JP2017022877A - Control device for two-phase induction motor and heat pump device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a two-phase induction motor so as to reduce a peak value of a motor current at the time of start-up, while preventing a motor voltage from being limited as much as possible.SOLUTION: In a control device 10 of a two-phase induction motor 2, a first driving circuit 30 applies a single-phase AC voltage supplied from a switching circuit 20 to a first winding 4, and applies it to a second winding 5 via a capacitor 31. A second driving circuit 60 includes a converter 40 for converting the single-phase AC voltage supplied from the switching circuit 20 into a DC voltage, and an inverter 50 for converting the output DC voltage of the converter 40 into a two-phase AC voltage and applying the same to the first and second windings 4 and 5. By switching control of the switching circuit 20, when an effective value of the single-phase AC voltage is equal to or less than a threshold value, a control unit 61 starts and operates the two-phase induction motor 2 using the first driving circuit 30. When the effective value of the single-phase AC voltage exceeds the threshold value, the control unit 61 starts and operates the two-phase induction motor 2 using the second driving circuit 60.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for a two-phase induction motor and a heat pump device including a compressor driven by the two-phase induction motor, and is suitably used in, for example, an air conditioner.

  The two-phase induction motor generates a rotating magnetic field by two-phase stator windings (main winding and auxiliary winding), and drives the rotor by this rotating magnetic field. Normally, a system (running capacitor system) is used in which a phase difference of 90 ° is generated between the current flowing through the main winding and the current flowing through the auxiliary winding by connecting a capacitor to the auxiliary winding. On the other hand, an inverter drive system is also used in which a two-phase alternating current generated by an inverter circuit is supplied to the main winding and the auxiliary winding without providing a running capacitor. Furthermore, a method of driving a two-phase induction motor by switching between the running capacitor method and the inverter driving method has been proposed.

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-101518) discloses an operation control method in which a two-phase induction motor is normally driven by an inverter drive method and a two-phase induction motor is driven by a running capacitor method when the inverter fails. Is disclosed.

  The control circuit disclosed in Patent Document 2 (Japanese Utility Model Publication No. 63-55798) is configured such that a running capacitor type induction motor can be driven by each of a commercial power source and an inverter power source. 1 is different in configuration. Specifically, in the case of this document, the connection of a plurality of capacitors connected to the auxiliary winding can be switched, and these capacitors are connected in parallel when operated with a commercial power supply, and are connected in series when operated with an inverter power supply. Is done.

JP 2010-101518 A Japanese Utility Model Publication No. 63-55798

  The inventor of the present application has found the following problems that have not been fully recognized until now as a result of a comparative study between a running capacitor type two-phase induction motor and an inverter drive type two-phase induction motor. It was. That is, the running capacitor type two-phase induction motor is low in cost because of its simple circuit configuration, but has a problem that a very large motor current flows when the motor is started. When the input AC power supply voltage is large, the power supply breaker may be activated. On the other hand, in the case of the inverter drive system, the motor current at start-up can be greatly reduced, but the voltage applied to the stator winding is insufficient due to the limitation of the inverter conversion efficiency, resulting in the motor rotation speed. There is a problem that cannot be raised sufficiently.

  The present invention has been made in consideration of the above-mentioned problems, and its main object is to suppress the peak value of the motor current at the start and to limit the motor voltage as much as possible in the control device for the two-phase induction motor. Is to do so.

  In one aspect, the present invention is a control device for a two-phase induction motor. The two-phase induction motor includes a first winding and a second winding for generating a rotating magnetic field. The control device includes a switching circuit, a first drive circuit, a second drive circuit, and a control unit. The switching circuit switches the supply destination of the single-phase AC voltage. The first drive circuit applies the single-phase AC voltage supplied from the switching circuit to the first winding and to the second winding via the capacitor. The second drive circuit includes a converter and an inverter. The converter converts the single-phase AC voltage supplied from the switching circuit into a DC voltage. The inverter converts the output DC voltage of the converter into a two-phase AC voltage, and applies the converted two-phase AC voltage to the first and second windings. The control unit performs switching control of the switching circuit to start and operate the two-phase induction motor using the first driving circuit when the effective value or amplitude of the single-phase AC voltage is equal to or less than the threshold. When the effective value or amplitude of the phase AC voltage exceeds the threshold value, the two-phase induction motor is started and operated using the second drive circuit.

  When the two-phase induction motor is driven by the first drive circuit, as the effective value or amplitude of the single-phase AC voltage increases, the current peak values of the first and second windings at the start of the two-phase induction motor are To increase. In this case, preferably, the threshold value is set equal to the first reference value when the effective value or amplitude of the single-phase AC voltage when the current peak value at start-up reaches the upper limit value is the first reference value. .

  When the two-phase induction motor is driven by the second drive circuit, the maximum rotation speed of the two-phase induction motor increases as the effective value or amplitude of the single-phase AC voltage increases. In this case, preferably, the maximum rotation speed of the two-phase induction motor when driven by the second drive circuit reaches the rotation speed of the two-phase induction motor when driven by the first drive circuit. Assuming that the effective value or amplitude of the single-phase AC voltage is the second reference value, when the first reference value is less than the second reference value, the threshold is set equal to the first reference value, and the first reference value Is equal to or greater than the second reference value, the threshold is set equal to the second reference value.

  In another aspect, the present invention is a heat pump device. The heat pump device compresses and compresses the condenser that condenses the refrigerant, the expansion valve that expands the refrigerant that has passed through the condenser, the evaporator that evaporates the refrigerant that has passed through the expansion valve, and the refrigerant that has passed through the evaporator A compressor that discharges the refrigerant to the condenser. The compressor includes a two-phase induction motor that drives the compression mechanism and the above-described control device that controls the two-phase induction motor.

  Preferably, the control unit sets the threshold based on the temperature of the condenser immediately before starting the operation of the compressor or the ambient temperature of the condenser.

  According to the present invention, it is possible to control the two-phase induction motor so as to suppress the peak value of the motor current at start-up and to limit the motor voltage as much as possible.

It is a block diagram which shows the structure of the control apparatus of the two-phase induction motor by 1st Embodiment. It is a figure which shows an example of the waveform of the motor voltage and motor current of a two-phase induction motor. It is a flowchart which shows the operation control procedure of the two-phase induction motor by 1st Embodiment. It is a figure which shows roughly the relationship between the effective value of an input power supply voltage, the maximum rotational speed of a two-phase induction motor, and the peak value of the motor current at the time of starting. FIG. 5 is a diagram showing the characteristics of a two-phase induction motor when voltage VB1 is set as a threshold value when the load torque is large in FIG. FIG. 5 is a diagram showing the characteristics of a two-phase induction motor when voltage VB2 is set as a threshold value when load torque is small in FIG. It is a flowchart which shows an example of the setting method of the threshold value used by step S110 of FIG. It is a flowchart which shows the modification of the setting method of the threshold value used by step S110 of FIG. It is a figure which shows typically the refrigerant circuit of an air conditioner. It is a figure which shows typically the relationship between the load torque at the time of starting of a two-phase induction motor, and a condenser temperature. It is a figure which shows typically an example of the relationship between the threshold value used by step S110 of FIG. 3, and the condenser temperature at the time of a compressor stop. It is a figure which shows typically the other example of the relationship between the threshold value used by step S110 of FIG. 3, and the condenser temperature at the time of a compressor stop. It is a flowchart which shows the operation control procedure of the two-phase induction motor used with the compressor of an air conditioner.

  Hereinafter, embodiments will be described in detail with reference to the drawings. The same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

<First Embodiment>
[Configuration of control device for two-phase induction motor]
FIG. 1 is a block diagram showing a configuration of a control device for a two-phase induction motor according to the first embodiment. Referring to FIG. 1, a control device 10 that drives and controls the two-phase induction motor 2 includes a switching circuit 20, a first drive circuit 30, a second drive circuit 60, and AC voltage detectors 70, 73, 74, AC current detectors 71 and 72, and a control unit 61.

  The two-phase induction motor 2 includes a rotor 3 and a main winding 4 and an auxiliary winding 5 as stator windings. As the rotor 3, for example, a cage rotor can be used. In FIG. 1, the voltage applied to the main winding 4 is Vmain, and the current flowing through the main winding 4 is Imain. The voltage applied to the auxiliary winding 5 is Vaux, and the current flowing through the auxiliary winding 5 is Iaux. A rotating magnetic field is formed by making the phase of the current Imain flowing in the main winding 4 different from the phase of the current Iaux flowing in the auxiliary winding 5, and the rotor 3 is driven to rotate by this rotating magnetic field.

  In the control device 10, the switching circuit 20 is configured to supply a single-phase AC voltage from the single-phase AC power supply 1 to the first drive circuit 30 and a second drive circuit based on the control signal SW <b> 1 from the control unit 61. It can be switched to either the case of supplying to 60.

  Specifically, in the example of FIG. 1, the switching circuit 20 includes changeover switches 21 and 24. The changeover switch 21 includes an input terminal 22 and output terminals 23a and 23b, and the changeover switch 24 includes an input terminal 25 and output terminals 26a and 26b. The single-phase AC power source 1 is connected between the input terminal 22 of the changeover switch 21 and the input terminal 25 of the changeover switch 24. By switching the changeover switches 21 and 24 to the first output terminals 23 a and 26 a, the voltage from the single-phase AC power supply 1 is supplied to the first drive circuit 30. Conversely, the voltage from the single-phase AC power supply 1 is supplied to the second drive circuit 60 by switching the changeover switches 21 and 24 to the second output terminals 23b and 26b, respectively.

  The first drive circuit 30 drives the two-phase induction motor 2 by a running capacitor method based on the single-phase AC voltage supplied via the switching circuit 20. The drive circuit 30 includes a capacitor 31 and an open / close circuit 32.

  The capacitor 31 is provided to delay the phase of the current Iaux flowing through the auxiliary winding 5 by 90 ° with respect to the phase of the current Imain flowing through the main winding 4. Specifically, the first output terminal 23a of the changeover switch 21 is connected to one end (node N1) of the main winding 4 and to one end (node N2) of the auxiliary winding 5 via the capacitor 31. Connected. The first output terminal 26a of the changeover switch 24 is connected to the other end of the main winding 4 and the other end of the auxiliary winding 5 (the common node N3 of both).

  The open / close circuit 32 is connected between the open / close switch 33 connected between one end of the capacitor 31 and the node N1 of the two-phase induction motor 2, and between the other end of the capacitor 31 and the node N2 of the two-phase induction motor 2. Open / close switch 34. The open / close switches 33 and 34 are switched on or off based on a control signal SW2 from the controller 61. Specifically, when the voltage from the single-phase AC power supply 1 is supplied to the first drive circuit 30 via the switching circuit 20, the open / close switches 33 and 34 are set to the on state. Conversely, when the voltage from the single-phase AC power supply 1 is supplied to the second drive circuit 60, the open / close switches 33 and 34 are set to the off state. As a result, the capacitor 31 is disconnected from the two-phase induction motor 2.

  The second drive circuit 60 drives the two-phase induction motor 2 by an inverter drive system based on the single-phase AC voltage supplied via the switching circuit 20. The second drive circuit 60 converts the single-phase AC voltage supplied via the switching circuit 20 into a DC voltage, and converts the output DC voltage of the converter 40 into a two-phase AC voltage to convert the stator winding And an inverter 50 to be supplied.

  In the example of FIG. 1, the converter 40 includes a diode bridge rectifier circuit constituted by diodes 41, 42, 43, 44 and a smoothing capacitor 45. Instead of the smoothing capacitor 45, a power factor correction converter may be provided.

  Inverter 50 includes six semiconductor switching elements 51 to 56 and six diodes connected to these semiconductor switching elements in parallel and in a reverse bias direction, respectively. In the case of FIG. 1, each of the semiconductor switching elements 51 to 56 is configured by an IGBT (Insulated Gate Bipolar Transistor), but may be a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or a bipolar transistor.

  Hereinafter, the connection of the semiconductor switching elements 51 to 56 will be described. Semiconductor switching elements 51 and 52 are connected in series between output node Np on the high voltage side of converter 40 and output node Nn on the low voltage side. The connection node Na of the semiconductor switching elements 51 and 52 is connected to the node N1 of the two-phase induction motor 2. Similarly, the semiconductor switching elements 53 and 54 are connected in series between the output nodes Np and Nn and in parallel with the entire semiconductor switching elements 51 and 52 connected in series. Connection node Nb of semiconductor switching elements 53 and 54 is connected to node N2 of two-phase induction motor 2. Semiconductor switching elements 55 and 56 are connected in series between output nodes Np and Nn and in parallel with the whole of semiconductor switching elements 51 and 52 connected in series and the whole of semiconductor switching elements 53 and 54 connected in series. . Connection node Nc of semiconductor switching elements 55 and 56 is connected to node N3 of two-phase induction motor 2.

  Next, the operation of the inverter 50 will be briefly described. Switching of the semiconductor switching elements 51 to 56 is controlled by control signals S1 to S6 from the control unit 61, respectively. First, the semiconductor switching elements 51 and 56 are turned on, and the other switching elements are turned off, so that the main current Imain in the positive direction flows through the main winding 4. Next, when the semiconductor switching elements 53 and 56 are turned on and the other switching elements are turned off, the auxiliary current Iaux in the positive direction flows through the auxiliary winding 5. Next, when the semiconductor switching elements 52 and 55 are turned on and the other switching elements are turned off, a main current Imain in the negative direction flows through the main winding 4. Next, when the semiconductor switching elements 54 and 55 are turned on and the other switching elements are turned off, the auxiliary current Iaux in the negative direction flows through the auxiliary winding 5. Hereinafter, a rotating magnetic field is generated by repeating the above control.

  The AC voltage detector 70 detects the input power supply voltage Vin input from the single-phase AC power supply 1. The alternating current detector 71 detects the main current Imain supplied to the main winding 4. The alternating current detector 72 detects the auxiliary current Iaux supplied to the auxiliary winding 5. The AC voltage detector 73 detects the voltage Vmain applied to the main winding 4. The AC voltage detector 74 detects the voltage Vaux applied to the auxiliary winding 5.

  The control unit 61 is configured based on a microcomputer including a CPU and a memory, and controls the operation of the entire control device 10 for the two-phase induction motor 2. For example, the control unit 61 sets the inverter 50 based on the detected input voltage Vin, the current detection value Sa and the voltage detection value Sc of the main winding 4, and the current detection value Sb and the voltage detection value Sd of the auxiliary winding 5. Control signals S1 to S6 are generated for controlling the switching of the semiconductor switching elements 51 to 56 constituting the circuit. Further, the control unit 61 generates control signals SW1 and SW2 for controlling the switching of the switching circuit 20 and the opening / closing of the switching circuit 32 based on the effective value or amplitude of the input power supply voltage Vin. Details of the control method of the switching circuit 20 will be described later with reference to FIGS.

[Problems of running capacitor method and inverter drive method]
Hereinafter, each problem when driving a two-phase induction motor by a running capacitor method and when driving a two-phase induction motor by an inverter drive method will be described.

  FIG. 2 is a diagram showing an example of motor voltage and motor current waveforms of a two-phase induction motor. FIG. 2A shows an example of waveforms of motor voltage and motor current when the two-phase induction motor is started and operated by the running capacitor method. FIG. 2B shows an example of waveforms of motor voltage and motor current when the two-phase induction motor is started and operated by the inverter driving method. 2A and 2B, the effective value of the input AC voltage is assumed to be 200V.

  Referring to FIG. 2A, the two-phase induction motor is started when the time on the horizontal axis is 200 milliseconds. In the case of the running capacitor method, an AC voltage having an effective value of 200 V is suddenly applied to the main winding 4 and the auxiliary winding 5 of the two-phase induction motor at the time of starting, so excessive motor current is started. There is a problem that it sometimes flows. In the case of FIG. 2A, the peak value of the motor current at startup is about 38A. The peak current value at start-up increases as the effective value of the input AC voltage increases. As a result, an overcurrent breaker (not shown in FIG. 1) normally provided at the input section of the single-phase AC power supply 1 may operate.

  Referring to FIG. 2B, the two-phase induction motor is activated when the time on the horizontal axis is 0.2 seconds. In the case of the inverter drive system, it is possible to prevent a peak value from occurring in the motor current at the time of starting by limiting the amplitude and frequency of the current and voltage output from the inverter. The peak current value in FIG. 2B is reduced to 4A. However, since the conversion efficiency of the inverter is limited (particularly, the conversion efficiency of the two-phase motor is lower than that of the three-phase motor), the motor voltage is lower than that of the running capacitor system. The motor voltage in FIG. 2B is about 100V. The motor voltage in the case of the inverter drive system increases as the effective value of the input AC voltage increases.

[Operation of control unit]
Considering the above problems, the control unit 61 of the control device 10 of this embodiment performs operation control of the two-phase induction motor as follows.

  FIG. 3 is a flowchart showing the operation control procedure of the two-phase induction motor according to the first embodiment. With reference to FIG. 1 and FIG. 3, first, the control unit 61 uses the AC voltage detector 70 before starting the two-phase induction motor 2 to determine the effective value (or the input voltage Vin from the single-phase AC power source 1). (Amplitude value) is detected (step S100). As a result, when the effective value (or amplitude value) of the input voltage Vin exceeds a preset threshold value (YES in step S110), the control unit 61 connects the switching circuit 20 to the second drive. The circuit is switched to the circuit 60 side (inverter 50 side) (step S120). And the control part 61 starts and operates the two-phase induction motor 2 by the inverter 50 (step S130).

  On the other hand, when the effective value (or amplitude value) of the input voltage Vin is equal to or less than the threshold value (NO in step S110), the control unit 61 connects the switching circuit 20 to the first drive circuit 30 side (running capacitor circuit). (Step S140). And the control part 61 starts and operates the two-phase induction motor 2 by the 1st drive circuit 30 (running capacitor circuit) (step S150).

  By the above control, it is possible to suppress the peak value of the motor current at the start-up and to limit the motor voltage as much as possible. Hereinafter, a method for determining the threshold value will be described. In the following description, the case where the connection of the switching circuit 20 is switched to the first drive circuit 30 side and the two-phase induction motor 2 is started to operate is referred to as a first operation mode, and the connection of the switching circuit 20 is the first. A case in which the two-phase induction motor 2 is started and operated by switching to the second drive circuit 60 side is referred to as a second operation mode.

[Threshold setting procedure for operation control]
FIG. 4 is a diagram schematically showing the relationship between the effective value of the input power supply voltage, the maximum rotation speed of the two-phase induction motor, and the peak value of the motor current at start-up.

  Referring to the upper graph of FIG. 4, in the case of the first operation mode (running capacitor method), the rotational speed R1 of the two-phase induction motor is a constant value determined by the frequency of the input power supply voltage Vin. In the case of the second operation mode (inverter drive method), the maximum rotation speed R2 of the two-phase induction motor 2 increases as the effective value (or amplitude value) of the power supply voltage Vin increases. Let VC be the voltage at the intersection of the characteristic curve of the rotation speed R1 in the first operation mode and the characteristic curve of the maximum rotation speed R2 in the second operation mode.

  Referring to the lower graph of FIG. 4, in the case of the second operation mode (inverter drive method), the peak value IP2 of the motor current at start-up depends on the effective value (or amplitude value) of the input power supply voltage Vin. Therefore, it can be suppressed to a relatively low value. On the other hand, in the first operation mode (running capacitor method), the peak value IP1 of the motor current at start-up increases as the effective value (or amplitude value) of the power supply voltage Vin increases. Furthermore, the peak current at startup increases as the load torque of the two-phase induction motor 2 increases.

  Here, the upper limit value of the motor current is set to BL. The upper limit value BL is determined in consideration of the rated current of the stator winding of the two-phase induction motor, the withstand voltage of the capacitor 31, and the like. Usually, the operation of the overcurrent breaker provided on the input side of the control device 10 is performed. It is set to a value slightly lower than the current. Referring to FIG. 4, the voltage when the peak value IP1 of the motor current in the running capacitor system reaches the upper limit value BL is VB (VB1 when the load torque is large and VB2 when the load torque is small). . In one embodiment, this voltage VB is set as a threshold value in the case of operation control of the above-described two-phase induction motor. In the modification, when the voltage VC is smaller than the voltage VB, the voltage VC is set as a threshold value, and when the voltage VC is equal to or higher than the voltage VB, the voltage VB is set as the threshold value. Hereinafter, it will be described in more detail with reference to the drawings.

  FIG. 5 is a diagram showing the characteristics of the two-phase induction motor when the voltage VB1 is set as a threshold value when the load torque is large in FIG. Referring to FIG. 5, when the effective value of input power supply voltage Vin in the running capacitor method is equal to voltage VB1, it is assumed that peak value IP1 of the motor current is equal to upper limit value BL of the motor current. In this case, when the effective value of the input power supply voltage Vin is equal to or lower than the voltage VB1 (= threshold), the control unit 61 activates and operates the two-phase induction motor 2 in the first operation mode (running capacitor method). . When the effective value of the input power supply voltage Vin exceeds the voltage VB1 (= threshold), the control unit 61 activates and operates the two-phase induction motor 2 in the second operation mode (inverter control method). By such operation control, the peak value of the motor current at the time of starting can be prevented from exceeding the upper limit value BL, and when the effective value of the input power supply voltage Vin is relatively large, the motor power is higher than that of the running capacitor method. The rotational speed can be increased.

  FIG. 6 is a diagram showing the characteristics of the two-phase induction motor when the voltage VB2 is set as a threshold value when the load torque is small in FIG. Referring to FIG. 6, when the effective value of input power supply voltage Vin in the running capacitor method is equal to voltage VB2, it is assumed that peak value IP1 of motor current is equal to upper limit value BL of motor current. In this case, when the effective value of the input power supply voltage Vin is equal to or lower than the voltage VB2 (= threshold), the control unit 61 activates and operates the two-phase induction motor 2 in the first operation mode (running capacitor method). be able to. When the effective value of the input power supply voltage Vin exceeds the voltage VB2 (= threshold), the control unit 61 starts and operates the two-phase induction motor 2 in the second operation mode (inverter control method). Can do.

  However, in the case of FIG. 6, as a modification, a voltage VC lower than the voltage VB2 may be set as the threshold value. At voltage VC, the maximum rotation speed R2 in the case of the inverter drive system becomes equal to the rotation speed R1 in the case of the running capacitor system, so that the maximum rotation speed of the two-phase induction motor is further increased by switching the operation mode at voltage VC. It is because it can be made.

  The threshold value setting method used in step S110 in the flowchart of FIG. 3 will be described collectively.

  FIG. 7 is a flowchart showing an example of a threshold setting method used in step S110 of FIG. A threshold value is preset according to the procedure of FIG.

  Referring to FIGS. 1 and 7, first, connection of switching circuit 20 is switched to the running capacitor circuit (first drive circuit 30) side (step S200). Next, starting the two-phase induction motor 2 in the first operation mode (running capacitor method) is repeated while gradually increasing the effective value of the input power supply voltage Vin. Then, the input power supply voltage VB when the starting peak current becomes equal to the upper limit value (a value slightly lower than the breaker operating current) is specified (step S210). This input power supply voltage VB is set as a threshold value (step S250).

  FIG. 8 is a flowchart showing a modification of the threshold setting method used in step S110 of FIG. A threshold value is preset according to the procedure of FIG.

  Referring to FIGS. 1 and 8, first, connection of switching circuit 20 is switched to the running capacitor circuit (first drive circuit 30) side (step S200). In this connection state, the two-phase induction motor 2 is repeatedly started in the first operation mode (running capacitor method) while gradually increasing the effective value of the input power supply voltage Vin. Then, the input power supply voltage VB when the starting peak current becomes equal to the upper limit value (a value slightly lower than the breaker operating current) is specified (step S210).

  Next, the connection of the switching circuit 20 is switched to the inverter (second drive circuit 60) side (step S220). In this connected state, the two-phase induction motor 2 is operated in the second operation mode (inverter drive system) while gradually increasing the effective value of the input power supply voltage Vin. Then, the input power supply voltage VC when the maximum rotation speed of the motor becomes equal to the rotation speed in the running capacitor method is detected (step S230).

  When the voltage VB is smaller than the voltage VC (YES in step S240), the voltage VB is set as a threshold value (step S250). When voltage VB is equal to or higher than voltage VC (NO in step S240), voltage VC is set as a threshold value (step S260).

[effect]
According to the above two-phase induction motor drive device, it is possible to control the two-phase induction motor so that the peak value of the motor current at the time of startup is suppressed and the motor voltage is not limited as much as possible.

<Second Embodiment>
2nd Embodiment demonstrates the case where the control apparatus of the two-phase induction motor of 1st Embodiment is applied to the compressor of heat pump equipment. Hereinafter, an air conditioner will be described as an example, but the following embodiments are applicable to heat pump devices (for example, a refrigerator, a water heater, etc.) other than the air conditioner.

[Refrigerant circuit of air conditioner]
FIG. 9 is a diagram schematically showing a refrigerant circuit of the air conditioner. Referring to FIG. 9, an air conditioner 100 includes an outdoor unit-side heat exchanger (hereinafter referred to as “outdoor heat exchanger”) 101, an expansion valve 102, and an indoor unit-side heat exchanger (hereinafter referred to as “indoor heat”). 103 ”, a four-way valve 104, and a compressor 105, which are sequentially connected in a closed loop. The compressor 105 compresses the refrigerant. The outdoor heat exchanger 101 exchanges heat between outdoor air and refrigerant. The expansion valve 102 is controlled to adjust the flow rate of the refrigerant. The indoor heat exchanger 103 exchanges heat between indoor air and refrigerant. The four-way valve 104 switches the circulation direction of the refrigerant in the cooling operation and the heating operation.

  As the motor for driving the compression mechanism of the compressor 105, the two-phase induction motor 2 described in the first embodiment is used. Further, the control device 10 described in the first embodiment is used as a control device for the two-phase induction motor.

  During the cooling operation, as indicated by the solid line arrows in FIG. 9, the compressor 105, the four-way valve 104, the outdoor heat exchanger 101, the expansion valve 102, the indoor heat exchanger 103, the four-way valve 104, and the compressor 105 are sequentially cooled. Goes around. In this case, the outdoor heat exchanger 101 functions as a condenser for condensing and liquefying the compressed high-temperature refrigerant, and the indoor heat exchanger 103 evaporates the liquefied refrigerant to reduce the refrigerant to a low temperature. It functions as an evaporator for changing to gas. During the heating operation, as indicated by the broken-line arrows in FIG. 9, the refrigerant is refrigerant in the order of the compressor 105, the four-way valve 104, the indoor heat exchanger 103, the expansion valve 102, the outdoor heat exchanger 101, the four-way valve 104, and the compressor 105. Goes around. In this case, the outdoor heat exchanger 101 functions as an evaporator, and the indoor heat exchanger 103 functions as a condenser.

  The air conditioner further includes a temperature sensor 106 for measuring the temperature of the outdoor heat exchanger 101, a temperature sensor 107 for measuring the discharge temperature, which is the refrigerant temperature at the outlet of the compressor 105, and indoor heat exchange. And a temperature sensor 108 for measuring the temperature of the vessel 103. These temperature sensors 106, 107, 108 are, for example, thermistors. Both the temperature sensor 106 for the outdoor heat exchanger 101 and the temperature sensor 108 for the indoor heat exchanger 103 are arranged between the inlet and the outlet of the heat exchanger. Therefore, in normal cases, the temperature detected when these heat exchangers function as a condenser is the refrigerant condensation temperature, and the temperature detected when they function as an evaporator is the refrigerant evaporation temperature. is there.

  Further, a temperature sensor (not shown) for measuring the outside air temperature is attached to the outdoor unit that houses the outdoor heat exchanger 101, and a temperature sensor (not shown) for measuring the indoor temperature is used for the indoor heat exchanger 103. It is attached to the indoor unit that houses it. This temperature sensor can also be constituted by a thermistor, for example.

  In the present embodiment, the heating operation and the cooling operation are described as being switchable, but the air conditioner may be capable of only one of the heating operation and the cooling operation. In that case, the functions of the outdoor heat exchanger 101 and the indoor heat exchanger 103 are fixed as a condenser or an evaporator.

[Operation control of two-phase induction motor]
In the case of the heat pump device that drives the refrigerant circuit shown in FIG. 9, the load torque of the two-phase induction motor that drives the compressor 105 varies depending on the refrigerant temperature on the output side of the compressor 105. Therefore, the threshold value used in step S110 of FIG. 3 changes according to the refrigerant temperature. Hereinafter, this point will be described in detail.

  FIG. 10 is a diagram schematically showing the relationship between the load torque and the condenser temperature when starting the two-phase induction motor. Referring to FIGS. 9 and 10, the load torque at the start of the two-phase induction motor depends on the refrigerant temperature on the output side of compressor 105 immediately before the start, that is, the temperature of the condenser. Specifically, the load torque at the start of the two-phase induction motor increases as the condenser temperature increases. When the compressor 105 is stopped, the temperature of the condenser is equal to the ambient temperature of the condenser (outside air temperature during cooling operation, indoor temperature during heating operation), so the ambient temperature of the condenser instead of the condenser temperature. May be the refrigerant temperature on the output side of the compressor.

  FIG. 11 is a diagram schematically illustrating an example of the relationship between the threshold used in step S110 of FIG. 3 and the condenser temperature when the compressor is stopped. When the threshold value is set by the method described with reference to FIG. 7, the threshold value is set to a smaller value as the temperature of the condenser increases when the compressor is stopped (immediately before starting), as shown in FIG. 11. This is because as the condenser temperature increases (that is, as the refrigerant temperature increases), the load torque at the start of the two-phase induction motor increases, so the peak value of the motor current at the start increases. .

  FIG. 12 is a diagram schematically illustrating another example of the relationship between the threshold value used in step S110 of FIG. 3 and the condenser temperature when the compressor is stopped. When the threshold value is set by the method described with reference to FIG. 8, as shown in FIG. 11, if the condenser temperature when the compressor is stopped (immediately before starting) is equal to or lower than the threshold temperature Tth, the threshold value is a constant value VC. Set to 4, 6, and 8, when the condenser temperature is relatively low, that is, when the load torque is relatively small, a threshold value is set for voltage VC in FIGS. 4 and 6. Because you can. On the contrary, when the temperature of the condenser when the compressor is stopped (immediately before starting) exceeds the threshold temperature Tth, the threshold is smaller as the temperature of the condenser when the compressor is stopped (immediately before starting) increases. Set to a value. As described with reference to FIGS. 4, 5, and 8, when the condenser temperature is relatively high, that is, when the load torque is relatively large, the peak value of the motor current at the start exceeds the upper limit value BL. This is because it is necessary to set a threshold value for the voltage VB1 in FIGS.

  FIG. 13 is a flowchart showing the operation control procedure of the two-phase induction motor used in the compressor of the air conditioner. In the following description, the control unit 61 in FIG. 1 also performs temperature detection using a temperature sensor and control of the entire air conditioner.

  Referring to FIGS. 1, 9, and 13, first, when starting the cooling operation (YES in step S <b> 10), control unit 61 sets the outside air temperature (or before starting two-phase induction motor 2). The temperature of the outdoor heat exchanger 101) is detected using a temperature sensor (step S20). The controller 61 determines a threshold based on the detected outside air temperature (or the temperature of the outdoor heat exchanger 101) (step S30). An example of the relationship between the threshold value and the outside air temperature (the temperature of the outdoor heat exchanger 101) is shown in FIG. 11 or FIG. This relationship is experimentally determined in advance and stored in the memory of the computer that constitutes the control unit 61.

  On the other hand, when the heating operation is started (NO in step S10), the control unit 61 uses the temperature sensor for the indoor temperature (or the temperature of the indoor heat exchanger 103) before starting the two-phase induction motor 2. (Step S30). The controller 61 determines a threshold based on the detected indoor temperature (or the temperature of the indoor heat exchanger 103) (step S40). An example of the relationship between the threshold and the room temperature (the temperature of the indoor heat exchanger 103) is shown in FIG. 11 or FIG. This relationship is experimentally determined in advance and stored in the memory of the computer that constitutes the control unit 61.

  Next, the control part 61 detects the effective value (or amplitude value) of the input voltage Vin from the single-phase alternating current power supply 1 using the alternating voltage detector 70 (step S100). As a result, when the effective value (or amplitude value) of the input voltage Vin exceeds the threshold set in step S30 or S50 (YES in step S110), the control unit 61 connects the switching circuit 20 to the first. 2 is switched to the drive circuit 60 side (inverter 50 side) (step S120). And the control part 61 starts and operates the two-phase induction motor 2 by the inverter 50 (step S130).

  On the other hand, when the effective value (or amplitude value) of the input voltage Vin is equal to or less than the threshold value (NO in step S110), the control unit 61 connects the switching circuit 20 to the first drive circuit 30 side (running capacitor circuit). (Step S140). And the control part 61 starts and operates the two-phase induction motor 2 by the 1st drive circuit 30 (running capacitor circuit) (step S150).

  With the above control, the two-phase induction motor for the compressor can be controlled so that the peak value of the motor current at the time of starting is suppressed and the motor voltage is not limited as much as possible.

<Third Embodiment>
When performing cooling operation or heating operation with an air conditioner, the compressor (that is, the two-phase induction motor) is stopped when the room temperature reaches the set temperature, and the absolute value of the difference between the room temperature and the set temperature is predetermined. When the value is greater than or equal to the value, the operation control of the compressor may be performed so as to start the operation of the compressor (that is, the two-phase induction motor). Even when the compressor is controlled to be turned on / off in this way, the operation mode when the compressor is started next is determined based on the condenser temperature at the time of stoppage (or the condenser ambient temperature). It is possible to switch to one of the operation modes. As a result, as in the case of the second embodiment, it is possible to control the two-phase induction motor for the compressor so that the peak value of the motor current at the time of startup is suppressed and the motor voltage is not limited as much as possible.

<Appendix>
Hereinafter, some of the inventions disclosed in the above embodiments will be listed.

  (1) A control device 10 for the two-phase induction motor 2 is provided. The two-phase induction motor 2 includes a first winding 4 and a second winding 5 for generating a rotating magnetic field. The control device 10 includes a switching circuit 20, a first drive circuit 30, a second drive circuit 60, and a control unit 61. The switching circuit 20 switches the supply destination of the single-phase AC voltage. The first drive circuit 30 applies the single-phase AC voltage supplied from the switching circuit 20 to the first winding 4 and to the second winding 5 via the capacitor 31. Second drive circuit 60 includes a converter 40 and an inverter 50. Converter 40 converts the single-phase AC voltage supplied from switching circuit 20 into a DC voltage. Inverter 50 converts the output DC voltage of converter 40 into a two-phase AC voltage, and applies the converted two-phase AC voltage to first winding 4 and second winding 5. The control unit 61 performs switching control of the switching circuit 20 to start and operate the two-phase induction motor 2 using the first drive circuit 30 when the effective value or amplitude of the single-phase AC voltage is equal to or less than the threshold value. When the effective value or amplitude of the single-phase AC voltage exceeds the threshold value, the second drive circuit 60 is used to start and operate the two-phase induction motor 2.

  (2) In the above (1), when the two-phase induction motor 2 is driven by the first drive circuit 30, as the effective value or amplitude of the single-phase AC voltage increases, The current peak values of the first and second windings increase. Assuming that the effective value or amplitude of the single-phase AC voltage when the current peak value at startup reaches the upper limit value BL is the first reference value VB, the threshold value is set equal to the first reference value VB.

  (3) In the above (2), when the two-phase induction motor 2 is driven by the second drive circuit 60, the maximum rotational speed of the two-phase induction motor 2 increases as the effective value or amplitude of the single-phase AC voltage increases. Will increase. Single phase when the maximum rotation speed of the two-phase induction motor 2 when driven by the second drive circuit 60 reaches the rotation speed of the two-phase induction motor 2 when driven by the first drive circuit 30 Assuming that the effective value or amplitude of the AC voltage is the second reference value VC, when the first reference value VB is less than the second reference value VC, the threshold is set equal to the first reference value VB, When the reference value VB is greater than or equal to the second reference value VC, the threshold value is set equal to the second reference value VC.

  (4) The heat pump device 100 includes a condenser (101 or 103) that condenses the refrigerant, an expansion valve 102 that expands the refrigerant that has passed through the condenser, and an evaporator (103 or 101) that evaporates the refrigerant that has passed through the expansion valve. ) And a compressor 105 that compresses the refrigerant that has passed through the evaporator and discharges the compressed refrigerant to the condenser. The compressor 105 includes a two-phase induction motor 2 that drives a compression mechanism, and the control device 10 described in the above (1) that controls the two-phase induction motor 2.

  (5) In the above (4), the control unit 61 sets the threshold value based on the temperature of the condenser (101 or 103) immediately before the operation of the compressor 105 is started or the ambient temperature of the condenser.

  (6) In the above (5), the control unit 61 decreases the threshold as the temperature of the condenser (101 or 103) or the ambient temperature of the condenser increases.

  (7) In the above (5), when the temperature of the condenser (101 or 103) or the ambient temperature of the condenser is lower than the reference temperature Vth, the control unit 61 sets the threshold value to the condenser temperature or the ambient temperature of the condenser. Set to a constant value VC independent of temperature. When the temperature of the condenser (101 or 103) or the ambient temperature of the condenser is equal to or higher than the reference temperature Vth, the control unit 61 decreases the threshold as the temperature of the condenser or the ambient temperature of the condenser increases.

  (8) In the above (5), the heat pump device is an air conditioner and further includes a four-way valve. The four-way valve switches the refrigerant flow path so that the refrigerant flows from the compressor to the outdoor heat exchanger as a condenser during cooling operation, and the refrigerant flows from the compressor to the indoor heat exchanger as a condenser during heating operation. . The controller 61 sets a threshold value based on the temperature or the outside air temperature of the outdoor heat exchanger 101 during the cooling operation. The controller 61 sets a threshold based on the temperature of the indoor heat exchanger 103 or the room temperature during the heating operation.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Single-phase alternating current power supply, 2 Two-phase induction motor, 3 Rotor, 4 Main winding (1st winding), 5 Auxiliary winding (2nd winding), 10 Control apparatus, 20 Switching circuit, 30 1st Driving circuit (running capacitor circuit), 31 capacitor, 32 switching circuit, 40 converter, 50 inverter, 51 to 56 semiconductor switching element, 60 second driving circuit, 61 control unit, 70, 73, 74 AC voltage detector, 71 , 72 AC current detector, 100 air conditioner (heat pump device), 101 outdoor heat exchanger, 102 expansion valve, 103 indoor heat exchanger, 104 four-way valve, 105 compressor, 106, 107, 108 temperature sensor.

Claims (5)

A control device for a two-phase induction motor,
The two-phase induction motor includes a first winding and a second winding for generating a rotating magnetic field,
The controller is
A switching circuit for switching the supply destination of the single-phase AC voltage;
A first drive circuit for applying the single-phase AC voltage supplied from the switching circuit to the first winding and applying the single-phase AC voltage to the second winding via a capacitor;
A second drive circuit including a converter and an inverter,
The converter converts the single-phase AC voltage supplied from the switching circuit into a DC voltage,
The inverter converts the output DC voltage of the converter into a two-phase AC voltage, applies the converted two-phase AC voltage to the first and second windings,
Further, by performing switching control of the switching circuit, the two-phase induction motor is started and operated using the first drive circuit when the effective value or amplitude of the single-phase AC voltage is not more than a threshold value. A control unit that starts and operates the two-phase induction motor using the second drive circuit when the effective value or amplitude of the single-phase AC voltage exceeds the threshold value. Control device. When the two-phase induction motor is driven by the first drive circuit, the first and second windings at the start of the two-phase induction motor as the effective value or amplitude of the single-phase AC voltage increases. Current peak value increases,
The threshold value is set equal to the first reference value when the effective value or amplitude of the single-phase AC voltage when the current peak value at the time of starting reaches an upper limit value is a first reference value. Item 2. The control device for a two-phase induction motor according to Item 1. When the two-phase induction motor is driven by the second drive circuit, the maximum rotational speed of the two-phase induction motor increases as the effective value or amplitude of the single-phase AC voltage increases.
The single rotation speed when the maximum rotation speed of the two-phase induction motor when driven by the second drive circuit reaches the rotation speed of the two-phase induction motor when driven by the first drive circuit. Assuming that the effective value or amplitude of the phase alternating voltage is the second reference value, when the first reference value is less than the second reference value, the threshold is set equal to the first reference value, The control device for a two-phase induction motor according to claim 2, wherein when the reference value of 1 is equal to or greater than the second reference value, the threshold value is set equal to the second reference value. A condenser that condenses the refrigerant,
An expansion valve for expanding the refrigerant that has passed through the condenser;
An evaporator for evaporating the refrigerant that has passed through the expansion valve;
A compressor that compresses the refrigerant that has passed through the evaporator and discharges the compressed refrigerant to the condenser;
The compressor is
A two-phase induction motor that drives the compression mechanism;
A heat pump device comprising: the control device according to claim 1 that controls the two-phase induction motor.   The heat pump device according to claim 4, wherein the control unit sets the threshold based on a temperature of the condenser immediately before starting operation of the compressor or an ambient temperature of the condenser.