JP2013211954A - Motor control method, control circuit for motor, motor with power supply module, compressor, and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control method and control circuit for motor, capable of preventing degradation in the utilization rate of a voltage while omitting a smoothing capacitor.SOLUTION: The phase of an output voltage of a periodically changing AC-DC converter circuit is identified. The phase of the rotation of a motor is identified. The rotational speed of the motor is controlled, so that the phase of the rotation is made to coincide with the phase of the output voltage.

Description

  The present invention relates to an electric motor control method, an electric motor control circuit, an electric motor with a power supply module using the control method and the control circuit, a compressor, and an air conditioner.

  For example, an electric motor incorporated in a compressor is generally known. An inverter circuit is used for driving the electric motor. An AC / DC conversion circuit is connected to the inverter circuit. The output voltage of the AC / DC conversion circuit pulsates according to the periodic fluctuation of the AC voltage. When a smoothing capacitor is connected to the AC / DC conversion circuit, the output voltage of the AC / DC conversion circuit is smoothed.

JP-A-10-150795

  As disclosed in Patent Document 1, an attempt to omit a smoothing capacitor is sought. When the smoothing capacitor is omitted, a pulsating DC voltage is supplied to the inverter circuit. An attempt is made to smooth the output voltage based on the switching operation of the inverter circuit. The output voltage cannot be smoothed by the maximum output of the AC / DC conversion circuit, and the voltage utilization rate decreases.

  According to some aspects of the present invention, it is possible to provide a motor control method and a motor control circuit that can prevent a decrease in voltage utilization rate while omitting a smoothing capacitor.

  One aspect of the present invention includes a step of specifying a phase of an output voltage of an AC / DC conversion circuit that varies periodically, a step of specifying a phase of rotation of an electric motor, and the output by controlling the rotation speed of the electric motor. And a step of adjusting the rotation phase to a voltage phase.

  Thus, the periodic variation of the output voltage and the phase of rotation are matched. Since the rotation phase is synchronized with the periodic variation of the load torque, the periodic variation of the output voltage and the periodic variation of the load torque can be synchronized. As a result, adjustment of the output voltage can be omitted. Irregular rotation of the electric motor can be suppressed regardless of fluctuations in the load torque. The smoothing capacitor is omitted. Since the periodic fluctuation of the output voltage is used to eliminate the rotation unevenness, the output voltage can be used to the maximum without being discarded. A decrease in the voltage utilization factor can be prevented.

  The method for controlling the electric motor can include a step of specifying a zero cross of the output voltage and a step of checking the time of the zero cross against the rotation of the electric motor when the phase is adjusted. The load torque of the electric motor fluctuates within one rotation of the rotor, and the fluctuation is repeated every rotation. Such fluctuations in load torque can be specified in advance. For example, if the zero crossing of the output voltage is adjusted to the rotational position of the minimum load torque, the periodic fluctuation of the output voltage and the periodic fluctuation of the load torque can be synchronized. As a result, the rotational unevenness can be prevented to the maximum.

  The method for controlling the electric motor includes a step of maintaining synchronization between the output voltage and the rotation, and a phase shift between the output voltage and the rotation is detected while the synchronization is maintained. And a step of increasing / decreasing the number of rotations of the electric motor from the number of rotations matching the cycle. When the rotational speed increases or decreases in this way, the phase of the motor rotation deviates from the phase of the output voltage. If the rotation speed is restored to the rotation speed that matches the output voltage when the rotation phase matches the output voltage phase, the rotation of the motor is synchronized with the output voltage period while maintaining the phase match with the output voltage. can do. The phase shift between output voltage and rotation can be eliminated.

  According to another aspect of the present invention, a first port that receives a first signal that specifies a phase of an output voltage of an AC / DC conversion circuit that varies periodically, and a second signal that specifies a phase of rotation of an electric motor. The present invention relates to a control circuit for an electric motor comprising two ports and an arithmetic circuit connected to the first port and the second port and controlling the rotational speed of the electric motor to adjust the phase of the rotation to the phase of the output voltage. Such a control circuit for an electric motor can be used to realize the above-described control method.

  According to another aspect of the present invention, a first detection circuit that detects a phase of an output voltage of an AC / DC conversion circuit that varies periodically, a second detection circuit that detects a phase of a rotor, and the first detection circuit And an arithmetic circuit connected to the second detection circuit and including an arithmetic circuit that controls the number of rotations of the rotor and adjusts the phase of the rotor to the phase of the output voltage. In such an electric motor with a power supply module, the aforementioned control method can be easily realized.

  An electric motor with a power supply module can be used by being incorporated in a compressor. At this time, the compressor may include an electric motor with a power supply module and a piston that is connected to the electric motor with the power supply module and partitions the compression chamber in the piston chamber. The compressor can be used by being incorporated in an air conditioner.

It is a vertical sectional view showing roughly the structure of the compressor concerning one embodiment. It is a horizontal fragmentary sectional view along line 2-2 in FIG. It is a circuit diagram which shows roughly the control system of an electric motor. It is a figure which shows an example of the load characteristic of the compressor which concerns on this embodiment. It is a flowchart which shows operation | movement of a control circuit. It is a flowchart which shows operation | movement of a control circuit. It is a time chart which shows the mode of control concerning this embodiment roughly. It is a lineblock diagram showing roughly the composition of the air harmony device concerning one embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 schematically shows a compressor 11 according to an embodiment. The compressor 11 includes a housing 12. The housing 12 defines a sealed space 13. The sealed space 13 is airtightly separated from the external space. A first suction pipe 14a, a second suction pipe 14b, and a discharge pipe 15 are connected to the housing 12. The gas can flow into the sealed space 13 from the first and second suction pipes 14a and 14b. The gas in the sealed space 13 can be discharged from the discharge pipe 15 to the outside of the sealed space.

  An electric motor 16 and a compression unit 17 are disposed in the sealed space 13. The electric motor 16 includes a drive shaft 18. The drive shaft 18 is rotatably supported by the support plate 19. A bearing 21 is formed on the support plate 19 for support. The support plate 19 is fixed to the housing 12. Thus, the drive shaft 18 is rotatably attached to the housing 12.

  The electric motor 16 includes a rotor 22 and a stator 23. The rotor 22 is fixed to the drive shaft 18. The rotor 22 has a magnetic pole 24. The magnetic pole 24 can be composed of, for example, a permanent magnet. The stator 23 is arranged around the axis of the drive shaft 18. The stator 23 is fixed to the housing 12. The stator 23 has a magnetic pole 25. The magnetic pole 25 can be constituted by an inductor, for example. A rotational driving force can be generated on the drive shaft 18 by the interaction between the magnetic poles 24 and 25.

  The compression unit 17 includes a cylinder 26. The cylinder 26 is fixed to the housing 12. The cylinder 26 includes an upper member, an annular first intermediate member 27, a partition plate 28, an annular second intermediate member 29, and a lower member 31. Here, the first intermediate member 27 is sandwiched between the support plate 19 and the partition plate 28. These are superimposed in order. The mutual contact surfaces are formed on a smooth plane orthogonal to the axis of the drive shaft 18. The contact surfaces can be in airtight contact with each other. Similarly, the second intermediate member 29 is sandwiched between the partition plate 28 and the lower member 31. These are superimposed in order. The mutual contact surfaces are formed on a smooth plane orthogonal to the axis of the drive shaft 18. The contact surfaces can be in airtight contact with each other. The hollow space of the first intermediate member 27 forms a first piston chamber 32. The hollow space of the second intermediate member 29 forms a second piston chamber 33.

  A suction port 34 is formed in the first intermediate member 27. The suction port 34 opens into the first piston chamber 32. A suction pipe 14 a is connected to the suction port 34. Thus, gas can be introduced into the piston chamber 32 from the suction pipe 14a. Similarly, a suction port 35 is formed in the second intermediate member 29. The suction port 35 opens into the second piston chamber 33. A suction pipe 14 b is connected to the suction port 35. Thus, gas can be introduced into the piston chamber 33 from the suction pipe 14b.

  A discharge port 36 is formed in the support plate 19. The discharge port 36 opens into the first piston chamber 32. A first discharge chamber 37 is formed outside the support plate 19. The discharge port 36 is connected to the first discharge chamber 37. A discharge port 38 is formed in the lower member 31. The discharge port 38 opens into the second piston chamber 33. A second discharge chamber 39 is formed outside the lower member 31. The discharge port 37 is connected to the second discharge chamber 39. The second discharge chamber 39 is connected to the first discharge chamber 37. A through path may be formed in the support plate 19, the first intermediate member 27, the partition plate 28, the second intermediate member 29, and the lower member 31 for connection. The first discharge chamber 37 opens into the sealed space 13 in the housing 12. Thus, the first discharge chamber 37 and the second discharge chamber 39 are connected to the discharge pipe 15.

  The compression unit 17 includes a first piston 41. The first piston 41 is accommodated in the first piston chamber 32. The first piston 41 is fixed to the drive shaft 18. The first piston 41 is slidably sandwiched between the support plate 19 and the partition plate 28. The first piston 41 is formed in an annular shape surrounding the drive shaft 18 without interruption around the axis of the drive shaft 18. The upper surface and the lower surface of the first piston 41 are partitioned by a pair of mutually parallel planes. The upper surface and the lower surface are orthogonal to the axis of the drive shaft 18. The first piston 41 is hermetically in contact with the downward surface of the support plate 19 on the upper surface around the axis of the drive shaft 18 and hermetically in contact with the upward surface of the partition plate 28 on the lower surface.

  The compression unit 17 includes a second piston 42. The second piston 42 is accommodated in the second piston chamber 33. The second piston 42 is fixed to the drive shaft 18. The second piston 42 is slidably sandwiched between the partition plate 28 and the lower member 31. The second piston 42 is formed in an annular shape surrounding the drive shaft 18 without interruption around the axis of the drive shaft 18. The upper surface and the lower surface of the second piston 42 are partitioned by a pair of mutually parallel planes. The upper surface and the lower surface are orthogonal to the axis of the drive shaft 18. The second piston 42 is hermetically in contact with the downward surface of the partition plate 28 on the upper surface around the axis of the drive shaft 18 and hermetically in contact with the upward surface of the lower member 31 on the lower surface.

  As shown in FIG. 2, the second piston chamber 33 is partitioned by a cylindrical surface coaxial with the drive shaft 18. The second piston 42 is eccentric from the axis of the drive shaft 18 and is fixed to the drive shaft 18. The second piston 42 is in contact with the inner wall surface of the second piston chamber 33 at one bus bar farthest from the axis of the drive shaft 18. When the drive shaft 18 rotates about the axis, the second piston 42 can continue to contact the inner wall surface of the second piston chamber 33 at the bus. A compression chamber is defined between the inner wall surface of the second piston chamber 33 and the outer wall of the second piston 42.

  A blade plate 43 is incorporated in the second intermediate member 29 in the second piston chamber 33. The vane plate 43 extends along a plane including the axis of the drive shaft 18. The blade plate 43 is inserted into the blade groove 44 so as to be movable forward and backward with respect to the axis of the drive shaft 18 in parallel to a plane including the axis of the drive shaft 18. The vane plate 43 has a contact edge 43 a extending linearly between the partition plate 28 and the lower member 31. The vane plate 43 contacts the outer wall of the second piston 42 at the contact edge 43a. A pressing force is applied to the blade plate 43 toward the second piston 42. As a result, regardless of the eccentricity of the second piston 42, the contact edge 43 a of the blade plate 43 can continue to contact the outer wall of the second piston 42 when the second piston 42 rotates. The first piston 41 is accommodated in the first piston chamber 32 in the same manner as the second piston 42.

  The compression chamber is divided into two parts by the action of the blades 43. An expansion chamber 46 is defined between the inner wall surface of the second piston chamber 33 and the second piston 42 on the downstream side of the blade plate 43 in the rotation direction of the second piston 42. A suction port 35 is opened in the expansion chamber 46. The suction port 35 is arranged as close to the blade plate 43 as possible. A reduction chamber 47 is defined between the inner wall surface of the second piston chamber 33 and the second piston 42 on the upstream side of the blade plate 43 in the rotation direction of the second piston 42. A discharge port 38 opens in the reduction chamber 47. The discharge port 38 is disposed as close to the blade plate 43 as possible. When the suction port 35 is closed according to the rotation of the second piston 42, the reduction chamber 47 expands to the maximum extent. Thereafter, the reduction chamber 47 is reduced. As a result, the gas in the reduction chamber 47 is compressed. The compressed gas is discharged from the discharge port 38. While the reduction chamber 47 is being reduced, the expansion chamber 46 is enlarged in parallel. Gas is introduced into the expansion chamber 46 from the suction port 35. In this way, gas introduction and compression are realized for each rotation of the second piston 42. Similarly, introduction and compression of gas are realized for each rotation of the first piston 41. However, a phase difference of 180 degrees is set between the compression stroke of the first piston 41 and the compression stroke of the second piston 42 by the rotation angle of the drive shaft 18.

  FIG. 3 schematically shows a control system of the electric motor. The electric motor 16 according to the present embodiment is a four-pole electric motor. A power module 51 is connected to the electric motor 16. The power supply module 51 includes a power supply circuit 52 and an inverter circuit 53. The power supply circuit 52 includes an AC / DC conversion circuit 54. The AC / DC conversion circuit 54 is connected to an AC power supply 55. The AC / DC conversion circuit 54 performs full-wave rectification on the AC voltage. As a result, the AC / DC conversion circuit 54 outputs a DC voltage.

  The inverter circuit 53 includes three groups of switching elements 56a and 56b corresponding to the U phase, the V phase, and the W phase. The switching elements 56a and 56b are connected in series for each group. A field effect transistor (for example, MOSFET) can be used for the switching elements 56a and 56b. The positive terminal of the AC / DC conversion circuit 54 is connected to the source of the upstream switching element 56a. The source of the downstream switching element 56b is connected to the drain of the upstream switching element 56a. The winding of the magnetic pole 25 of the stator 23 is connected to the drain of the upstream switching element 56a and the source of the downstream switching element 56b for each group. The negative terminal of the AC / DC conversion circuit 54 is connected to the drain of the downstream switching element 56b.

  A control circuit 57 is connected to the gates of the switching elements 56a and 56b. The control circuit 57 supplies a control signal to the gates of the switching elements 56a and 56b. In supplying the control signal, the control circuit 57 executes PWM (pulse width modulation) control. A control voltage is supplied to the gate of either the upstream switching element 56a or the downstream switching element 56b for each group. When the control voltage is supplied, the output of the AC / DC conversion circuit 54 is supplied to the winding of the magnetic pole 25 for each of the U phase, the V phase, and the W phase. As will be described later, as a result of the switching elements 56a and 56b being repeatedly turned on and off in a prescribed pattern, the rotor 22 rotates with respect to the stator 23. Thus, the electric motor 16 operates.

  A zero-cross detection circuit (first detection circuit) 58 and a position detection circuit (second detection circuit) 59 are connected to the control circuit 57. In generating the control signal, the control circuit 57 refers to the outputs of the zero cross detection circuit 58 and the position detection circuit 59. The zero-cross detection circuit 58 and the position detection circuit 59 can be connected to the first port 57a and the second port 57b of the control circuit 57, respectively. The first port 57a and the second port 57b can be provided, for example, as one terminal of a microprocessor chip constituting the control circuit 57.

  The zero cross detection circuit 58 is connected to the AC / DC conversion circuit 54. The zero cross detection circuit 58 detects the zero point of the input voltage of the AC / DC conversion circuit 54. Since the AC / DC conversion circuit rectifies the alternating current, the output voltage fluctuates at a constant period (1/2 times the power supply voltage period). The interval between zero points corresponds to the cycle of fluctuation. Therefore, if the zero point of the output voltage is detected, the phase of the output voltage can be specified. The zero cross detection circuit 58 outputs a zero cross signal (first signal). The phase of the output voltage of the AC / DC conversion circuit 54 is specified by the zero cross signal.

  The position detection circuit 59 detects the position of the rotor 22 with respect to the stator 23. In detection, the induced voltages of the U phase, the V phase, and the W phase are monitored. The induced voltage is compared to a reference voltage. The electric motor 16 is configured in a so-called sensorless manner. Detection points are set on the rotor 22. The passage of detection points is monitored at fixed points with uniform angular intervals. The position detection circuit 59 outputs a rotor position signal (second signal) each time it passes. That is, the position of the rotor 22 is specified by the position signal. The load torque of the electric motor 16 fluctuates within one rotation of the rotor 22, and the fluctuation is repeated every rotation. Therefore, the variation in load torque can be related to the position of the rotor 22. Thus, the phase of the load torque of the rotor 22 can be specified by the position signal. Here, as shown in FIG. 4, the load torque of the electric motor 16 fluctuates at a period of ½ rotation of the rotor 22 by the action of the two pistons 41 and 42.

  Next, the operation of the control circuit 57 will be described. The control circuit 57 includes an arithmetic circuit. The arithmetic circuit can realize an operation based on a predetermined software program. In addition, the control circuit 57 can be configured by hardware having functional blocks corresponding to individual operations. As shown in FIG. 5, the control circuit 57 controls the rotation speed of the electric motor 16. In step S1, the compressor 11 is started up. In step S <b> 2, the control circuit 57 acquires a position signal from the position detection circuit 59. When the position signal is acquired, the control circuit 57 switches the phase of the electric motor 16 in step S3. The switching elements 56a and 56b are switched. The position detection signal is a trigger for switching the switching elements 56a and 56b.

  In step S4, the control circuit 57 calculates the time interval based on the time of the current position signal and the time of the previous position signal. This time interval corresponds to the time length of the phase of the electric motor 16. As the rotational speed increases, the time length of the phase is reduced. As the rotational speed decreases, the time length of the phase increases.

  In step S5, the control circuit 57 calculates the rotational speed of the rotor 22, that is, the actual rotational speed, based on the time length. Here, since each phase is fixed in an angle range of 12 divisions, the rotation speed can be easily calculated from the time interval. In step S6, the control circuit 57 compares the actual rotational speed with the designated rotational speed. If the actual rotational speed is lower than the designated rotational speed, the control circuit 57 increases the pulse width of the PWM control to increase the output voltage of the inverter circuit 53 in step S7. As a result, an increase in the actual rotational speed is expected. The processing operation of the control circuit 57 returns to step S2. The control circuit 57 waits until the next position signal is input. If the actual rotational speed exceeds the instruction rotational speed in step S8, the control circuit 57 reduces the pulse width of the PWM control and decreases the output voltage of the inverter circuit 53 in step S9. As a result, the actual rotational speed is expected to decrease. The processing operation of the control circuit 57 returns to step S2. If the actual rotational speed matches the instruction rotational speed, the processing operation of the control circuit 57 returns from step S8 to step S2. Thus, the rotation of the rotor 22 is maintained at the indicated rotational speed.

  On the other hand, the control circuit 57 controls the phase of the load torque as a result by controlling the rotational speed of the rotor 22 as shown in FIG. The phase of the load torque corresponds to the position signal. In this control, the specific position of the rotor 22 is adjusted to the zero cross of the output voltage. In step T1, the control circuit 57 acquires a zero cross signal. When the zero cross signal is acquired, the control circuit 57 specifies the phase of the electric motor 16 at the time of acquiring the zero cross signal in step T2. The identified phase is remembered. As described above, since the variation of the load torque is related to the position of the rotor 22, the phase of the load torque can be stored according to the storage of the phase.

  In step T3, the control circuit 57 calculates the time interval between the time of the current zero cross signal and the time of the previous zero cross signal. This time interval corresponds to the period of the output voltage. The cycle of this output voltage is twice the voltage frequency of the AC power supply 55. Therefore, if the voltage frequency of the AC power supply 55 decreases, the cycle of the output voltage is extended.

  In step T4, the control circuit 57 calculates the power supply frequency based on the period of the output voltage. In step T5, the control circuit 57 sets an instruction rotational speed for rotational control. A rotation speed corresponding to the power supply frequency (voltage frequency of the AC power supply 55) is set as the instruction rotation speed. Therefore, the fluctuation of the output voltage and the fluctuation of the load torque are synchronized.

  In step T6, the control circuit 57 compares the actual rotational speed with the designated rotational speed. If the actual rotational speed matches the indicated rotational speed, the control circuit 57 detects a phase shift between the output voltage and the rotational synchronization of the rotor 22 at step T7. The control circuit 57 determines that synchronization is maintained between the output voltage and the load torque. If the actual rotational speed deviates from the designated rotational speed, the control circuit 57 ends the phase control. The control circuit 57 determines that synchronization is not ensured between the output voltage and the load torque. The processing operation of the control circuit 57 returns to step T1. The control circuit 57 waits until the next zero cross signal is input.

  In detecting the phase shift, the control circuit 57 calls the position of the rotor 22 stored in step T2. If the phase of the rotor 22 matches the desired phase, the processing operation of the control circuit 57 returns to step T1. No phase shift is confirmed. The control circuit 57 waits until the next zero cross signal is input. When the phase shift is confirmed in step T7, the control circuit 57 resets the designated rotational speed in step T8. The control circuit 57 increases or decreases the indicated rotational speed from the rotational speed corresponding to the power supply frequency by a minute rotational speed β.

  When the command rotational speed is reset at step T8, the control circuit 57 monitors the elimination of the phase shift at step T9. If the phase shift is eliminated, the control circuit 57 resets the indicated rotational speed in step T10. The command rotational speed is returned to the rotational speed corresponding to the power supply frequency. As a result, synchronization is again ensured between the output voltage and the rotation of the rotor 22. Phase matching is maintained.

  If the phase shift is not eliminated in step T9, the control circuit 57 stands by until the next zero cross signal is inputted in step T11. When the zero-cross signal is acquired, the control circuit 57 specifies the phase of the electric motor 16 in step T12. The identified phase is remembered. The processes in steps T9, T11, and T12 are repeated until the phase shift is eliminated in this way. As a result, the phase matches between the output voltage and the load torque.

  As shown in FIG. 7, in the power supply module 51, the switching elements 56a and 56b are turned on and off. For example, when a control signal is supplied to the switching element 56 a (U) and the switching element 56 b (Y), the UY phase is established in the electric motor 16. In the half rotation of the rotor 22, “UY phase”, “UZ phase”, “VZ phase”, “VX phase”, “WX phase”, and “WY phase” are established in order. In this way, the “phase” is switched according to the combination of the switching elements 56a and 56b. Here, since the first piston 41 and the second piston 42 are fixed to the drive shaft 18, the load fluctuation of the compressor 11 is related to the phase of the electric motor 16. Here, the “UY phase” of the electric motor 16 corresponds to the lightest load phase of the compressor 11.

  As shown in FIG. 7, since no smoothing capacitor is connected to the AC / DC conversion circuit 54, the output voltage of the AC / DC conversion circuit 54 fluctuates in a cycle that is a half of the cycle T of the AC voltage. When the duty ratio of the PWM control is maintained at 100%, the output voltage of the inverter circuit 53 varies in a cycle of T / 2. At this time, if the lightest load phase of the load of the compressor 11 and the time point of zero crossing of the output voltage are matched, the fluctuation of the output voltage and the fluctuation of the load torque can be synchronized. The periodic variation of the output voltage is combined with the periodic variation of the load torque. As a result, adjustment of the output voltage can be omitted. Since the output voltage reflects the fluctuation of the load torque, the uneven rotation of the electric motor 16 can be suppressed regardless of the fluctuation of the load torque. Since the periodic fluctuation of the output voltage is used to eliminate the rotation unevenness, the output voltage can be used to the maximum without being discarded. A decrease in the voltage utilization factor can be prevented. Here, the lightest load phase corresponds to the rotational position of the lowest load torque.

  As described above, the load torque of the electric motor 16 varies within one rotation of the rotor 22 (see FIG. 4), and the variation is repeated every rotation. Such fluctuations in load torque can be specified in advance. As described above, if the zero crossing of the output voltage is adjusted to the rotational position of the minimum load torque, the periodic fluctuation of the output voltage and the periodic fluctuation of the load torque can be synchronized. The increase / decrease timing matches. As a result, the rotational unevenness can be prevented to the maximum.

  In the present embodiment, the instruction rotational speed is intentionally shifted from the rotational speed corresponding to the power supply frequency in controlling the phase. When the rotational speed deviates in this way, the phase of rotation of the electric motor 16 deviates from the phase of the output voltage. When the rotation speed is returned to the rotation speed that matches the output voltage at the time when the rotation phase matches the phase of the output voltage, the rotation of the motor 16 keeps the phase of the output voltage at the output voltage period. Can be synchronized. The phase shift between the output voltage and the load torque can be eliminated.

  FIG. 8 schematically shows the configuration of the air conditioner. The air conditioner 101 includes a compressor 11. The compressor 11 is incorporated in the first circulation path 102. The first circulation path 102 connects the first port 103a and the second port 103b of the four-way valve 103 to each other. The first and second suction pipes 14a and 14b of the compressor 11 are connected to the first port 103a of the four-way valve 103 via a refrigerant pipe. The gas refrigerant is supplied from the first port 103a to the first and second suction pipes 14a and 14b of the compressor 11. The compressor 11 compresses the low-pressure gas refrigerant to a predetermined pressure. The discharge pipe 15 of the compressor 11 is connected to the second port 103b of the four-way valve 103 via a refrigerant pipe. Gas refrigerant is supplied from the discharge pipe 15 of the compressor 11 to the second port 103 b of the four-way valve 103. The first circulation path 102 is formed by a refrigerant pipe such as a copper pipe.

  Refrigerant piping that forms the second circulation path 104 is connected to the third port 103 c and the fourth port 103 d of the four-way valve 103. The second circulation path 104 connects the third port 103c and the fourth port 103d of the four-way valve 103 to each other. An outdoor heat exchanger 105, an expansion valve 106, and an indoor heat exchanger 107 are incorporated into the second circulation path 104 in order from the third port 103c side. The outdoor heat exchanger 105 realizes heat energy exchange between the refrigerant passing therethrough and ambient air. The indoor heat exchanger 107 realizes heat energy exchange between the refrigerant passing therethrough and ambient air. The second circulation path 1104 may be formed by a refrigerant pipe such as a copper pipe.

  A blower fan 108 is installed in association with the outdoor heat exchanger 105. The blower fan 108 generates an air flow according to the rotation of the impeller. The airflow passes through the outdoor heat exchanger 105. The flow rate of the passing air flow is adjusted according to the number of revolutions per minute of the impeller. In the outdoor heat exchanger 105, the amount of heat energy exchanged between the refrigerant and the air is adjusted according to the flow rate of the airflow.

  A blower fan 109 is installed in association with the indoor heat exchanger 107. The blower fan 109 generates an air flow according to the rotation of the impeller. The airflow passes through the indoor heat exchanger 107. The flow rate of the passing air flow is adjusted according to the number of revolutions per minute of the impeller. In the indoor heat exchanger 107, the amount of heat energy exchanged between the refrigerant and the air can be adjusted according to the flow rate of the airflow. The indoor heat exchanger 107 and the blower fan 109 are incorporated in, for example, an indoor unit. The indoor unit is installed in an indoor space RM in a building, for example. In addition, the indoor unit may be installed in an environmental space corresponding to the indoor space RM.

  When the cooling operation is set, the four-way valve 103 connects the second port 103b and the third port 103c to each other and connects the first port 103a and the fourth port 103d to each other. Therefore, high-temperature and high-pressure refrigerant is supplied from the compressor 11 to the outdoor heat exchanger 105. The refrigerant flows through the outdoor heat exchanger 105, the expansion valve 106, and the indoor heat exchanger 107 in order. In the outdoor heat exchanger 105, the heat energy of the refrigerant is released to the outside air. The refrigerant is decompressed to a low pressure by the expansion valve 106. The decompressed refrigerant absorbs heat from ambient air in the indoor heat exchanger 107. Cold air is generated. The cold air is caused to flow into the indoor space RM by the function of the blower fan 109.

  When the heating operation is set, the four-way valve 103 connects the second port 103b and the fourth port 104d to each other and connects the first port 103a and the third port 103c to each other. A high-temperature and high-pressure refrigerant is supplied from the compressor 11 to the indoor heat exchanger 107. The refrigerant flows through the indoor heat exchanger 107, the expansion valve 106, and the outdoor heat exchanger 105 in order. In the indoor heat exchanger 107, the heat energy of the refrigerant is released to the surrounding air. Warm air is generated. The warm air is caused to flow into the indoor space RM by the function of the blower fan 109. The refrigerant is decompressed to a low pressure by the expansion valve 106. The decompressed refrigerant absorbs heat from the surrounding air in the outdoor heat exchanger 105. Thereafter, the refrigerant is returned to the compressor 11.

  In addition, the compressor 11 can be used in a refrigerator, a freezer, a refrigerated product case, a frozen product case, an in-vehicle air conditioner, and other devices. In addition to the rotary piston as described above, a reciprocating piston or a scroll piston can be used for the compressor 11.

  DESCRIPTION OF SYMBOLS 11 Compressor, 16 Electric motor, 54 AC / DC conversion circuit, 57 Control circuit, 57a 1st port, 57b 2nd port, 58 1st detection circuit (zero cross detection circuit), 59 2nd detection circuit (position detection circuit)

Claims (7)

Identifying the phase of the output voltage of the AC / DC conversion circuit that varies periodically;
Identifying the phase of rotation of the motor;
And a step of controlling the number of rotations of the motor to adjust the phase of the rotation to the phase of the output voltage.   The method for controlling an electric motor according to claim 1, further comprising: a step of specifying a zero cross of the output voltage in matching the phase; and a step of comparing the time of the zero cross with the rotation of the electric motor. To control the motor.   2. The method for controlling an electric motor according to claim 1, wherein a step of maintaining synchronization between the output voltage and the rotation and a phase shift between the output voltage and the rotation are detected while the synchronization is maintained. And a step of increasing / decreasing the number of revolutions of the motor from the number of revolutions coincident with the cycle of the output voltage. A first port that receives a first signal that specifies a phase of an output voltage of an AC / DC conversion circuit that varies periodically;
A second port for receiving a second signal specifying the phase of rotation of the electric motor;
An electric motor control circuit, comprising: an arithmetic circuit connected to the first port and the second port to control the rotation speed of the electric motor and adjust the phase of the rotation to the phase of the output voltage. A first detection circuit for detecting a phase of the output voltage of the AC / DC conversion circuit that varies periodically;
A second detection circuit for detecting the phase of the rotor;
And an arithmetic circuit connected to the first detection circuit and the second detection circuit, for controlling the number of rotations of the rotor to adjust the phase of the rotor to the phase of the output voltage. Motor with module.   6. A compressor comprising: the electric motor with a power module according to claim 5; and a piston connected to the electric motor with the power module and defining a compression chamber in a piston chamber.   An air conditioner comprising the compressor according to claim 6.

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