriented control. In the present exemplary embodiment the current control circuits preferably comprise a first current controller 41 for the transverse current i.sub.q and a second current controller 41 for the longitudinal current i.sub.d. The two current controllers 41, 42 are in particular PI controllers.

[0048] In the present exemplary embodiment the field-oriented controller 34 is embodied in such a manner that it transforms the phase currents i.sub.1,2,3 of the brushless direct current motor 31 into fixed-rotor longitudinal and transverse current actual values i.sub.s,d, i.sub.s,q relating to the rotor of the brushless direct current motor 31. The deviation between the target value i.sub.q,tar of the transverse current i.sub.q and the transverse current actual value i.sub.s,q is the input signal for the first current controller 41 and the deviation between the longitudinal current target value i.sub.d,tar and the longitudinal current actual value i.sub.s,d is the input signal for the second current controller 42.

[0049] The output signals of the two current controllers 41, 42 correspond to transformed electric voltages u.sub.q, u.sub.d, which are transformed by means of a transformation (not shown but known in principle to the person skilled in the art) into signals suitable for activating the converter 32.

[0050] In the present exemplary embodiment the transverse current target value i.sub.q,tar results from this external speed control circuit, which is calculated as a function of the target speed n.sub.tar and the actual speed n.sub.act, in particular as a function of the speed deviation n.sub.dev, which results from the measured and predetermined target speed n.sub.tar.

[0051] In the present exemplary embodiment the speed control circuit comprises a speed controller 43, which is preferably embodied as a PI controller. The output signal of the speed controller 43 is the transverse current target value i.sub.q,tar.

[0052] The brushless direct current motor 31 is embodied in such a manner that the longitudinal current i.sub.d is also able to form a torque-forming component, which acts in addition to the main torque generated by the transverse current i.sub.q with a corresponding longitudinal current i.sub.d. It is thus possible to increase the overall torque above the main torque of the brushless direct current motor 31 with a corresponding longitudinal current i.sub.d.

[0053] In the present exemplary embodiment the domestic refrigeration appliance 1 is embodied in such a manner that it generates different longitudinal current target values i.sub.d,tardepending on the operating mode. The longitudinal current target values i.sub.d,tar are preferably saved in a look-up table, which is stored in particular in the electronic control apparatus 8, or are determined by means of a mathematical equation.

[0054] The decision as to which longitudinal current target value i.sub.d,tar is currently applicable is illustrated in FIG. 4 by a function block 44, which actuates a function switch 45.

[0055] As the compressor 21 starts up, in other words as the stationary brushless direct current motor 31 starts up to a target speed n.sub.tar in the present exemplary embodiment the electronic control apparatus 8 first predetermines the target speed n.sub.tar for the brushless direct current motor 31. The controlled electric drive 30 is also first operated in a start-up mode, as illustrated functionally by function blocks AF1 and AF2 in FIG. 4.

[0056] In start-up mode the longitudinal current target value i.sub.d,tar or its magnitude is first increased constantly starting from zero according to a predetermined profile, until the longitudinal current target value i.sub.d,tar or its magnitude reaches a predetermined value. The longitudinal current target value i.sub.d,tar here is selected such that as a result the brushless direct current motor 31 generates an additional torque to the main torque generated by the transverse current i.sub.q, said additional torque becoming ever larger due to the constantly increasing longitudinal current i.sub.d, so that the overall torque of the brushless direct current motor 31 is greater than the main torque. The profile of the constant increasing is permanently predetermined and is preferably stored in the look-up table.

[0057] The longitudinal current target value i.sub.d,taror its magnitude is preferably increased in a ramp-like manner starting from zero, as shown by the function block AF1. For this part of start-up mode the function block 44 switches the function switch 45 to a switch position A1.

[0058] In the present exemplary embodiment the increasing of the longitudinal current target value i.sub.d,tar or its magnitude is time controlled, in other words the longitudinal current target value i.sub.d,taror its magnitude reaches its predetermined value after a predetermined first time period T.sub.1. When said predetermined value is reached, the vectors of the longitudinal current i.sub.d and the vector of the transverse current i.sub.q have a defined angle in the settled or adjusted state.

[0059] In the present exemplary embodiment provision is made for the longitudinal current target value to be set to zero after the end of start-up mode, in particular when the brushless direct current motor 31 reaches a stable working point and in particular is to be operated at a relatively low speed or at a speed below the maximum speed of preferably less than 0.6 times the maximum speed. This is illustrated by a function block N in FIG. 4.

[0060] The stable working point is reached for example when the speed deviation n.sub.dev, which results from the measured actual speed n.sub.actand the predetermined target speed n.sub.tar, is below a predetermined value.

[0061] In the present exemplary embodiment provision is however also made for the longitudinal current target value i.sub.d,tar to be set to zero after a predetermined second time period T.sub.2 after the end of the first time period T.sub.1. When the longitudinal current target value i.sub.d,tar is set to zero, the function switch 45 is switched to a switch position B.

[0062] In the present exemplary embodiment however the longitudinal current target value i.sub.d,tar is not set to zero abruptly but is returned constantly from its predetermined value to zero. This is preferably carried out within a predetermined third time period T.sub.3. The longitudinal current target value i.sub.d,taror its magnitude is preferably reduced in a ramp-like manner starting from the predetermined value, as shown by ii the function block AF2.

[0063] For this part of start-up mode the function block 44 switches the function switch 45 to a switch position A2.

[0064] In the present exemplary embodiment provision is also made for the brushless direct current motor 31 to be able to be operated at a higher speed. To achieve this, the electric drive 30 can be operated in a field weakening mode, as shown by a function block FS in FIG. 4. The field weakening mode of a permanently excited three-phase synchronous motor is known in principle to the person skilled in the art and is therefore not described here.

[0065] In field weakening mode a field-counteracting current is injected into the brushless direct current motor 31. To this end the longitudinal current target value i.sub.d,tar is selected to be smaller than zero. For field weakening mode the function switch 45 is switched to a switch position D.

LIST OF REFERENCE CHARACTERS

[0066] 1 Domestic refrigeration appliance [0067] 2 Inner container [0068] 3 Coolable interior chamber [0069] 4 Door leaf [0070] 5 Door tray [0071] 6 Compartment bases [0072] 7 Drawer [0073] 8 Electronic control apparatus [0074] 10 Carcass [0075] 20 Refrigerant circuit [0076] 21 Compressor [0077] 22 Condenser [0078] 23 Restrictor apparatus [0079] 24 Evaporator [0080] 30 Controlled electric drive [0081] 31 Brushless direct current motor [0082] 32 Converter [0083] 33 Measurement apparatuses [0084] 34 Field-oriented controller [0085] 41, 42 Current controller [0086] 43 Speed controller [0087] 44 Function block [0088] 45 Function switch [0089] AF1, AF2 Function block [0090] A1, A2, B, C Switch position [0091] FS, N Function block [0092] i.sub.s,d Longitudinal current actual value [0093] i.sub.s,q Transverse current actual value [0094] i.sub.q,tar Transverse current target value [0095] i.sub.d,tar Longitudinal current target value [0096] i.sub.1,2,3 Phase currents [0097] n.sub.tar Target speed [0098] u.sub.q, u.sub.d Transformed electric voltages [0099] n.sub.dev Speed deviation