Operation controlling apparatus and method of reciprocating compressor

Abstract

An operation controlling apparatus of a reciprocating compressor includes: a detector configured to detect a torque output by a motor of the reciprocating compressor, a rotation speed of the motor, a counter electromotive voltage of the motor, and a current applied to the motor; a controller configured to determine a mode switching time point for switching an operation mode of the reciprocating compressor based on the torque, the rotation speed, the counter electromotive voltage, and the current of the motor, and output a control signal for changing a wire ratio of the motor corresponding to the operation mode; and a driver configured to change the wire ratio of the motor based on the control signal and operate the reciprocating compressor in the operation mode among at least two operation modes.

Claims

1. An operation controlling apparatus of a reciprocating compressor, the reciprocating compressor being configured to operate based on changes in load, the operation controlling apparatus comprising: a detector configured to detect a torque output by a motor of the reciprocating compressor, a rotation speed of the motor, a counter electromotive voltage of the motor, and a current applied to the motor; a controller configured to: determine a mode switching time point for switching an operation mode of the reciprocating compressor based on the torque, the rotation speed, the counter electromotive voltage, and the current of the motor, and output a control signal for changing a wire ratio of the motor corresponding to the operation mode based on the mode switching time point; and a driver configured to change the wire ratio of the motor based on the control signal and operate the reciprocating compressor in the operation mode among at least two operation modes, wherein the operation mode of the reciprocating compressor comprises a power saving mode corresponding to a first wire ratio, a power mode corresponding to a second wire ratio, and a normal mode corresponding to a third wire ratio, wherein the second wire ratio is less than the first wire ratio, and wherein the third wire ratio is less than the first wire ratio and greater than the second wire ratio.

2. The operation controlling apparatus of claim 1, wherein the driver comprises the motor and an inverter, the inverter comprising a full-bridge type inverter that comprises three or more groups of devices, and wherein the motor comprises a wire-separated motor comprising two or more coils connected to each other electrically in series.

3. The operation controlling apparatus of claim 2, wherein each of the groups of devices corresponds to one of the coils of the motor.

4. The operation controlling apparatus of claim 2, wherein a number of the groups of devices is greater than a number of the coils of the motor, and wherein the driver further comprises a switch configured to switch the operation mode based on the mode switching time point.

5. The operation controlling apparatus of claim 2, wherein the inverter comprises at least six full-bridge type switching devices and at least six free-wheel diodes, each of the full-bridge type switching devices being connected to one of the free-wheel diodes electrically in parallel.

6. The operation controlling apparatus of claim 5, wherein the full-bridge type switching devices comprise at least one of an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field effect transistor (MOSFET), or a bipolar junction transistor (BJT).

7. The operation controlling apparatus of claim 5, wherein the controller is configured to selectively turn on or turns off each of the full-bridge type switching devices based on a phase width modulation (PWM) control with the control signal.

8. The operation controlling apparatus of claim 5, wherein the coils of the motor comprise a first coil and a second coil that are adjacent to each other, and wherein the groups of devices comprise: a first group connected to an end of the first coil by a first current line; a second group connected to an intermediate end between the first coil and the second coil by a second current line; and a third group connected to an end of the second coil by a third current line.

9. The operation controlling apparatus of claim 8, wherein the controller is configured to: control each of the full-bridge type switching devices to be turned on or turned off based on the control signal to thereby control current flow through the first coil, the second coil, or both; and switch the operation mode of the reciprocating compressor based on the current flow through the first coil, the second coil, or both.

10. The operation controlling apparatus of claim 2, wherein the two or more coils have wire ratios that are different from one another.

11. The operation controlling apparatus of claim 1, wherein the controller is configured to change the wire ratio among the first wire ratio, the second wire ratio, and the third wire ratio based on the counter electromotive voltage of the motor.

12. The operation controlling apparatus of claim 11, wherein the controller is configured to: in the power saving mode, control rotation of the motor based on the first wire ratio according to the counter electromotive voltage; in the power mode, control rotation of the motor based on the second wire ratio that is less than 50% of the first wire ratio; and in the normal mode, control rotation of the motor based on the third wire ratio that is between 50% of the first wire ratio and 100% of the first wire ratio.

13. The operation controlling apparatus of claim 11, wherein a rotation speed of motor in the power mode is greater than a rotation speed of the motor in the power saving mode, and wherein a rotation speed of the motor in the normal mode is greater than the rotation speed of the motor in the power saving mode and less than the rotation speed of the motor in the power mode.

14. The operation controlling apparatus of claim 13, wherein the second wire ratio is reduced from the first wire ratio to rotate the motor with the rotation speed of the motor in the power mode.

15. The operation controlling apparatus of claim 11, wherein the driver is connected to a direct current (DC)-link and receive a DC-link voltage from the DC-link, wherein the counter electromotive voltage is proportional to the rotation speed of the motor corresponding to a number of turns of the motor, wherein the counter electromotive voltage has a speed limit voltage corresponding to a limit number of turns of the motor in each of the power saving mode, the power mode, and the normal mode, and wherein the speed limit voltage is less than or equal to the DC-link voltage.

16. The operation controlling apparatus of claim 15, wherein the controller is configured to: in each of the power saving mode, the power mode, and the normal mode, detect (i) the limit number of turns of the motor based on a same torque and (ii) a time point at which the counter electromotive voltage and the current are changed; and determine the mode switching time point based on the time point at which the counter electromotive voltage and current are changed.

17. A method for controlling a reciprocating compressor, the reciprocating compressor being configured to operate based on changes in load, the method comprising: detecting torque output by a motor of the reciprocating compressor, a rotation speed of the motor, a counter electromotive voltage of the motor, and a current applied to the motor; determining a mode switching time point for switching an operation mode of the reciprocating compressor based on the torque, the rotation speed, the counter electromotive voltage, and the current of the motor; outputting a control signal for changing a wire ratio of the motor corresponding to the operation mode; and changing the wire ratio of the motor based on the control signal to thereby operate the reciprocating compressor in the operation mode among at least two operation modes, wherein the operation mode of the reciprocating compressor comprises a power saving mode corresponding to a first wire ratio, a power mode corresponding to a second wire ratio, and a normal mode corresponding to a third wire ratio, wherein the second wire ratio is less than the first wire ratio, and wherein the third wire ratio is less than the first wire ratio and greater than the second wire ratio.

18. The method of claim 17, wherein changing the wire ratio comprises changing the wire ratio among the first wire ratio, the second wire ratio, and the third wire ratio based on the counter electromotive voltage of the motor.

19. The method of claim 17, further comprising: operating a driver to change the wire ratio among the first wire ratio, the second wire ratio, and the third wire ratio based on the control signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a configuration diagram showing an example of an operation controlling apparatus of a reciprocating compressor.

(2) FIG. 2 is a configuration diagram showing a driver of an operation controlling apparatus in related art.

(3) FIGS. 3A and 3B are exemplary views showing examples of a current waveform in related art.

(4) FIG. 4 is a configuration diagram showing an example of a driver including an inverter of a reciprocating compressor according to the present disclosure.

(5) FIGS. 5A to 7B are exemplary views showing examples of operation modes performed by changing wire ratios by the driver to control operation of the reciprocating compressor in FIG. 4.

(6) FIG. 8 is a graph showing an example of a rotation speed of a motor with respect to a counter electromotive voltage detected by a detector.

(7) FIG. 9 is a view of an example of speed limit points with respect to the number of turns of a motor based on a same torque detected by a detector.

(8) FIG. 10 is a view of an example driver including an inverter of an example operation controlling apparatus of a reciprocating compressor.

DETAILED DESCRIPTION

(9) The above mentioned objects, features, and advantages of the present disclosure will be described in detail with reference to the accompanying drawings, so that those skilled in the art to which the present disclosure pertains may easily implement the technical idea of the present disclosure. In the description of the present disclosure, when it is determined that the detailed description of the known technology related to the present disclosure may obscure the gist of the present disclosure, the detailed description thereof will be omitted. Hereinafter, preferred implementations of the present disclosure will be described in detail with reference to the accompanying drawings. The same reference numeral is used to indicate the same or similar component in the figures.

(10) FIG. 1 is a configuration diagram of an example of an operation controlling apparatus of a reciprocating compressor.

(11) As shown in FIG. 1, an operation controlling apparatus 10 of the reciprocating compressor may include a driver 11 that drives a compressor 20 based on a control signal, a detector 12 that detects a current of a motor and/or a voltage of a motor of the compressor 20, an asymmetric current generator 13 that generates an asymmetric motor current using current offset for the detected current of the motor, and a controller 14 that generates the control signal to drive the compressor 20 based on the asymmetric current of the motor and/or the detected voltage of the motor.

(12) In some examples, the driver 11 may generate a motor driving signal S_PWM based on a control signal S_CON applied from the controller 14, and may apply the motor driving signal S_PWM to a linear compressor 20 to drive the compressor 20. The motor driving signal S_PWM may have a form of alternating current (AC) voltage or an alternating current (AC).

(13) In some cases, the driver 11 may include an inverter or a triac. In some cases, the driver 11 may include a motor having two or more coils.

(14) Hereinafter, an operation controlling apparatus of a reciprocating compressor according to some implementations of the present disclosure is described.

(15) FIG. 4 illustrates a circuit configuration and an operation of an operation controlling apparatus of a reciprocating compressor including a driver. For example, as shown in FIG. 1, the operation controlling apparatus of the reciprocating compressor includes a driver 11, a detector 12, an asymmetric current generator 13, and a controller 14. However, the components of the operation controlling apparatus of the reciprocating compressor are not limited to the illustrated implementation, and some components may be added, changed, or deleted as necessary.

(16) Referring to FIG. 4, a driver (e.g., the driver 11 in FIG. 1) may include a full-bridge type inverter 100 having three groups of devices 110, 120, and 130, and a motor 200 as shown in FIG. 4. Each group of devices may 110, 120, and 130 include two or more diodes and two or more switching devices.

(17) In FIG. 4, the full-bridge type inverter 100 includes the three groups of devices 110, 120, and 130. However, the number of groups is not limited thereto, and the full-bridge type inverter may include three or more groups. For ease of explanation, the full-bridge type inverter 100 having three groups is described. In particular, the operation controlling apparatus of the reciprocation compressor may use the three-group inverter IPM, and the above case is described based on one implementation. However, this is one implementation for ease of explanation, but is not limited thereto.

(18) In some implementations, the full-bridge type inverter 100 may include freewheel diodes D1 to D6 connected in parallel to six switching devices S1 to S6, respectively. Further, a first switching device S1 and a fourth switching device S4 are connected to each other in series to form a first group 110. Further, the second switching device S2 and the fifth switching device S5 are connected in series to each other to form a second group 120. Further, the third switching device S3 and the third switching device S3 are connected to each other in series to form a third group 130.

(19) The switching devices S1 to S6 may be at least one of an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field effect transistor (MOSFET), or a bipolar junction transistor (BJT).

(20) The inverter 100 may operate based on input of a control signal through the PWM applied from the controller 14. That is, the controller 14 selectively turns on or off the switching devices S1 to S6 to allow current to flow through the compressor 20 in the forward direction or the reverse direction. Detailed process thereof is described in detail below.

(21) The motor 200 may include a two-stage wire-separated motor including a first coil 210 and a second coil 220 connected to each other electrically in series. However, the present disclosure is not limited thereto and may include a three-stage or more of wire-separated motor. The first coil 51 and the second coil 52 may have different wire ratios from each other.

(22) A first current line may connect the first group 110 (the node provided between S1 and S4) of the inverter 100 to the front end (a first end) (a) of the first coil 210 of the motor 200. A second current line may connect the second group 120 (the node provided between S2 and S5) of the inverter 100 to an intermediate end (a second end) (b) to which the first coil 210 and the second coil 220 of the motor 200 are connected. A third current line may connect the third group 130 (the node provided between S3 and S6) of the inverter 100 to the rear end (a third end) (c) of the second coil 220.

(23) In some implementations, the inverter 100 may include six switching devices S1 to S6 that have a full-bridge shape and that are controlled (turned on or turned off) based on a control signal of the controller 14. The reciprocating compressor may operate in the third-stage operation mode so that the current flow is changed to the first coil 210 or the second coil 220, or the first coil 210 and the second coil 220 of the motor 200.

(24) The three-stage operation mode may be classified into a high efficiency mode (a power saving mode), a normal mode, and an overload response mode (the power mode).

(25) The high efficiency mode (the power saving mode) is used in a section in which the motor 200 has a low rotation speed and the overload response mode (the power mode) is used when the motor 200 has high rotation speed. The normal mode is used in a section in which the motor 200 has an intermediate speed between the low speed and the high speed of the motor.

(26) The operation mode is implemented by changing the wire ratio of the motor.

(27) That is, in a section in which the counter electromotive voltage is low, the wire ratio thereof is changed to have a greater value in consideration of the counter electromotive force in the high efficiency mode (the power saving mode). Further, in a high speed section in which the counter electromotive voltage is high, the wire ratio thereof is changed to have a less value in consideration of the counter electromotive force in the overload response mode (the power mode). For example, in the overload response mode (the power mode), the wire ratio thereof less than 50% may be provided, compared to the high efficiency mode (the power saving mode), so that the controlling is performed to lower the counter electromotive force and to increase the current.

(28) In some examples, the wire ratio of the motor in the normal mode may be changed to be greater than 50% and less than 100% of the wire ratio in the power saving mode. The wire ratio is not limited thereto and may be changed depending on the operation mode or the designer.

(29) Thus, in the overload response mode (the power mode), the wire ratio thereof is reduced as much as the insufficient voltage to increase the current, to compensate for the voltage for high speed rotation, and to lower the counter electromotive voltage and prevent the voltage shortage.

(30) To change the wire ratio thereof in each mode, the controller 14 controls (turns on or turns off) six full-bridge type switching devices (S1 to S6) to change the flow of current to flow through the first coil 210 or the second coil 220, or the first coil 210 and the second coil 220 of the motor 200.

(31) That is, the controller 14 controls (turn-on or turn-off) the six full-bridge type switching devices S1 to S6 to control the operation of the reciprocating compressor in the high efficiency mode (the power saving mode), so that the flow of current flowing through the inverter 30 may be changed so that the current flows through the first coil 210 and the second coil 220 of the motor 200.

(32) Further, the controller 14 may control the six full-bridge switching devices S1 to S6 to control the operation of the reciprocating compressor in the normal mode, so that the flow of current flowing through the inverter 300 may be changed to flow through the second coil 220 of the motor 200.

(33) Further, the controller 14 may control the six full-bridge type switching devices (S1 to S6) to control the operation of the reciprocating compressor in the overload response mode (the power mode), so that the flow of the current flowing through the inverter 30 may be changed so that the current only flows through the first coil 210 of the motor 200.

(34) The controller 14 may determine a time point at which the mode is switched based on the torque, rotation speed, counter electromotive voltage, and current of the motor detected by the detector 12, to detect a time point at which the operation of the reciprocating compressor is controlled in the high efficiency mode (the power saving mode), the normal mode, and the overload response mode (the power mode).

(35) FIG. 8 shows an exemplary diagram corresponding to a graph showing a rotation speed of a motor with respect to a counter electromotive voltage detected by a detector. FIG. 9 is an exemplary diagram corresponding to a graph showing a limit point of speed with respect to changes of the number of turns of motor based on the same torque detected by a detector.

(36) As shown in FIG. 8, the counter electromotive voltage E is proportional to the rotation speed of the motor and the number of turns of the motor. At this time, the limit point of the speed of the motor with respect to the number of turns of the motor in each mode may not be greater than a DC link voltage.

(37) According to such a condition, as shown in FIG. 9, the limit point of the speed with respect to the changes in the number of turns of the motor based on the same torque, a time point in which the counter electromotive voltage and the current are changed may be detected in advance.

(38) Accordingly, the controller 14 may determine the time point at which the mode is switched based on the time point at which the counter electromotive voltage and the current are changed.

(39) The above-described operation and action of the driver for the operation control of the reciprocating compressor as described above is described below in detail.

(40) FIGS. 5A to 7B are exemplary diagrams showing operation modes performed by changing, by drivers, a wire ratio of a motor to control operation of the reciprocating compressor in FIG. 4. FIGS. 5A and 5B are exemplary diagrams showing examples of current flow when the reciprocating compressors operate in the high efficiency mode (the power saving mode). FIGS. 6A and 6B are exemplary diagrams showing examples of current flow when the reciprocating compressors operate in the normal mode. Further, FIGS. 7A and 7B are exemplar diagrams showing examples of current flow when the reciprocating compressors operate in the overload response mode (the power mode).

(41) Referring to FIGS. 5A and 5B, in the high efficiency mode (the power saving mode), the six full-bridge switching devices S1 to S6 are controlled (turned on or turned off) so that the current flow is changed so that the current flowing through the inverter 100 flows through the first coil and the second coil 220a.

(42) The inverter 100 may operate based on the input of the control signal through the PWM applied to the controller 14. Thus, the applied control signal has a section in which the control signal has a positive value and a section in which the control signal has a negative value.

(43) In some examples, as shown in FIG. 5A, the current flows in the forward direction, in the section in which the control signal has the positive value, and the controller 14 turns on the first switching device S1 and the sixth switching device S6 and turns off the remaining switching devices S2 to S5 among six full-bridge type switching devices S1 to S6.

(44) By contrast, as shown in FIG. 5B, the current flows in the reverse direction, in a section in which the control signal has negative value, and the controller 14 turns on the third switching device S3 and the fourth switching device S4 and turns off the remaining switching devices S1, S2, S5, and S6 among the six full-bridge type switching devices S1 to S6.

(45) Through this switching, the driver 11 may change the current flow flowing through the inverter 100 so that the current flowing through the inverter 100 flows through the first coil and the second coil 200a of the motor 200.

(46) As shown in FIGS. 6A and 6B, in the normal mode, the six full-bridge type switching devices S1 to S6 is controlled (turned on or turned off) based on the control signal of the controller 14, so that the current flow is changed so that the current only flows through the second coil 220b of the motor 200.

(47) The inverter 100 may operate based on the input of the control signal through the PWM applied by the controller 14. Thus, the applied control signal has a section in which the control signal has a position value and a section in which the control signal has a negative value.

(48) In some examples, as shown in FIG. 6A, when the control signal is in a section in which the control signal has the positive value, the current flows in the forward direction, and the controller 14 turns on the second switching device S2 and the sixth switching device S6 and turns off the remaining switching devices S1 and S3 to S5 among the six full-bridge type switching devices S1 to S6.

(49) By contrast, as shown in FIG. 6B, the current flows in the reverse direction in a section in which the control signal has the negative value, the controller 14 turns on a third switching device S3 and a fifth switching device S5 and turns of the remaining switching devices S1, S2, S4, and S6 among six full-bridge type switching devices S1 to S6.

(50) The driver 11 may change the current flow so that the current flowing through the inverter 100 flows through the second coil 200b.

(51) As shown in FIGS. 7A and 7B, in the overload response mode (the power mode), six full-bridge type switching devices S1 to S6 are controlled (turned on or turned off) based on the control signal of the controller 14, so that the current that has flowed through the inverter 30 only flows through the first coil 200c of the motor 200.

(52) At this time, the inverter 100 operates based on the input of the control signal through the PWM applied by the controller 14. Thus, the applied control signal has a section in which the control signal has a positive value and a section in which the control signal has a negative value.

(53) In some examples, as shown in FIG. 7A, when the control signal is in a section in which the control signal has a positive value, the current flows in the forward direction, and the controller 14 turns on the first switching device and the fifth switching device S5 and turns off the remaining switching devices S2 to S4 and S6, among the six full-bridge type switching devices S1 to S6.

(54) By contrast, as shown in FIG. 7B, the current flows in the reverse direction in a section in which the control signal has the negative value, the controller 14 turns on the second switching device S2 and the fourth switching device S4 and turns off the remaining switching devices S1, S3, S5, and S6, among six full-bridge type switching devices S1 to S6.

(55) The driver 11 may change the current that has flowed through the inverter 100 to flow only into the first coil 210 of the motor 200 through switching.

(56) FIG. 10 is a configurational view of an example driver, showing operation of the driver including an inverter in an operation controlling apparatus of a reciprocating compressor.

(57) FIG. 10 shows a driver 11 including a full-bridge type inverter 100 and a motor 200.

(58) FIG. 10 is different from FIG. 4 in that FIG. 10 shows a full-bridge type inverter 100 including n-number of groups 110, 120, 130, 140, and 150 while FIG. 4 shows a full-bridge type inverter 100 including three groups 110, 120, and 130.

(59) As shown in FIG. 4, the driver 11 includes a two-stage wire-separated motor 200 including the first coil 210 and the second coil 220 connected in series. As shown in FIG. 10, the driver 11 includes the three-stage wire-separated motor 200 including the first coil 210, the second coil 220, and the third coil 230. The number of coils including the three-stage wire-separated motor 200 is increased compared to the number of coils including the two-stage wire-separated motor 200.

(60) In some implementations, as shown in FIG. 10, the number of groups of the inverter 100 and the number of coils of the motor 200 may be increased to four, five, or more.

(61) In some implementations, the method for controlling operation of the inverter 100 in which the number of groups is increased and the motor 200 in which the number of coils is increased has the same or similar technical idea as or to the method for controlling the operation of the inverter 100 and the motor 200 shown in FIG. 4. Thus, details of the method for controlling the operation of the inverter 100 in which the number of groups is increased and the motor 200 in which the number of coils is increased are omitted.

(62) As described above, in the inverter 100 in which the number of groups is increased and the motor 200 in which the number of coils is increased, groups 110, 120, 130, 140, and 150 of the inverter 100 may correspond to coils 210, 220, and 230, but is not limited thereto. The number of groups 110, 120, 130, 140, and 150 of the inverter 100 may be greater than the number of coils 210, 220, and 230 of the motor. In this case, as shown in FIG. 2, the switch 40 may be further used to switch the mode.

(63) While the present disclosure has been described with reference to exemplary drawings thereof, it is to be understood that the present disclosure is not limited to implementations and drawings in the present disclosure, and various changes can be made by the skilled person in the art within the scope of the technical idea of the present disclosure. Although working effects obtained based on configurations of the present disclosure are not explicitly described while describing the implementations of the present disclosure, effects predictable based on the configurations have also to be recognized.