Electric motor drive device and air conditioner

Abstract

An electric motor drive device (100) comprises: a first diode bridge (10); a first capacitor (3); an inverter (30) that drives an electric motor (2); a first relay (40) that switches connection of the first diode bridge (10) and the inverter (30) to a single-phase AC power supply (1); an inrush current limit thermistor (60) that allows flowing of inrush current when power is turned on; a second relay (50) that switches connection of the inrush current limit thermistor (60) to the single-phase AC power supply (1); a second diode bridge (20); a control microcomputer (5); a switching power supply circuit (4) that supplies power to the control microcomputer (5) by means of power supplied through the second diode bridge (20); and a driving microcomputer (7) for the inverter. A half-wave rectifier circuit is configured by using a diode of the second diode bridge, and a current reverse flow preventing circuit is configured by using another diode of the second diode bridge.

Description

[Technical Field]

[0001] The present disclosure relates to an electric motor drive device and an air conditioner. [Background technology]

[0002] Conventionally, there is known a device that uses a single-phase AC power supply to supply an operating voltage to a control microcomputer independently of the supply of operating voltage to the inverter, thereby cutting off the operating voltage to the inverter when the device is not in operation, thereby reducing standby power consumption. Related to this device, there is known a circuit that connects a single diode before a first relay and performs half-wave rectification through the diode to supply operating voltage to the control microcomputer even when the first relay is off, and a method that connects a diode bridge before the first relay and performs full-wave rectification to supply operating voltage to the control microcomputer (see, for example, Patent Document 1).

[0003] Additionally, a circuit is known that, when a command to stop operation is received, turns off the output of a low-dropout regulator that supplies power from a control microcomputer to a drive microcomputer, thereby cutting off power to the inverter control unit while maintaining power to the control microcomputer, thereby reducing standby power consumption (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-177500 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-69538 Summary of the Invention [Problem to be solved by the invention]

[0005] In a conventional circuit that uses a single-phase AC power supply to supply operating voltage to a control microcomputer independently of the supply of operating voltage to the inverter, a circuit that uses two diodes to perform half-wave rectification, a circuit that prevents backflow from the inverter, and a circuit that uses a diode bridge to perform full-wave rectification are provided separately from the circuit that supplies operating voltage to the inverter.These circuits have the problem of increasing the circuit complexity and the number of components, resulting in an increase in the board mounting area.

[0006] The present disclosure has been made in view of the above, and aims to provide an electric motor drive device that uses a single-phase AC power supply and simplifies the circuit for supplying an operating voltage to a control microcomputer independently of the supply of operating voltage to an inverter, thereby reducing the board mounting area. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, an electric motor drive device according to the present disclosure includes a first diode bridge that rectifies a single-phase AC voltage supplied from a single-phase AC power supply into a DC voltage, a first capacitor that smoothes the DC voltage rectified by the first diode bridge, and an inverter that converts the DC voltage smoothed by the first capacitor into an AC voltage and supplies the AC voltage obtained by the conversion to an electric motor to drive the electric motor. The electric motor drive device according to the present disclosure further includes a first relay that can disconnect or connect the first diode bridge and the inverter to the single-phase AC power supply by opening and closing contacts, an inrush current limiting thermistor connected between the contacts of the first relay and that passes an inrush current when power is turned on, and a second relay that is connected to a front stage of the inrush current limiting thermistor and that can disconnect or connect the inrush current limiting thermistor to the single-phase AC power supply. The electric motor drive device according to the present disclosure further includes a second diode bridge connected to a front stage of the first relay and a front stage of the second relay and to the positive side of the first capacitor to supply power to a control system, a control microcomputer that constantly communicates with a plurality of indoor units, a remote controller, and a central controller and issues operation commands to the compressor and the fan motor, a switching power supply circuit that supplies power to the control microcomputer based on the power supplied by the second diode bridge, and a drive microcomputer that receives power via the switching power supply circuit to drive an inverter.The electric motor drive device according to the present disclosure includes a half-wave rectifier circuit formed using some of the diodes included in the second diode bridge, and a circuit that prevents backflow of current from one or both of the inverter and the first capacitor using another part of the diodes included in the second diode bridge. [Effects of the Invention]

[0008] The electric motor drive device according to the present disclosure has the advantage of being able to simplify the circuit for supplying an operating voltage to a control microcomputer using a single-phase AC power supply independently of the supply of operating voltage to an inverter, thereby reducing the board mounting area. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a configuration of an electric motor drive device according to an embodiment; [Figure 2] FIG. 1 is a diagram showing a configuration of a second diode bridge included in an electric motor drive device according to an embodiment; [Figure 3] FIG. 1 is a diagram showing the configuration of an air conditioner according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an electric motor drive device and an air conditioner according to an embodiment will be described in detail with reference to the drawings.

[0011] Embodiment FIG. 1 is a diagram showing the configuration of an electric motor drive device 100 according to an embodiment. For example, the electric motor drive device 100 is provided in an air conditioner. The electric motor drive device 100 drives an electric motor 2. The electric motor 2 is also shown in FIG. 1. When the electric motor drive device 100 is provided in an air conditioner, the electric motor 2 is provided in a compressor of the air conditioner. In the embodiment, the electric motor 2 is a three-phase electric motor. The electric motor 2 is not limited to a three-phase electric motor.

[0012] The electric motor drive device 100 includes a first diode bridge 10 that rectifies a single-phase AC voltage supplied from a single-phase AC power source 1 into a DC voltage. FIG. 1 also shows the single-phase AC power source 1. The electric motor drive device 100 further includes an inverter 30 that converts the DC voltage obtained by the first diode bridge 10 into an AC voltage. The inverter 30 applies the obtained AC voltage to an electric motor 2 to drive the electric motor 2. The electric motor drive device 100 further includes a first capacitor 3 that is located between the first diode bridge 10 and the inverter 30 and is connected to the first diode bridge 10 and the inverter 30. The first capacitor 3 smoothes the DC voltage rectified by the first diode bridge 10. The inverter 30 converts the DC voltage smoothed by the first capacitor 3 into an AC voltage and supplies the AC voltage obtained by the conversion to the electric motor 2 to drive the electric motor 2.

[0013] The electric motor drive device 100 further includes a first relay 40 that can disconnect or connect the first diode bridge 10 and the inverter 30 to the single-phase AC power supply 1 by opening or closing its contacts. The electric motor drive device 100 further includes an inrush current limiting thermistor 60 that is connected between the contacts of the first relay 40 and that passes an inrush current when the power is turned on. Hereinafter, the inrush current limiting thermistor 60 may be referred to as a PTC (Positive Temperature Coefficient) thermistor 60.

[0014] The electric motor drive device 100 further includes a second relay 50 connected to a front end of the PTC thermistor 60 and capable of either disconnecting the PTC thermistor 60 from the single-phase AC power supply 1 or connecting the PTC thermistor 60 to the single-phase AC power supply 1. The front end of the PTC thermistor 60 is the end of the PTC thermistor 60 on the side of the single-phase AC power supply 1. A first contact of the second relay 50 is connected to the single-phase AC power supply 1, and a second contact of the second relay 50 is connected to the PTC thermistor 60.

[0015] The electric motor drive device 100 further includes a second diode bridge 20 connected to the front stage of the first relay 40 and the front stage of the second relay 50 and connected to the positive electrode side of the first capacitor 3. The front stage of the first relay 40 is a contact of the first relay 40 on the side of the single-phase AC power supply 1. The front stage of the second relay 50 is a contact of the second relay 50 on the side of the single-phase AC power supply 1. The second diode bridge 20 supplies power to the control system.

[0016] The motor drive device 100 further includes a control microcomputer 5 that constantly communicates with multiple indoor units, remote controllers, centralized controllers, etc. and issues operation commands to the compressor and fan motor, and a switching power supply circuit 4 that supplies power to the control microcomputer 5 based on the power supplied by the second diode bridge 20.

[0017] The electric motor drive device 100 further includes a drive microcomputer 7 that receives power via the switching power supply circuit 4 to drive the inverter 30, and a low-dropout regulator 6 that receives power via the switching power supply circuit 4 to supply power to the drive microcomputer 7. In FIG. 1, the low-dropout regulator 6 is labeled "regulator 6." The low-dropout regulator 6 is turned on or off based on the output from the control microcomputer 5. In other words, the low-dropout regulator 6 is in one of two states: a state in which it supplies power to the drive microcomputer 7, and a state in which it does not supply power to the drive microcomputer 7, based on the control of the control microcomputer 5.

[0018] While the first relay 40 and the second relay 50 are off, one of the multiple diodes included in the second diode bridge 20 performs half-wave rectification, thereby supplying the operating voltage to the control microcomputer 5 via the switching power supply circuit 4. At this time, another diode included in the second diode bridge 20 prevents current from flowing through the second diode bridge 20 to the first capacitor 3 and the inverter 30, which are separated from the single-phase AC power supply 1 by the first relay 40 and the second relay 50.

[0019] The control microcomputer 5 can reduce the power consumption of the drive microcomputer 7 by turning off the output of the low dropout regulator 6 while the first relay 40 and the second relay 50 are off.

[0020] The electric motor driving device 100 further includes a second smoothing capacitor 9 that smoothes the half-wave rectified voltage output by the second diode bridge 20. The electric motor driving device 100 further includes an inrush current prevention resistor 8 that prevents an inrush current from flowing to the second smoothing capacitor 9 when the power is turned on.

[0021] FIG. 2 is a diagram showing the configuration of a second diode bridge 20 included in the electric motor drive device 100 according to the embodiment. The second diode bridge 20 includes a first diode 21, a second diode 22, a third diode 23, and a fourth diode 24. The connection between the first diode 21 and the fourth diode 24 is connected to a first relay 40 and a second relay 50 via an inrush current prevention resistor 8. The connection between the first diode 21 and the fourth diode 24 is connected to a single-phase AC power supply 1 via an inrush current prevention resistor 8. The first diode 21 and the fourth diode 24 are connected so that a current flows therebetween. The connection between the second diode 22 and the third diode 23 is connected to the positive electrode of the first capacitor 3. The second diode 22 and the third diode 23 are connected so that a current flows therebetween.

[0022] A half-wave rectifier circuit is formed between the junction of the first diode 21 and the second diode 22 and the negative electrode of the first capacitor 3. The first diode 21 and the second diode 22 are connected so as not to allow current to flow. The first diode 21 half-wave rectifies the voltage supplied from the single-phase AC power supply 1 and supplies power to the switching power supply circuit 4. The second diode 22 prevents current from flowing through the second diode bridge 20 to the first capacitor 3 and the inverter 30. The third diode 23 and the fourth diode 24 prevent current from flowing from the first capacitor 3 and the inverter 30 to the single-phase AC power supply 1 through the second diode bridge 20 and from current from the single-phase AC power supply 1 to the first capacitor 3 and the inverter 30 through the second diode bridge 20.

[0023] In the electric motor drive device 100 according to the embodiment, when the first relay 40 and the second relay 50 are turned on and an operating voltage is supplied to the inverter 30, the value of the DC voltage full-wave rectified by the first diode bridge 10 exceeds the value of the DC voltage half-wave rectified by the first diode 21 included in the second diode bridge 20. Therefore, the operating voltage is supplied to the switching power supply circuit 4 via the second diode 22 included in the second diode bridge 20.

[0024] As described above, in the electric motor drive device 100 according to the embodiment, two diodes, the first diode 21 and the second diode 22, out of the four diodes included in the second diode bridge 20, are used to form a half-wave rectifier circuit, and two diodes, the third diode 23 and the fourth diode 24, out of the four diodes included in the second diode bridge 20, are used to form a circuit that prevents backflow of current from one or both of the inverter 30 and the first capacitor 3. This simplifies the circuit and reduces the board mounting area. In other words, the electric motor drive device 100 uses the single-phase AC power supply 1 to simplify the circuit for supplying an operating voltage to the control microcomputer 5 independently of the supply of an operating voltage to the inverter 30, thereby reducing the board mounting area.

[0025] FIG. 3 is a diagram showing the configuration of an air conditioner 200 according to an embodiment. FIG. 3 also shows a single-phase AC power supply 1, which is a power supply source. As shown in FIG. 3, the air conditioner 200 has an electric motor drive device 100 and an electric motor 2. The air conditioner 200 has a compressor 71 including a compression mechanism 77 and the electric motor 2, a four-way valve 72, an outdoor heat exchanger 73, an expansion valve 74, an indoor heat exchanger 75, and refrigerant piping 76. The air conditioner 200 is not limited to a separate-type air conditioner in which the outdoor unit is separated from the indoor unit, but may also be an integrated-type air conditioner in which the compressor 71, the indoor heat exchanger 75, and the outdoor heat exchanger 73 are provided inside a single housing. The electric motor 2 is driven by the electric motor drive device 100.

[0026] The compressor 71 is provided therein with a compression mechanism 77 that compresses the refrigerant, and an electric motor 2 that operates the compression mechanism 77. A refrigeration cycle is formed by the refrigerant circulating through the compressor 71, four-way valve 72, outdoor heat exchanger 73, expansion valve 74, indoor heat exchanger 75, and refrigerant piping 76. The air conditioner 200 is an example of a refrigeration cycle device that has an electric motor drive device 100 and an electric motor 2, but the refrigeration cycle device is not limited to the air conditioner 200 and may be a refrigerator, a heat pump hot water heater, or the like.

[0027] In the air conditioner 200, the electric motor 2 is the drive source for the compressor 71, and the electric motor drive device 100 drives the electric motor 2. However, the electric motor 2 may be used as the drive source for driving an indoor unit blower and an outdoor unit blower (not shown) that the air conditioner 200 has, and the electric motor drive device 100 may drive the electric motor 2. The electric motor 2 may be used as the drive source for the indoor unit blower, the outdoor unit blower, and the compressor 71, and the electric motor drive device 100 may drive the electric motor 2.

[0028] As described above, since the air conditioner 200 has the electric motor drive device 100, the air conditioner 200 can be configured with a circuit that reduces standby power consumption without increasing the board mounting area. Even when the electric motor drive device 100 is applied to a refrigeration cycle device other than the air conditioner 200, the same effects as those obtained by the air conditioner 200 can be obtained.

[0029] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, and parts of the configurations may be omitted or modified without departing from the spirit of the invention. [Explanation of symbols]

[0030] 1 Single-phase AC power supply, 2 Electric motor, 3 First capacitor, 4 Switching power supply circuit, 5 Control microcomputer, 6 Low dropout regulator, 7 Drive microcomputer, 8 Inrush current prevention resistor, 9 Second smoothing capacitor, 10 First diode bridge, 20 Second diode bridge, 21 First diode, 22 Second diode, 23 Third diode, 24 Fourth diode, 30 Inverter, 40 First relay, 50 Second relay, 60 Inrush current limiting thermistor, 71 Compressor, 72 Four-way valve, 73 Outdoor heat exchanger, 74 Expansion valve, 75 Indoor heat exchanger, 76 Refrigerant piping, 77 Compression mechanism, 100 Electric motor drive device, 200 Air conditioner.

Claims

1. a first diode bridge that rectifies a single-phase AC voltage supplied from a single-phase AC power supply into a DC voltage; a first capacitor for smoothing the DC voltage rectified by the first diode bridge; an inverter that converts the DC voltage smoothed by the first capacitor into an AC voltage and supplies the AC voltage obtained by the conversion to an electric motor to drive the electric motor; a first relay that can disconnect or connect the first diode bridge and the inverter to the single-phase AC power supply by opening or closing a contact; an inrush current limiting thermistor connected between contacts of the first relay to allow an inrush current to flow when power is turned on; a second relay connected to a front stage of the inrush current limiting thermistor and capable of disconnecting the inrush current limiting thermistor from the single-phase AC power supply or connecting the inrush current limiting thermistor to the single-phase AC power supply; a second diode bridge connected to a front stage of the first relay and a front stage of the second relay and to a positive electrode of the first capacitor, for supplying power to a control system; a control microcomputer that constantly communicates with the indoor units, the remote controller, and the central controller, and issues operation commands to the compressor and the fan motor; a switching power supply circuit that supplies power to the control microcomputer based on the power supplied by the second diode bridge; a driving microcomputer that receives power from the switching power supply circuit and drives the inverter; Equipped with An electric motor drive device in which some of the diodes included in the second diode bridge are used to form a half-wave rectifier circuit, and another part of the diodes included in the second diode bridge are used to form a circuit that prevents current from flowing back from one or both of the inverter and the first capacitor.

2. An air conditioner comprising the motor drive device according to claim 1.

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