Motor drive device and air conditioner including the same

Abstract

The present invention relates to a motor drive device and an air conditioner including the motor drive device. The motor drive device and the air conditioner including the motor drive device according to an embodiment of the present invention include: a switching device disposed between a motor and an inverter; and a control unit that controls the operating frequency of the motor to be equal to or lower than a first frequency when the winding of the motor changes from a first wiring state to a second wiring, and controls the operating frequency of the motor to be equal to or lower than a second frequency lower than the first frequency when changing from the second wiring to the first wiring. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from being burned out.

Description

Technical Field

[0001] The present invention relates to a motor drive device and an air conditioner including the motor drive device, and more particularly, to a motor drive device capable of preventing burnout of a switching device for changing the wiring of a motor and an air conditioner including the motor drive device. Background Art

[0002] An air conditioner discharges cold and hot air into a room to create a comfortable indoor environment, adjusts the indoor temperature, and purifies the indoor air, thereby providing a more comfortable indoor environment for people. Generally, an air conditioner includes: an indoor unit composed of a heat exchanger and disposed indoors; and an outdoor unit composed of a compressor, a heat exchanger, etc., and supplying refrigerant to the indoor unit.

[0003] On the other hand, in order to improve the power conversion efficiency or the motor drive efficiency when driving a compressor motor in a compressor, in International Patent Application Publication WO19-008756 (hereinafter referred to as "prior art document"), a switching device for changing the winding of a motor to a Y connection or a Δ connection is disclosed.

[0004] However, according to the prior art document, in order to change the winding of a motor to a Y connection or a Δ connection, a mechanical switch or an electronic switch as a switching device is required, and such a switch may be damaged or have a shortened lifespan due to repeated use. Summary of the Invention

[0005] An object of the present invention is to provide a motor drive device and an air conditioner including the motor drive device, which can prevent burnout of a switching device for changing the wiring of a motor.

[0006] Another object of the present invention is to provide a motor drive device and an air conditioner including the motor drive device, which can prevent burnout of an inverter.

[0007] Still another object of the present invention is to provide a motor drive device and an air conditioner including the motor drive device, which can be controlled such that a braking chopper circuit at the dc end does not operate during the operation of the switching device.

[0008] The motor drive device and the air conditioner including the motor drive device according to an embodiment of the present invention for achieving the above objects include: an inverter provided with a plurality of switching elements and outputting an AC power supply to a motor based on a switching operation; a switching device disposed between the inverter and the motor and changing the winding of the motor to a first wiring or a second wiring; and a control unit controlling the inverter and the switching device, when the winding of the motor changes from a first wiring state to a second wiring, the control unit controls the operating frequency of the motor to be below a first frequency, and when changing from the second wiring to the first wiring, controls the operating frequency of the motor to be below a second frequency lower than the first frequency.

[0009] On the other hand, the motor drive device according to an embodiment of the present invention and an air conditioner including the motor drive device may further include: a DC-side capacitor for storing a DC-side voltage; a DC-side voltage detection unit for detecting the DC-side voltage; and a braking chopper circuit connected to both ends of the DC-side capacitor and including a resistance element and a switching element.

[0010] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring, the control unit may control the operating frequency of the motor to be below a first frequency so that the detected DC-side voltage is below an allowable voltage.

[0011] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring, the control unit may control the output of the inverter to stop. After the output of the inverter stops, the regenerative current from the motor is supplied to the DC side via the switching device and the inverter, and the control unit may control the operating frequency of the motor to be below a first frequency so that the detected DC-side voltage is below an allowable voltage during the supply of the regenerative current.

[0012] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring, the control unit may control the operating frequency of the motor to be reduced to below a first frequency so that the switching element in the braking chopper circuit is not turned on.

[0013] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring, the control unit may control the output of the inverter to stop. After the output of the inverter stops, the control unit may control the first regenerative current from the motor to be supplied to the DC side, and then supply a second regenerative current lower than the first regenerative current to the DC side so that the switching element in the braking chopper circuit is not turned on.

[0014] On the other hand, when the winding of the motor changes from the second wiring state to the first wiring, the control unit may control the operating frequency of the motor to be below a second frequency so that the detected DC-side voltage is below an allowable voltage.

[0015] On the other hand, when the winding of the motor changes from the second wiring state to the first wiring, the control unit may control the output of the inverter to stop. After the output of the inverter stops, the regenerative current from the motor is supplied to the DC side via the switching device and the inverter, and the control unit may control the operating frequency of the motor to be below a second frequency so that the detected DC-side voltage is below an allowable voltage during the supply of the regenerative current.

[0016] On the other hand, when the winding of the motor changes from the second wiring state to the first wiring, the control unit may control the operating frequency of the motor to be reduced to below a second frequency so that the switching element in the braking chopper circuit is not turned on.

[0017] On the other hand, when the windings of the motor are switched from the second wiring state to the first wiring, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the control unit can control the third regenerative current from the motor to be supplied to the DC terminal, and then cause a fourth regenerative current lower than the third regenerative current to be supplied to the DC terminal, so that the switching element in the braking chopper circuit is not turned on.

[0018] On the other hand, the control unit can be controlled such that the range of the operating frequency of the motor when the windings of the motor are changed from the first wiring state to the second wiring is larger than the range of the operating frequency of the motor when the second wiring is changed to the first wiring.

[0019] On the other hand, when the windings of the motor are changed from the first wiring state to the second wiring, the control unit can control the operating frequency of the motor to be equal to or higher than the first reference frequency. When changing from the second wiring to the first wiring, the control unit can control the operating frequency of the motor to be equal to or higher than the second reference frequency.

[0020] On the other hand, the motor drive device according to an embodiment of the present invention and an air conditioner including the motor drive device further include a temperature detection unit that is attached to the inverter to detect the temperature of the inverter. When the windings of the motor are changed from the first wiring state to the second wiring, the control unit can control the temperature of the inverter to be equal to or lower than the first reference temperature. When changing from the second wiring to the first wiring, the control unit controls the temperature of the inverter to be equal to or lower than the second reference temperature, which is higher than the first reference temperature.

[0021] A motor drive device according to another embodiment of the present invention for achieving the above object and an air conditioner including the motor drive device include: an inverter provided with a plurality of switching elements that outputs an AC power supply to the motor based on a switching operation; a temperature detection unit attached to the inverter to detect the temperature of the inverter; a switching device disposed between the inverter and the motor that changes the windings of the motor to the first wiring or the second wiring; and a control unit that controls the inverter and the switching device. When the windings of the motor are changed from the first wiring state to the second wiring, the control unit controls the temperature of the inverter to be equal to or lower than the first reference temperature. When changing from the second wiring to the first wiring, the control unit controls the temperature of the inverter to be equal to or lower than the second reference temperature, which is higher than the first reference temperature.

[0022] On the other hand, a motor drive device according to another embodiment of the present invention and an air conditioner including the motor drive device further include: a DC-side capacitor for storing a DC-side voltage; a DC-side voltage detection unit for detecting the DC-side voltage; and a braking chopper circuit connected to both ends of the DC-side capacitor and including a resistance element and a switching element. When the winding of the motor changes from a first wiring state to a second wiring state, the control unit can control the detected DC-side voltage to be below an allowable voltage. When the winding of the motor changes from the first wiring state to the second wiring state, the control unit can control the temperature of the inverter to be below a second reference temperature higher than the first reference temperature.

[0023] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring state, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the regenerative current from the motor is supplied to the DC side via the switching device and the inverter, and the control unit can control the temperature of the inverter to be below the first reference temperature so that, during the supply of the regenerative current, the detected DC-side voltage is below the allowable voltage.

[0024] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring state, the control unit can control the temperature of the inverter to be lowered below the first reference temperature so that the switching element in the braking chopper circuit is not turned on.

[0025] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring state, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the control unit can control the first regenerative current from the motor to be supplied to the DC side, and then supply a second regenerative current lower than the first regenerative current to the DC side so that the switching element in the braking chopper circuit is not turned on.

[0026] On the other hand, when the winding of the motor changes from the second wiring state to the first wiring state, the control unit can control the temperature of the inverter to be below the second reference temperature so that the detected DC-side voltage is below the allowable voltage.

[0027] On the other hand, when the winding of the motor changes from the second wiring state to the first wiring state, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the regenerative current from the motor is supplied to the DC side via the switching device and the inverter, and the control unit can control the temperature of the inverter to be below the second reference temperature so that, during the supply of the regenerative current, the detected DC-side voltage is below the allowable voltage.

[0028] On the other hand, when the winding of the motor changes from the second wiring state to the first wiring state, the control unit can control the temperature of the inverter to be lowered below the second reference temperature so that the switching element in the braking chopper circuit is not turned on.

[0029] On the other hand, when the winding of the motor is switched from the second wiring state to the first wiring, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the control unit can control the third regenerative current from the motor to be supplied to the DC terminal, and then supply a fourth regenerative current lower than the third regenerative current to the DC terminal so that the switching element in the braking chopper circuit is not turned on.

[0030] The motor drive device according to an embodiment of the present invention and an air conditioner including the motor drive device include: a switching device disposed between the motor and the inverter; and a control unit that controls the operating frequency of the motor to be below a first frequency when the winding of the motor is changed from a first wiring state to a second wiring state, and controls the operating frequency of the motor to be below a second frequency lower than the first frequency when changed from the second wiring to the first wiring. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from being burned out. In addition, it is possible to prevent the inverter from being burned out.

[0031] On the other hand, the motor drive device according to an embodiment of the present invention and an air conditioner including the motor drive device may further include: a DC terminal capacitor for storing the DC terminal voltage; a DC terminal voltage detection unit for detecting the DC terminal voltage; and a braking chopper circuit connected to both ends of the DC terminal capacitor and including a resistance element and a switching element. Thereby, it can be controlled that the braking chopper circuit at the DC terminal does not operate during the operation of the switching device.

[0032] On the other hand, when the winding of the motor is changed from the first wiring state to the second wiring state, the control unit can control the operating frequency of the motor to be below a first frequency so that the detected DC terminal voltage is below the allowable voltage. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from being burned out. In addition, it is possible to prevent the inverter from being burned out.

[0033] On the other hand, when the winding of the motor is switched from the first wiring state to the second wiring state, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the regenerative current from the motor is supplied to the DC terminal via the switching device and the inverter, and the control unit can control the operating frequency of the motor to be below a first frequency so that the detected DC terminal voltage is below the allowable voltage during the supply of the regenerative current. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from being burned out. In addition, it is possible to prevent the inverter from being burned out.

[0034] On the other hand, when the winding of the motor is changed from the first wiring state to the second wiring state, the control unit can control the operating frequency of the motor to be reduced to below a first frequency so that the switching element in the braking chopper circuit is not turned on. Thereby, it can be controlled that the braking chopper circuit at the DC terminal does not operate during the operation of the switching device. As a result, it is possible to prevent the switching device for changing the wiring of the motor from being burned out.

[0035] On the other hand, when the winding of the motor is switched from the first wiring state to the second wiring, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the control unit can control the first regenerative current from the motor to be supplied to the DC terminal, and then supply a second regenerative current lower than the first regenerative current to the DC terminal so that the switching element in the braking chopper circuit is not turned on. Thus, it can be controlled that the braking chopper circuit at the DC terminal does not operate during the operation of the switching device. As a result, it is possible to prevent the switching device for changing the wiring of the motor from burning out.

[0036] On the other hand, when the winding of the motor is changed from the second wiring state to the first wiring, the control unit can control the operating frequency of the motor to be equal to or lower than the second frequency so that the detected DC terminal voltage is equal to or lower than the allowable voltage. Thus, it is possible to prevent the switching device for changing the wiring of the motor from burning out. In addition, it is possible to prevent the inverter from burning out.

[0037] On the other hand, when the winding of the motor is changed from the second wiring state to the first wiring, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the regenerative current from the motor is supplied to the DC terminal via the switching device and the inverter, and the control unit can control the operating frequency of the motor to be equal to or lower than the second frequency so that the detected DC terminal voltage is equal to or lower than the allowable voltage during the supply of the regenerative current. Thus, it is possible to prevent the switching device for changing the wiring of the motor from burning out. In addition, it is possible to prevent the inverter from burning out.

[0038] On the other hand, when the winding of the motor is changed from the second wiring state to the first wiring, the control unit can control the operating frequency of the motor to be reduced to equal to or lower than the second frequency so that the switching element in the braking chopper circuit is not turned on. Thus, it can be controlled that the braking chopper circuit at the DC terminal does not operate during the operation of the switching device. As a result, it is possible to prevent the switching device for changing the wiring of the motor from burning out.

[0039] On the other hand, when the winding of the motor is switched from the second wiring state to the first wiring, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the control unit can control the third regenerative current from the motor to be supplied to the DC terminal, and then supply a fourth regenerative current lower than the third regenerative current to the DC terminal so that the switching element in the braking chopper circuit is not turned on. Thus, it can be controlled that the braking chopper circuit at the DC terminal does not operate during the operation of the switching device. As a result, it is possible to prevent the switching device for changing the wiring of the motor from burning out.

[0040] On the other hand, the control unit can control the range of the operating frequency of the motor when the winding of the motor is changed from the first wiring state to the second wiring to be larger than the range of the operating frequency of the motor when the winding is changed from the second wiring to the first wiring. Thus, it is possible to prevent the switching device for changing the wiring of the motor from burning out. In addition, it is possible to prevent the inverter from burning out.

[0041] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring, the control unit can control the operating frequency of the motor to be equal to or higher than the first reference frequency. When changing from the second wiring to the first wiring, the control unit can control the operating frequency of the motor to be equal to or higher than the second reference frequency. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from burning out. In addition, it is possible to prevent the inverter from burning out.

[0042] On the other hand, the motor drive device according to an embodiment of the present invention and an air conditioner including the motor drive device further include a temperature detection unit attached to the inverter to detect the temperature of the inverter. When the winding of the motor changes from the first wiring state to the second wiring, the control unit can control the temperature of the inverter to be equal to or lower than the first reference temperature. When changing from the second wiring to the first wiring, the control unit can control the temperature of the inverter to be equal to or lower than the second reference temperature, which is higher than the first reference temperature. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from burning out. In addition, it is possible to prevent the inverter from burning out.

[0043] The motor drive device according to another embodiment of the present invention for achieving the above object and an air conditioner including the motor drive device include: an inverter provided with a plurality of switching elements that outputs an AC power supply to the motor based on a switching operation; a temperature detection unit attached to the inverter to detect the temperature of the inverter; a switching device disposed between the inverter and the motor that changes the winding of the motor to the first wiring or the second wiring; and a control unit that controls the inverter and the switching device. When the winding of the motor changes from the first wiring state to the second wiring, the control unit controls the temperature of the inverter to be equal to or lower than the first reference temperature. When changing from the second wiring to the first wiring, the control unit controls the temperature of the inverter to be equal to or lower than the second reference temperature, which is higher than the first reference temperature. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from burning out. In addition, it is possible to prevent the inverter from burning out.

[0044] On the other hand, the motor drive device according to another embodiment of the present invention and an air conditioner including the motor drive device further include: a DC-side capacitor for storing a DC-side voltage; a DC-side voltage detection unit for detecting the DC-side voltage; and a braking chopper circuit connected to both ends of the DC-side capacitor and including a resistance element and a switching element. When the winding of the motor changes from the first wiring state to the second wiring, the control unit can control the detected DC-side voltage to be equal to or lower than the allowable voltage. When the winding of the motor changes from the first wiring state to the second wiring, the control unit can control the temperature of the inverter to be equal to or lower than the second reference temperature, which is higher than the first reference temperature. Thereby, it is possible to control the braking chopper circuit on the DC side not to operate during the operation of the switching device. As a result, it is possible to prevent the switching device for changing the wiring of the motor from burning out.

[0045] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the regenerative current from the motor is supplied to the DC terminal via the switching device and the inverter, and the control unit can control the temperature of the inverter to be below the first reference temperature so that the detected DC terminal voltage is below the allowable voltage during the supply of the regenerative current. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from burning out. In addition, it is possible to prevent the inverter from burning out.

[0046] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring, the control unit can control the temperature of the inverter to be reduced below the first reference temperature so that the switching element in the braking chopper circuit is not turned on. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from burning out. In addition, it is possible to prevent the inverter from burning out.

[0047] On the other hand, when the winding of the motor changes from the first wiring state to the second wiring, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the control unit can control the first regenerative current from the motor to be supplied to the DC terminal, and then supply the second regenerative current lower than the first regenerative current to the DC terminal so that the switching element in the braking chopper circuit is not turned on. Thereby, it can be controlled that the braking chopper circuit at the DC terminal does not operate during the operation of the switching device. As a result, it is possible to prevent the switching device for changing the wiring of the motor from burning out.

[0048] On the other hand, when the winding of the motor changes from the second wiring state to the first wiring, the control unit can control the temperature of the inverter to be below the second reference temperature so that the detected DC terminal voltage is below the allowable voltage. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from burning out. In addition, it is possible to prevent the inverter from burning out.

[0049] On the other hand, when the winding of the motor changes from the second wiring state to the first wiring, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the regenerative current from the motor is supplied to the DC terminal via the switching device and the inverter, and the control unit can control the temperature of the inverter to be below the second reference temperature so that the detected DC terminal voltage is below the allowable voltage during the supply of the regenerative current. Thereby, it is possible to prevent the switching device for changing the wiring of the motor from burning out. In addition, it is possible to prevent the inverter from burning out.

[0050] On the other hand, when the winding of the motor changes from the second wiring state to the first wiring, the control unit can control the temperature of the inverter to be reduced below the second reference temperature so that the switching element in the braking chopper circuit is not turned on. Thereby, it can be controlled that the braking chopper circuit at the DC terminal does not operate during the operation of the switching device. As a result, it is possible to prevent the switching device for changing the wiring of the motor from burning out.

[0051] On the other hand, when the winding of the motor is switched from the second wiring state to the first wiring, the control unit can control the output of the inverter to stop. After the output of the inverter stops, the control unit can control the third regenerative current to be supplied from the motor to the DC terminal, and then supply a fourth regenerative current lower than the third regenerative current to the DC terminal so that the switching element in the braking chopper circuit is not turned on. Thus, it can be controlled that the braking chopper circuit at the DC terminal does not operate during the operation of the switching device. As a result, it is possible to prevent the switching device for changing the wiring of the motor from being burned out. Description of the Drawings

[0052] Figure 1 It is a diagram showing the structure of an air conditioner according to an embodiment of the present invention.

[0053] Figure 2 It is Figure 1 a schematic diagram of the outdoor unit and the indoor unit of

[0054] Figure 3 It is Figure 1 a simplified internal block diagram of the air conditioner of

[0055] Figure 4 It shows an example of the internal block diagram of the motor drive device according to an embodiment of the present invention.

[0056] Figure 5 It is Figure 4 an example of the internal circuit diagram of the motor drive device of

[0057] Figure 6 It is Figure 5 the internal block diagram of the inverter control unit of

[0058] Figure 7 It is a diagram referred to when explaining Figure 4 the operation of the switching device of

[0059] Figure 8a and Figure 8b It is a timing chart showing Figure 7 the winding switching operation of the switching device of

[0060] Figures 9a to 9i It is a diagram referred to when explaining Figure 4 the operation of the switching device of

[0061] Figure 10 It is a flowchart showing the operation method of the motor drive device according to an embodiment of the present invention.

[0062] Figures 11 to 13b It is a diagram referred to when explaining Figure 10 the operation method of

[0063] Figure 14This is a flowchart showing an operating method of a motor driving device according to another embodiment of the present invention.

[0064] Figure 15 This is a flowchart showing an operating method of a motor driving device according to still another embodiment of the present invention.

[0065] Figure 16 Yes Figure 15 Figure to refer to when explaining the actions of DETAILED DESCRIPTION

[0066] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

[0067] The suffixes "module" and "unit" of the structural elements used in the following description are only given for the convenience of writing this specification, and they themselves do not have a particularly important meaning or function. Therefore, the above-mentioned "module" and "unit" can be used interchangeably.

[0068] Figure 1 This is a diagram illustrating the structure of an air conditioner according to an embodiment of the present invention.

[0069] like Figure 1 As shown, the air conditioner of the present invention is a large air conditioner 100, which may include: a plurality of indoor units 31, 32, 33, 34, 35; a plurality of outdoor units 21, 22, connected to the plurality of indoor units; remote controllers 41, 42, 43, 44, 45, respectively connected to the plurality of indoor units; and a remote controller 10, for controlling the plurality of indoor units and outdoor units.

[0070] The remote controller 10 is connected to the plurality of indoor units 31, 32, 33, 34, 35 and the plurality of outdoor units 21, 22 to monitor and control their operations. At this time, the remote controller 10 can be connected to the plurality of indoor units to perform operation settings, lock settings, schedule control, group control, etc. of the indoor units.

[0071] The air conditioner 100 may be applied to any of a vertical air conditioner, a wall-mounted air conditioner, and a ceiling-mounted air conditioner. However, for ease of description, the following description will take a ceiling-mounted air conditioner as an example.

[0072] In addition, the air conditioner may further include at least one of a ventilation device, an air purification device, a humidification device, and a heater, and may operate in conjunction with the operation of the indoor unit and the outdoor unit.

[0073] The outdoor units 21 and 22 include: a compressor (not shown) that receives and compresses refrigerant; an outdoor heat exchanger (not shown) that exchanges heat between the refrigerant and outdoor air; a liquid receiver (not shown) that extracts gaseous refrigerant from the supplied refrigerant and supplies it to the compressor; and a four-way valve (not shown) that selects the refrigerant flow path according to the heating operation. Additionally, it also includes a plurality of sensors, valves, an oil recovery device, etc., but in the following description, the explanation of their structures will be omitted.

[0074] The outdoor units 21 and 22 operate the compressor and outdoor heat exchanger they have, compress or exchange heat for the refrigerant according to the setting, and supply the refrigerant to the indoor units 31, 32, 33, 34, and 35. The outdoor units 21 and 22 are driven according to the request of the remote controller 10 or the indoor units 31, 32, 33, 34, and 35, and as the cooling and heating capacity changes corresponding to the driven indoor units, the number of operating outdoor units and the number of operating compressors provided in the outdoor units change.

[0075] At this time, the outdoor units 21 and 22 will be described taking the example of a plurality of outdoor units supplying refrigerant to the respectively connected indoor units, but depending on the connection structure of the outdoor units and indoor units, a plurality of outdoor units can also be connected to each other and supply refrigerant to a plurality of indoor units.

[0076] The indoor units 31, 32, 33, 34, and 35 are connected to any one of the plurality of outdoor units 21 and 22, and receive the refrigerant and discharge hot and cold air indoors. The indoor units 31, 32, 33, 34, and 35 include an indoor heat exchanger (not shown), an indoor unit fan (not shown), an expansion valve (not shown) for expanding the supplied refrigerant, and a plurality of sensors (not shown).

[0077] At this time, the outdoor units 21 and 22 and the indoor units 31, 32, 33, 34, and 35 are connected by communication lines and exchange data with each other. The outdoor units and indoor units are connected to the remote controller 10 by separate communication lines and operate according to the control of the remote controller 10.

[0078] The remote controllers 41, 42, 43, 44, and 45 can be respectively connected to the indoor units, input user control instructions to the indoor units, and receive and display the status information of the indoor units. At this time, the remote controllers can communicate in a wired or wireless manner according to the connection form with the indoor units, and in some cases, a plurality of indoor units can be connected to one remote controller, and the settings of the plurality of indoor units can be changed through the input of one remote controller.

[0079] Additionally, the remote controllers 41, 42, 43, 44, and 45 can include a temperature detection sensor inside.

[0080] Figure 2 Yes Figure 1Schematic diagram of the outdoor unit and the indoor unit.

[0081] As shown in the accompanying drawings, the air conditioner 100 is generally divided into an indoor unit 31 and an outdoor unit 21.

[0082] The outdoor unit 21 includes: a compressor 102 that compresses the refrigerant; a compressor motor 102b that drives the compressor; an outdoor heat exchanger 104 that dissipates heat from the compressed refrigerant; an outdoor blower 105 disposed on one side of the outdoor heat exchanger 104, which is composed of an outdoor fan 105a for promoting the heat dissipation of the refrigerant and a motor 105b for rotating the outdoor fan 105a; an expansion mechanism 106 that expands the condensed refrigerant; a refrigeration / heating switching valve 110 that changes the flow path of the compressed refrigerant; and a liquid receiver 103 that temporarily stores the gaseous refrigerant, removes moisture and foreign matters, and then supplies the refrigerant at a specified pressure to the compressor.

[0083] The indoor unit 31 includes: an indoor heat exchanger 108 disposed indoors and performing refrigeration and heating functions; an indoor blower 109 disposed on one side of the indoor heat exchanger 108, which is composed of an indoor fan 109a for promoting the heat dissipation of the refrigerant and a motor 109b for rotating the indoor fan 109a.

[0084] At least one indoor heat exchanger 108 may be provided. The compressor 102 may be at least one of a variable frequency compressor and a constant speed compressor.

[0085] In addition, the air conditioner 100 may be composed of a refrigeration mechanism for cooling the indoor space, or may be composed of a heat pump for cooling or heating the indoor space.

[0086] On the other hand, Figure 2 One indoor unit 31 and one outdoor unit 21 are shown, but the driving device of the air conditioner according to the embodiment of the present invention is not limited thereto, and it is obvious that it can be applied to a multi-split air conditioner having a plurality of indoor units and outdoor units, an air conditioner having one indoor unit and a plurality of outdoor units, etc.

[0087] Figure 1 The compressor 102 in the outdoor unit 21 can be driven by a motor driving device 200 for driving a compressor motor 230.

[0088] Figure 3 is Figure 1 A simplified internal block diagram of the air conditioner.

[0089] As shown in the accompanying drawings, Figure 3The air conditioner 100 includes a compressor 102, an outdoor fan 105a, an indoor fan 109a, a control unit 170, a discharge temperature detection unit 118, an outdoor temperature detection unit 138, an indoor temperature detection unit 158, and a memory 140.

[0090] In addition, the air conditioner 100 may further include a compressor drive unit 220, an outdoor fan drive unit 200, an indoor fan drive unit 300, a switching valve 110, an expansion valve 106, a display unit 130, and an input unit 120.

[0091] For the description of the compressor 102, the outdoor fan 105a, and the indoor fan 109a, refer to Figure 2 .

[0092] The input unit 120 is provided with a plurality of operation buttons and transmits a signal regarding the operation target temperature of the air conditioner 100 to the control unit 170.

[0093] The display unit 130 can display the operation state of the air conditioner 100.

[0094] The memory 140 can store data required for the operation of the air conditioner 100.

[0095] The discharge temperature detection unit 118 can detect the refrigerant discharge temperature Tc in the compressor 102 and can transmit a signal corresponding to the detected refrigerant discharge temperature Tc to the control unit 170.

[0096] The outdoor temperature detection unit 138 can detect the temperature around the outdoor unit 21 of the air conditioner 100, i.e., the outdoor temperature To, and can transmit a signal corresponding to the detected outdoor temperature To to the control unit 170.

[0097] The indoor temperature detection unit 158 can detect the temperature around the indoor unit 31 of the air conditioner 100, i.e., the indoor temperature Ti, and can transmit a signal corresponding to the detected indoor temperature Ti to the control unit 170.

[0098] The control unit 170 can control the operation of the air conditioner 100 based on at least one of the detected refrigerant discharge temperature Tc, the detected outdoor temperature To, the detected indoor temperature Ti, and the input target temperature. For example, the final target superheat can be calculated, and the operation of the air conditioner 100 can be controlled.

[0099] On the other hand, as shown in the figure, in order to control the operations of the compressor 102, the indoor fan 109a, and the outdoor fan 105a, the control unit 170 can control the compressor drive unit 220, the outdoor fan drive unit 200, and the indoor fan drive unit 300 respectively.

[0100] For example, the control unit 170 may output corresponding speed command value signals to the compressor drive unit 220, the outdoor fan drive unit 200, or the indoor fan drive unit 300 respectively based on the target temperature.

[0101] Moreover, the compressor electric motor (102b), the motor of the outdoor blower (105b), and the motor of the indoor blower 109b may operate at the target rotational speeds respectively based on their respective speed command value signals.

[0102] On the other hand, in addition to controlling the compressor drive unit 220, the outdoor fan drive unit 200, or the indoor fan drive unit 300, the control unit 170 may also control the operation of the entire air conditioner 100.

[0103] For example, the control unit 170 may control the operation of the cooling / heating switching valve 110 or the four-way valve.

[0104] Alternatively, the control unit 170 may control the operation of the expansion mechanism or the expansion valve 106.

[0105] Figure 4 An example of the internal block diagram of the motor drive device showing an embodiment of the present invention Figure 5 is Figure 4 an example of the internal circuit diagram of the motor drive device.

[0106] As will be described with reference to the drawings, the motor drive device 220 of the embodiment of the present invention is used to drive a motor in a sensorless manner and may be referred to as a power conversion device.

[0107] The motor drive device 220 of the embodiment of the present invention may include a converter 410, a braking chopper circuit 415, an inverter 420, an inverter control unit 430, a switching device 450, a dc terminal voltage detection unit B, a dc capacitor C, an output current detection unit E, and an output voltage detection unit F. In addition, the motor drive device 220 may also include an input current detection unit A, etc.

[0108] The input current detection unit A may detect the input current i input from the commercial AC power supply 405 s . For this purpose, a CT (current transformer) or a shunt resistor may be used as the input current detection unit A. The detected input current i s may be input to the inverter control unit 430 as a discrete signal in pulse form.

[0109] Converter 410 converts the commercial AC power supply 405 passing through the reactor L into a DC power supply and outputs it. In the drawings, the commercial AC power supply 405 is shown as a three-phase AC power supply, but it can also be a single-phase AC power supply. Depending on the type of the commercial AC power supply 405, the internal structure of the converter 410 will also be different.

[0110] On the other hand, the converter 410 is composed of diodes and the like and does not have switching elements, so that it can perform a rectification operation without additional switching operations.

[0111] For example, in the case of a three-phase AC power supply, the converter 410 can have six diodes in a bridge configuration, and in the case of a single-phase AC power supply, the converter 410 can have four diodes in a bridge configuration.

[0112] On the other hand, in the case of a three-phase AC power supply, the converter 410 can have six switching elements and six diodes, and in the case of a single-phase AC power supply, the converter 410 can also be a half-bridge type converter having two switching elements and four diodes.

[0113] When the converter 410 has switching elements, through the switching operations of the corresponding switching elements, it is possible to perform a boost operation, power factor improvement, and DC power supply conversion.

[0114] The dc-side capacitor C is arranged at the dc side and stores the power supply output from the converter 410. In the drawings, one element is illustrated as the dc-side capacitor C, but a plurality of them can also be provided to ensure the stability of the elements.

[0115] On the other hand, in the drawings, it is illustrated as being connected to the output terminal of the converter 410, but it is not limited thereto, and a DC power supply can also be directly input.

[0116] For example, the DC power supply from a solar cell can be directly input to the dc-side capacitor C, or it can also be input after DC / DC conversion. Hereinafter, the description will be mainly based on the parts illustrated in the drawings.

[0117] On the other hand, since a DC power supply is stored across the dc-side capacitor C at n1 - n2, it can be referred to as the dc side or the dc link side.

[0118] The dc-side voltage detection unit B can detect both ends of the dc-side capacitor C, that is, the dc-side voltage Vdc. For this purpose, the dc-side voltage detection unit B can include a resistance element, an amplifier, etc. The detected dc-side voltage Vdc is a discrete signal in a pulse form and can be input to the inverter control unit 430.

[0119] The braking chopper circuit 415 may be configured across the DC-link capacitor C and may include a resistor element Rp and a switching element Sp.

[0120] Specifically, a diode element Dp and a resistor element Rp are connected in parallel across one end n1 of the DC-link capacitor C, and the switching element Sp is connected to the other end n2 of the DC-link capacitor C.

[0121] The cathode terminal of the diode element Dp is connected to one end n1 of the DC-link capacitor C, and the anode terminal of the diode element Dp is connected to the n3 terminal between the resistor element Rp and the switching element Sp.

[0122] When the DC-link voltage Vdc exceeds the allowable voltage, the braking chopper circuit 415 operates, and when the DC-link voltage Vdc is below the allowable voltage, the braking chopper circuit 415 does not operate.

[0123] Specifically, when the DC-link voltage Vdc exceeds the allowable voltage, the switching element Sp of the braking chopper circuit 415 is turned on, and current flows through the resistor element Rp and the switching element Sp, whereby the DC-link voltage Vdc is reduced.

[0124] On the other hand, when the DC-link voltage Vdc is below the allowable voltage, the switching element Sp of the braking chopper circuit 415 is turned off, and current does not flow through the resistor element Rp and the switching element Sp.

[0125] Thus, by the operation of the braking chopper circuit 415, it is possible to prevent a sharp rise in the DC-link voltage due to the regenerative current, and thereby prevent burnout of the DC-link capacitor C and the like.

[0126] In particular, in the case where the DC-link capacitor C is composed of a film capacitor, burnout of the DC-link capacitor C and the like can be prevented.

[0127] The inverter 420 may be provided with a plurality of inverter switching elements Sa to Sc, S'a to S'c, and by the on / off operation of the switching elements, the DC power supply Vdc at the DC-link is converted into a three-phase AC power supply va, vb, vc and output to the three-phase synchronous motor 230.

[0128] In the inverter 420, the upper-arm switching elements Sa, Sb, Sc and the lower-arm switching elements S'a, S'b, S'c, which are connected in series with each other respectively, form a pair, and a total of three pairs of upper-arm and lower-arm switching elements are connected in parallel (Sa&S'a, Sb&S'b, Sc&S'c) to each other. Diodes are anti-parallel connected in each of the switching elements Sa, S'a, Sb, S'b, Sc, S'c.

[0129] A plurality of switching elements in the inverter 420 perform conduction / disconnection operations based on the inverter switching control signal Sic from the inverter control unit 430. Thereby, a three-phase AC power supply having a specified frequency is output to the three-phase synchronous motor 230.

[0130] The temperature detection unit DT is attached to the inverter 420 and can detect the temperature of the inverter 420. The detected temperature can be transmitted to the inverter control unit 430.

[0131] The inverter control unit 430 can control the switching operation of the inverter 420 based on a sensorless method. For this purpose, the inverter control unit 430 can receive the output current io detected by the output current detection unit E.

[0132] To control the switching operation of the inverter 420, the inverter control unit 430 outputs the inverter switching control signal Sic to the inverter 420. The inverter switching control signal Sic is a switching control signal of the pulse width modulation method (PWM), which is generated and output based on the output current io detected by the output current detection unit E. Refer to Figure 6 , the detailed operation related to the output of the inverter switching control signal Sic in the inverter control unit 430 will be described later.

[0133] The output current detection unit E detects the output current io flowing between the inverter 420 and the three-phase motor 230. That is, the current flowing in the motor 230 is detected. The output current detection unit E can detect the output currents ia, ib, ic of all phases, or can also detect the output currents of two phases using three-phase balance.

[0134] The output current detection unit E can be located between the inverter 420 and the motor 230. To perform current detection, a CT (current transformer) or a shunt resistor can be used.

[0135] In the case of using shunt resistors, three shunt resistors can be located between the inverter 420 and the synchronous motor 230, or one end of each can be connected to the three lower arm switching elements S'a, S'b, S'c of the inverter 420, respectively.

[0136] On the other hand, two shunt resistors can also be used using three-phase balance. On the other hand, in the case of using one shunt resistor, the corresponding shunt resistor can also be arranged between the capacitor C and the inverter 420.

[0137] The detected output current io is a discrete signal in the form of a pulse, which can be applied to the inverter control unit 430, and an inverter switch control signal Sic is generated based on the detected output current io. Hereinafter, the detected output current io may also be described in parallel as the three-phase output currents ia, ib, and ic.

[0138] The output voltage detection unit F can detect the output voltage vo output from the inverter 420. Specifically, the output voltage vo of each phase output from the inverter 420 can be detected. For this purpose, the output voltage detection unit F may include a resistance element, an amplifier, etc. The detected output voltage vo is a discrete signal in the form of a pulse and can be input to the inverter control unit 430.

[0139] On the other hand, the three-phase motor 230 is provided with a stator and a rotor, and the rotor is rotated by applying an alternating current power supply of each phase with a specified frequency to the coils of the stator of each phase (phase a, phase b, phase c).

[0140] Such a motor 230 may include, for example, a Surface-Mounted Permanent-Magnet Synchronous Motor (SMPMSM), an Interior Permanent Magnet Synchronous Motor (IPMSM), and a Synchronous Reluctance Motor (Synrm), etc. Among them, SMPMSM and IPMSM are Permanent Magnet Synchronous Motors (PMSM) that apply permanent magnets, and Synrm is characterized by not having a permanent magnet.

[0141] On the other hand, the switching device 450 may be arranged between the inverter 420 and the motor 230, and the windings of the motor 230 can be converted into a first wiring or a second wiring.

[0142] Among them, the first wiring may represent a Y wiring, and the second wiring may be a Δ wiring.

[0143] For this purpose, the switching device 450 may include three relay elements SW1, SW2, and SW3 respectively connected between the three-phase output terminals of the inverter 420 and the three-phase coils CA, CB, and CC of the motor 230.

[0144] That is, the switching device 450 may include a first relay element SW1, a second relay element SW2, and a third relay element SW3 that are electrically connected to the respective phase outputs.

[0145] When the motor 230 is at the first speed or below the first operating frequency, the switching device 450 may operate to place the motor 230 in the first wiring, and when the motor 230 exceeds the first speed or the first operating frequency, the switching device 450 may operate to place the motor 230 in the second wiring. Thereby, the power conversion efficiency or the motor drive efficiency can be improved.

[0146] In particular, the power conversion efficiency or the motor drive efficiency at low speeds below the first speed or the first operating frequency can be improved.

[0147] On the other hand, the motor drive device 220 according to an embodiment of the present invention includes: a switching device 450 disposed between the motor 230 and the inverter 420; and a control unit 170 or an inverter control unit 430 that controls the operating frequency of the motor 230 to be below the first frequency when the winding of the motor 230 changes from the first wiring state to the second wiring, and controls the operating frequency of the motor 230 to be below a second frequency lower than the first frequency when changing from the second wiring to the first wiring. Thereby, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out. In addition, it is possible to prevent the inverter 420 from being burned out. Regarding this, refer to Figure 7 The following will be described in detail.

[0148] Figure 6 is Figure 5 the internal block diagram of the inverter control unit.

[0149] Refer to Figure 6 , the inverter control unit 430 may include a coordinate conversion unit 310, a speed calculation unit 320, a current command generation unit 330, a voltage command generation unit 340, a coordinate conversion unit 350, and a switch control signal output unit 360.

[0150] The coordinate conversion unit 310 receives the three-phase output currents ia, ib, ic detected by the output current detection unit E and converts them into two-phase currents iα, iβ in the stationary coordinate system.

[0151] On the other hand, the coordinate conversion unit 310 may convert the two-phase currents iα, iβ in the stationary coordinate system into two-phase currents id, iq in the rotating coordinate system.

[0152] The speed calculation unit 320 may output the calculated position and the calculated speed

[0153] On the other hand, the current command generation unit 330 generates a current command value i based on the operation speed and the speed command value ω * r . For example, the current command generation unit 330 can perform PI control in the PI controller 335 based on the difference between the operation speed * q and the speed command value ω * r and generate a current command value i * q . In the drawings, although the current command value is illustrated as the q-axis current command value i * q , different from the drawings, the d-axis current command value i * d * d can also be generated together. On the other hand, the value of the d-axis current command value i * can also be set to 0.

[0154] On the other hand, the current command generation unit 330 may further include a limiter (not shown) for limiting its level to prevent the current command value i q d from exceeding the allowable range.

[0155] Next, the voltage command generation unit 340 generates d-axis and q-axis voltage command values v q * d * q * d * q q * q * q d * d * d based on the d-axis and q-axis currents i d q that are axis-converted to the two-phase rotating coordinate system in the axis conversion unit and the current command values i * d from the current command generation unit 330 and the like. For example, the voltage command generation unit 340 can perform PI control in the PI controller 344 based on the difference between the q-axis current i q and the q-axis current command value i * q and generate the q-axis voltage command value vOn the other hand, the voltage command generation unit 340 may also be provided with a limiter (not shown) for limiting its level to prevent the d-axis and q-axis voltage command values v * d and v * q from exceeding the allowable range.

[0156] On the other hand, the generated d-axis and q-axis voltage command values v * d and v * q are input to the axis conversion unit 350.

[0157] The axis conversion unit 350 receives the position calculated in the speed calculation unit 320 and the d-axis and q-axis voltage command values v * d and v * q and performs axis conversion.

[0158] First, the axis conversion unit 350 performs conversion from a two-phase rotating coordinate system to a two-phase stationary coordinate system. At this time, the position calculated in the speed calculation unit 320 can be used

[0159] Moreover, the axis conversion unit 350 performs conversion from a two-phase stationary coordinate system to a three-phase stationary coordinate system. Through this conversion, the axis conversion unit 350 outputs three-phase output voltage command values v * a, v * b, v * c.

[0160] The switch control signal output unit 360 generates and outputs a switch control signal Sic for an inverter in a pulse width modulation (PWM) method based on the three-phase output voltage command values v * a, v * b, v * c.

[0161] The output inverter switch control signal Sic can be converted into a gate drive signal in a gate drive unit (not shown) and can be input to the gates of the respective switching elements in the inverter 420. As a result, the respective switching elements Sa, S'a, Sb, S'b, Sc, S'c in the inverter 420 perform switching operations.

[0162] On the other hand, as described above, the motor drive device 100 must detect the output current io flowing in the motor, particularly the phase current, in order to perform vector control for driving the motor 230 through the control of the inverter 420.

[0163] The inverter control unit 430 can use the detected phase current and, by using the current command generation unit 330 and the voltage command generation unit 340, control the motor 230 at a desired speed and torque.

[0164] Figure 7 It is a figure Figure 4 referred to when explaining the operation of the switching device.

[0165] Referring to the accompanying drawings, Figure 7 Example (a) shows that the motor 230 operates in a Y connection as the first wiring according to the operation of the switching device 450. Figure 7 Example (b) shows that the motor 230 operates in a Δ connection as the second wiring according to the operation of the switching device 450.

[0166] The switching device 450 includes a first relay element SW1, a second relay element SW2, and a third relay element SW3 that are electrically connected to the respective phase outputs of the inverter 420.

[0167] The first end naa of the first relay element SW1, the first end nba of the second relay element SW2, and the first end nca of the third relay element SW3 are connected in parallel. One end nA of the first winding CA of the motor 230 is connected to the second end nab of the first relay element SW1. One end nB of the second winding CB of the motor 230 is connected to the second end nbb of the second relay element SW2. One end nC of the third winding CC of the motor 230 is connected to the second end ncb of the third relay element SW3. The other end na of the first winding CA of the motor 230 is connected to the common end n3 of the third relay element SW3. The other end nb of the second winding CB of the motor 230 is connected to the common end n1 of the first relay element SW1. The other end nc of the third winding CC of the motor 230 is connected to the common end n2 of the second relay element SW2.

[0168] On the other hand, the second end nab of the first relay element SW1 is connected to the u-phase output terminal ru of the inverter 420. The second end nbb of the second relay element SW2 is connected to the v-phase output terminal rv of the inverter 420. The second end ncb of the third relay element SW3 is connected to the w-phase output terminal rw of the inverter 420.

[0169] As shown in Figure 7 (a), the control unit 170 or the inverter control unit 430 can control the common ends n1, n2, n3 of the first relay element SW1, the second relay element SW2, and the third relay element SW3 to be electrically connected to the first ends naa, nba, nca of the first relay element SW1, the second relay element SW2, and the third relay element SW3 respectively to achieve the first wiring.

[0170] As a result, the output currents of the u, v, and w phases of the inverter 420 flow through the respective a-phase coils CA, b-phase coils CB, and c-phase coils CC in the motor 230 in a Y connection.

[0171] As Figure 7 As shown in (b) of [], the control unit 170 or the inverter control unit 430 can control the common terminals n1, n2, and n3 of the first relay element SW1, the second relay element SW2, and the third relay element SW3 to be electrically connected to the second terminals nab, nbb, and ncb of the first relay element SW1, the second relay element SW2, and the third relay element SW3, respectively, to achieve the second connection.

[0172] As a result, the output currents of the u, v, and w phases of the inverter 420 flow through the respective b-phase coils CB, c-phase coils CC, and a-phase coils CA in the motor 230 in a Δ connection.

[0173] As a result, the switching device 450 can control the motor 230 to be in the first connection or the second connection operation, and further, the power conversion efficiency or the driving efficiency of the motor 230 can be improved.

[0174] Figure 8a and Figure 8b is a timing diagram showing Figure 7 the winding switching operation of the switching device.

[0175] First, Figure 8a is a timing diagram showing an example of the winding switching operation of the switching device.

[0176] Referring to the drawings, when the operating frequency of the motor 230 is below f1, as Figure 7 shown in (a) of [], the switching device 450 can operate to make the motor 230 in a Y connection state.

[0177] In the figure, an example is shown where the switching device 450 operates such that the motor 230 is in a Y connection state during the P1x period until the time point Txa.

[0178] Next, during the Px period between the time points Txa and Txb, the motor 230 can stop.

[0179] Then, as Figure 7 shown in (b) of [], during the P2x period after the time point Txb, the switching device 450 can operate to make the motor 230 in a Δ connection state.

[0180] For example, when the operating frequency of the motor 230 exceeds f1, the switching device 450 operates to put the motor 230 in the Δ connection state, and the motor 230 can stop during the Px period to change from the Y connection to the Δ connection.

[0181] Next, Figure 8b FIG. is a timing chart showing another example of the winding switching operation of the switching device.

[0182] Referring to the drawings, when the operating frequency of the motor 230 is below f1, as shown in Figure 7 (b) of FIG., the switching device 450 can operate to put the motor 230 in the Y connection state.

[0183] In the figure, it is illustrated that the switching device 450 operates such that the motor 230 is in the Y connection state during the P1 period until the Ta time point.

[0184] Next, during the P2 period between the Ta time point and the Tb time point, the control unit 170 or the inverter control unit 430 can control the windings of the motor 230 to change from the first connection to the second connection.

[0185] In particular, the control unit 170 or the inverter control unit 430 can be controlled such that during the P2 period, the motor 230 does not stop, and the operating frequency of the motor 230 is temporarily decreased from the first frequency f1 to the second frequency f2.

[0186] Then, as shown in Figure 7 (b) of FIG., during the P3 period after the Tb time point, the switching device 450 can operate to put the motor 230 in the Δ connection state.

[0187] For example, the control unit 170 or the inverter control unit 430 can be controlled such that when the operating frequency of the motor 230 exceeds f1, the switching device 450 operates to put the motor 230 in the Δ connection state.

[0188] Specifically, the control unit 170 or the inverter control unit 430 can be controlled such that during the P3 period, the operating frequency of the motor 230 that has been temporarily decreased to the second frequency f2 is increased again.

[0189] The control unit 170 or the inverter control unit 430 can be controlled such that the motor 230 continues to operate without stopping during the period when the switching device 450 changes the windings of the motor 230 from the first connection to the second connection. As described above, since the motor 230 does not stop when the switching device 450 performs the switching operation, the operation efficiency of the motor 230 can be improved.

[0190] On the other hand, preferably, Figure 8b the P2 period of FIG. is longer than Figure 8aThe Px period is short. Thus, while temporarily reducing the speed of the motor 230, the windings of the motor 230 can be switched from the first connection to the second connection.

[0191] Figures 9a to 9i is a diagram Figure 4 referred to when explaining the operation of the switching device.

[0192] First, Figure 9a illustrates a case where the windings of the motor 230 are in the first connection and the operating frequency of the motor 230 is fx.

[0193] Referring to the drawings, when the output of the inverter 420 is stopped or reduced to switch to the second connection while the windings of the motor 230 are in the first connection and the operating frequency of the motor is fx, the regenerative current Irfa can flow through the switching device 450, the inverter 420, and to the dc link capacitor C.

[0194] Thus, the voltage across the dc link capacitor C, that is, the dc link voltage, can rise to Vdca1.

[0195] On the other hand, due to this regenerative current Irfa, the possibility of burnout of the dc link capacitor C is increased. In addition, due to the regenerative current Irfa, the possibility of burnout of the switching device 450, the inverter 420, etc. is also increased.

[0196] In particular, the greater the operating frequency of the motor 230, the greater the possibility of burnout of the dc link capacitor C, the switching device 450, the inverter 420, etc.

[0197] Therefore, in order to reduce the possibility of burnout of circuit elements, when the dc link voltage exceeds the allowable voltage, the braking chopper circuit 415 operates.

[0198] Figure 9b illustrates a case where the braking chopper circuit 415 operates while the windings of the motor 230 are in the first connection and the operating frequency of the motor is fx.

[0199] For example, when Figure 9a the dc link voltage Vdca1 exceeds the allowable voltage, the switching element Sp in the braking chopper circuit 415 is switched from the off state to the on state. As the switching element Sp is turned on, a part Iova of the current from the dc link capacitor C flows through the switching element Sp and the resistance element Rp in the braking chopper circuit 415.

[0200] Thus, the dc link voltage is reduced to a voltage Vdca2 smaller than Figure 9a the Vdca1.

[0201] On the other hand, as the switching element Sp is turned on, another part Ika of the current from the dc-side capacitor C flows to the inverter 420 and the switching device 450. Due to this current Ika, the possibility of burnout of the switching device 450 becomes high.

[0202] Therefore, in the present invention, a solution is proposed to Figure 9a , Figure 9b reduce the possibility of burnout of the switching device 450 by the flow of a part of the regenerative current or the dc-side current in

[0203] Figure 9c Illustrates the case where the winding of the motor 230 is in the first connection and the operating frequency of the motor 230 is f1 which is smaller than fx.

[0204] Referring to the drawings, when the winding of the motor 230 is changed from the first connection to the second connection, the control unit 170 or the inverter control unit 430 can control the operating frequency of the motor 230 to be f1 which is smaller than fx.

[0205] Thus, a regenerative current Irfa2 having a level smaller than Figure 9a Irfa can flow through the switching device 450 and the inverter 420 to the dc-side capacitor C.

[0206] On the other hand, the voltage across both ends of the dc-side capacitor C, that is, the dc-side voltage, can be Vdca3 which is smaller than Figure 9a Vdca1. At this time, preferably, Vdca3 is below the allowable voltage.

[0207] Therefore, in the operation of the switching device 450, the braking chopper circuit 415 on the dc side does not operate.

[0208] Due to this regenerative current Irfa2, the possibility of burnout of the dc-side capacitor C is significantly reduced. Further, the possibility of burnout of the switching device 450, the inverter 420, etc. is also significantly reduced.

[0209] That is, the control unit 170 or the inverter control unit 430 according to an embodiment of the present invention can control the operating frequency of the motor 230 to be below the first frequency f1 when changing from the first connection state to the second connection. Thus, it is possible to prevent burnout of the switching device 450 for changing the connection of the motor 230. In addition, it is possible to prevent burnout of the inverter 420.

[0210] Figure 9d Similar to Figure 9c illustrates the case where the winding of the motor 230 is in the first connection and the operating frequency of the motor 230 is f1 which is smaller than fx.

[0211] Referring to the accompanying drawings, when the winding of the motor 230 is changed from the first wiring to the second wiring, the control unit 170 or the inverter control unit 430 can control the operating frequency of the motor 230 to f1 which is smaller than fx.

[0212] On the other hand, different from Figure 9c is that the regenerative current does not flow at all.

[0213] Thus, the voltage across both ends of the DC-link capacitor C, that is, the DC-link voltage, can be Vdca4 which is smaller than Figure 9c Vdca3.

[0214] At this time, since Vdca4 is below the allowable voltage, in the operation of the switching device 450, the braking chopper circuit 415 at the DC side does not operate.

[0215] As a result, the possibility of burnout of the switching device 450, the inverter 420, etc. is also significantly reduced.

[0216] Next, Figure 9e An example is shown where the winding of the motor 230 is in the second wiring and the operating frequency of the motor 230 is fy.

[0217] Referring to the accompanying drawings, when the output of the inverter 420 is stopped or reduced to switch to the first wiring while the winding of the motor 230 is in the second wiring and the operating frequency of the motor is fy, the regenerative current Irfb can flow through the switching device 450 and the inverter 420 to the DC-link capacitor C.

[0218] Thus, the voltage across both ends of the DC-link capacitor C, that is, the DC-link voltage, can rise to Vdcb1.

[0219] On the other hand, due to this regenerative current Irfb, the possibility of burnout of the DC-link capacitor C is increased. In addition, due to the regenerative current Irfb, the possibility of burnout of the switching device 450, the inverter 420, etc. is also increased.

[0220] In particular, as the operating frequency of the motor 230 increases, the possibility of burnout of the DC-link capacitor C, the switching device 450, the inverter 420, etc. also increases.

[0221] Therefore, in order to reduce the possibility of burnout of circuit components, when the DC-link voltage exceeds the allowable voltage, the braking chopper circuit 415 operates.

[0222] Figure 9f An example is shown where the braking chopper circuit 415 operates while the winding of the motor 230 is in the second wiring and the operating frequency of the motor is fy.

[0223] For example, when Figure 9eWhen the DC terminal voltage Vdcb1 exceeds the allowable voltage, the switching element Sp in the braking chopper circuit 415 switches from the off state to the on state. As the switching element Sp turns on, a part Iovb of the current from the DC terminal capacitor C flows through the switching element Sp and the resistance element Rp in the braking chopper circuit 415.

[0224] Thereby, the DC terminal voltage is reduced to a voltage Vdcb2 smaller than Figure 9e Vdcb1.

[0225] On the other hand, as the switching element Sp turns on, another part Ikb of the current from the DC terminal capacitor C flows to the inverter 420 and the switching device 450. Due to this current Ikb, the possibility of burnout of the switching device 450 becomes high.

[0226] Therefore, in the present invention, a solution is proposed to reduce the possibility of burnout of the switching device 450 by Figure 9e , Figure 9f the flow of a part of the regenerative current or the DC terminal current. In particular, a control scheme is proposed such that no regenerative current is generated or the level of the regenerative current is reduced during the wiring conversion of the switching device 450, so that the DC terminal voltage does not exceed the allowable voltage.

[0227] Figure 9g An example shows the case where the winding of the motor 230 is in the second wiring and the operating frequency of the motor 230 is f2 smaller than fy.

[0228] Referring to the drawings, when the winding of the motor 230 is changed from the second wiring to the first wiring, the control unit 170 or the inverter control unit 430 can control the operating frequency of the motor 230 to be f2 smaller than fy.

[0229] Thereby, a regenerative current Irfb2 with a level smaller than Figure 9e Irfb can flow through the switching device 450 and the inverter 420 to the DC terminal capacitor C.

[0230] On the other hand, the voltage across the DC terminal capacitor C, that is, the DC terminal voltage, can be Figure 9e Vdcb3 smaller than Vdcb1. At this time, preferably, Vdcb3 is below the allowable voltage.

[0231] Therefore, during the operation of the switching device 450, the braking chopper circuit 415 at the DC terminal does not operate.

[0232] Due to this regenerative current Irfb2, the possibility of burnout of the DC terminal capacitor C is significantly reduced. Further, the possibility of burnout of the switching device 450, the inverter 420, etc. is also significantly reduced.

[0233] On the other hand, in the first connection which is Y-connected, the induced voltage or back electromotive force is approximately a multiple of that in the second connection which is Δ-connected. Therefore, preferably, the maximum operating frequency of the motor 230 in the first connection is greater than the maximum operating frequency of the motor 230 in the second connection.

[0234] Accordingly, preferably, when changing from the second connection state to the first connection, the control unit 170 or the inverter control unit 430 controls the operating frequency of the motor 230 to be equal to or less than a second frequency f2 which is smaller than the first frequency f1.

[0235] Thereby, it is possible to prevent the switching device 450 for changing the connection of the motor 230 from being burned out. In addition, it is possible to prevent the inverter 420 from being burned out.

[0236] Figure 9h Similar to Figure 9g The case where the winding of the motor 230 is in the second connection and the operating frequency of the motor 230 is f2 which is smaller than fy is illustrated.

[0237] Referring to the drawings, when the winding of the motor 230 changes from the second connection to the first connection, the control unit 170 or the inverter control unit 430 may control the operating frequency of the motor 230 to be f2 which is smaller than fy.

[0238] On the other hand, different from Figure 9g the regenerative current does not flow at all.

[0239] Thereby, the voltage across both ends of the dc-link capacitor C, that is, the dc-link voltage, may be Vdcb4 which is smaller than Figure 9g Vdcb3.

[0240] At this time, since Vdcb4 is equal to or less than the allowable voltage, the braking chopper circuit 415 at the dc-link does not operate during the operation of the switching device 450.

[0241] As a result, the possibility of burnout of the switching device 450, the inverter 420, etc. is also significantly reduced.

[0242] Figure 9i The change curve graph CV1 of the frequency in the first connection versus the dc-link voltage and the change curve graph CV2 of the frequency in the second connection versus the dc-link voltage are illustrated.

[0243] Referring to the drawings, as the operating frequency of the motor increases, the rising rate of the dc-link voltage in the first connection is greater than the rising rate of the dc-link voltage in the second connection.

[0244] On the other hand, Vdcf in the drawings may represent the allowable voltage of the dc-link voltage. Vdcf may be approximately 700V to 800V.

[0245] On the other hand, since the rate of rise of the dc terminal voltage in the first wiring is greater than that in the second wiring, when the dc terminal voltage in the first wiring exceeds the allowable voltage Vdcf like Arx, as Figure 9a and Figure 9b described, the possibility of burnout of the switching device 450 etc. increases due to the regenerative current or the dc terminal current.

[0246] Therefore, in the present invention, when changing from the first wiring to the second wiring by the operation of the switching device 450, the motor 230 is controlled to operate at a maximum frequency not exceeding the allowable voltage Vdcf, that is, at a first frequency f1 or less for the dc terminal voltage.

[0247] Similarly, in the present invention, when changing from the second wiring to the first wiring by the operation of the switching device 450, the motor 230 is controlled to operate at a maximum frequency not exceeding the allowable voltage Vdcf, that is, at a second frequency f2 or less for the dc terminal voltage. Regarding this, refer to Figure 10 described below.

[0248] Figure 10 is a flowchart showing an operation method of a motor drive device according to an embodiment of the present invention.

[0249] Referring to the drawings, the control unit 170 or the inverter control unit 430 determines whether it is necessary to change from the first wiring to the second wiring (S1010).

[0250] For example, when the motor 230 needs to operate at a speed exceeding the first speed, the control unit 170 or the inverter control unit 430 may determine that it is necessary to change from the first wiring to the second wiring.

[0251] Thereby, as Figure 9c or Figure 9d shown, the control unit 170 or the inverter control unit 430 can control the operating frequency of the motor 230 to be at a first frequency f1 or less (S1020).

[0252] Thereby, it is possible to prevent burnout of the switching device 450 for changing the wiring of the motor 230. In addition, it is possible to prevent burnout of the inverter 420.

[0253] On the other hand, when the winding of the motor 230 changes from the first wiring state to the second wiring, as Figure 9c or Figure 9d shown, the control unit 170 or the inverter control unit 430 can control the operating frequency of the motor 230 to be at a first frequency f1 or less so that the detected dc terminal voltage Vdc is below the allowable voltage. Thereby, it is possible to prevent burnout of the switching device 450 for changing the wiring of the motor 230. In addition, it is possible to prevent burnout of the inverter 420.

[0254] On the other hand, when the winding of the motor 230 changes from the first wiring state to the second wiring, as Figure 9c or Figure 9d shown, the control unit 170 or the inverter control unit 430 controls the output of the inverter 420 to stop. After the output of the inverter 420 stops, the regenerative current from the motor 230 is supplied to the dc terminal via the switching device 450 and the inverter 420, and the control unit 170 or the inverter control unit 430 can control the operating frequency of the motor 230 to be below the first frequency f1 so that the detected dc terminal voltage Vdc is below the allowable voltage during the supply of the regenerative current. Thus, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out. In addition, it is possible to prevent the inverter 420 from being burned out.

[0255] On the other hand, when the winding of the motor 230 changes from the first wiring state to the second wiring, as Figure 9c or Figure 9d shown, the control unit 170 or the inverter control unit 430 can control the operating frequency of the motor 230 to be reduced below the first frequency f1 so that the switching element Sp in the braking chopper circuit 415 is not turned on. Thus, it can be controlled that the braking chopper circuit 415 at the dc terminal does not operate during the operation of the switching device 450. As a result, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out.

[0256] On the other hand, when the winding of the motor 230 changes from the first wiring state to the second wiring, as Figure 9c or Figure 9d shown, the control unit 170 or the inverter control unit 430 can control the output of the inverter 420 to stop. After the output of the inverter 420 stops, the control unit 170 or the inverter control unit 430 can control the first regenerative current from the motor 230 to be supplied to the dc terminal, and then supply a second regenerative current lower than the first regenerative current to the dc terminal so that the switching element Sp in the braking chopper circuit 415 is not turned on. Thus, it can be controlled that the braking chopper circuit 415 at the dc terminal does not operate during the operation of the switching device 450. As a result, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out.

[0257] Next, the control unit 170 or the inverter control unit 430 can control the completion of the change from the first wiring to the second wiring (S1030). That is, it can be controlled to change from Figure 7 (a) of Figure 7 to the state of

[0258] On the other hand, the control unit 170 or the inverter control unit 430 determines whether it is necessary to change from the second wiring to the first wiring (S1040).

[0259] For example, when the motor 230 needs to operate at a speed below the first speed, the control unit 170 or the inverter control unit 430 may determine that a change from the second wiring to the first wiring is required.

[0260] Thereby, as Figure 9g or Figure 9h shown, the control unit 170 or the inverter control unit 430 may control the operating frequency of the motor 230 to be equal to or less than a second frequency f2 that is smaller than the first frequency f1 (S1050).

[0261] Thereby, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from burning out. In addition, it is possible to prevent the inverter 420 from burning out.

[0262] On the other hand, when the winding of the motor 230 changes from the second wiring state to the first wiring, as Figure 9g or Figure 9h shown, the control unit 170 or the inverter control unit 430 may control the operating frequency of the motor 230 to be equal to or less than the second frequency f2 so that the detected dc terminal voltage Vdc is equal to or less than the allowable voltage. Thereby, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from burning out. In addition, it is possible to prevent the inverter 420 from burning out.

[0263] On the other hand, when the winding of the motor 230 changes from the second wiring state to the first wiring, as Figure 9g or Figure 9h shown, the control unit 170 or the inverter control unit 430 controls the output of the inverter 420 to stop. After the output of the inverter 420 stops, the regenerative current from the motor 230 is supplied to the dc terminal via the switching device 450 and the inverter 420, and the control unit 170 or the inverter control unit 430 may control the operating frequency of the motor 230 to be equal to or less than the second frequency f2 so that the detected dc terminal voltage Vdc is equal to or less than the allowable voltage during the supply of the regenerative current. Thereby, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from burning out. In addition, it is possible to prevent the inverter 420 from burning out.

[0264] On the other hand, when the winding of the motor 230 changes from the second wiring state to the first wiring, as Figure 9g or Figure 9h shown, the control unit 170 or the inverter control unit 430 may control the operating frequency of the motor 230 to decrease to be equal to or less than the second frequency f2 so that the switching element Sp in the braking chopper circuit 415 is not turned on. Thereby, it is possible to control so that the braking chopper circuit 415 at the dc terminal does not operate during the operation of the switching device 450. As a result, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from burning out.

[0265] On the other hand, when the winding of the motor 230 changes from the second wiring state to the first wiring, as Figure 9g or Figure 9h shown, the control unit 170 or the inverter control unit 430 can control the output of the inverter 420 to stop. After the output of the inverter 420 stops, the control unit 170 or the inverter control unit 430 can control the third regenerative current to be supplied from the motor 230 to the DC terminal, and then supply a fourth regenerative current lower than the third regenerative current to the DC terminal so that the switching element Sp in the braking chopper circuit 415 is not turned on. Thus, during the operation of the switching device 450, it is possible to control the braking chopper circuit 415 at the DC terminal not to operate. As a result, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out.

[0266] Next, the control unit 170 or the inverter control unit 430 can control the completion of the change from the second wiring to the first wiring (S1060). That is, it can be controlled to change from Figure 7 in (b) to Figure 7 the state of (a).

[0267] On the other hand, when the winding of the motor 230 changes from the first wiring state to the second wiring, the control unit 170 or the inverter control unit 430 can control the operating frequency of the motor 230 to be above the first reference frequency, and when changing from the second wiring to the first wiring, the operating frequency of the motor 230 can be controlled to be above the second reference frequency.

[0268] That is, when the winding of the motor 230 changes from the first wiring state to the second wiring, the control unit 170 or the inverter control unit 430 can control the minimum operating frequency of the motor 230 to be the first reference frequency, and when changing from the second wiring to the first wiring, the minimum operating frequency of the motor 230 can be controlled to be the second reference frequency.

[0269] At this time, the first reference frequency can be greater than the second reference frequency. Or, the first reference frequency can also be the same as the second reference frequency. Regarding this, refer to Figure 11 for description.

[0270] Figure 11 is a diagram showing the operating frequency range of the motor 230 when changing from the first wiring state to the second wiring and the operating frequency range of the motor 230 when changing from the second wiring to the first wiring.

[0271] Referring to the drawings, Figure 11 in (a) illustrates the operating frequency range (f0 to f1) of the motor 230 when changing from the first wiring state to the second wiring.

[0272] Figure 11(b) illustrates the range (f0 to f2) of the operating frequency of the motor 230 when changing from the second wiring state to the first wiring.

[0273] Since the induced voltage or back electromotive force in the first wiring is greater than that in the second wiring, the control unit 170 or the inverter control unit 430 can control the range (f0 to f1) of the operating frequency of the motor 230 when the winding of the motor 230 is changed from the first wiring state to the second wiring to be larger than the range (f0 to f2) of the operating frequency of the motor 230 when changing from the second wiring to the first wiring. Thereby, burnout of the switching device 450 for changing the wiring of the motor 230 can be prevented. In addition, burnout of the inverter 420 can be prevented.

[0274] Figure 12a Illustrates the case where the operating frequency of the motor 230 when changing from the first wiring to the second wiring is the first frequency f1. Thereby, burnout of the switching device 450 for changing the wiring of the motor 230 can be prevented.

[0275] Figure 12b Illustrates the case where the operating frequency of the motor 230 when changing from the second wiring to the first wiring is the second frequency f2. Thereby, burnout of the switching device 450 for changing the wiring of the motor 230 can be prevented.

[0276] Figure 13a Illustrates the case where the braking chopper circuit 415 is like Figure 9b when operating when changing from the first wiring to the second wiring, the voltage waveform CUVa between the U and V lines, the DC terminal voltage waveform Vdca, and the phase U current waveform Iua.

[0277] For example, when the operating frequency of the motor 230 operates at fx exceeding f1 which is the maximum operating frequency, the braking chopper circuit 415 is like Figure 9b when operating.

[0278] In the interval where the switching element Sp of the braking chopper circuit 415 changes from off to on, which is the Ppa1 interval, peak components are generated in the voltage waveform CUVa between the U and V lines, the DC terminal voltage waveform Vdca, and the phase U current waveform Iua, such as Ara1, Ara2, and Ara3. Thereby, the possibility of burnout of the switching device 450 and the inverter 420 is increased.

[0279] On the other hand, in the Ppa2 interval after the Ppa1 interval, since the switching element Sp of the braking chopper circuit 415 remains in the on state, peak components are not generated in the voltage waveform CUVa between the U and V lines, the DC terminal voltage waveform Vdca, and the phase U current waveform Iua.

[0280] Figure 13b Illustrates the case where the braking chopper circuit 415 is like when changing from the first wiring to the second wiringFigure 9c or Figure 9d the UV line voltage waveform CUVb, the dc terminal voltage waveform Vdcb, and the U-phase current waveform Iub when not operating as shown in FIG. 8 or FIG. 9.

[0281] For example, when the operating frequency of the motor 230 operates at f1 which is the maximum operating frequency, the braking chopper circuit 415 does not operate as shown in FIG. 8 or FIG. 9. Figure 9c or FIG. 9.

[0282] Accordingly, different from Figure 13a in the Ppb1 interval and the Ppb2 interval, peak components do not occur in the UV line voltage waveform CUVb, the dc terminal voltage waveform Vdcb, and the U-phase current waveform Iub. Therefore, the possibility of burnout of the switching device 450 and the inverter 420 is significantly reduced.

[0283] Figure 14 is a flowchart showing an operation method of a motor drive device according to another embodiment of the present invention.

[0284] Referring to the drawings, the control unit 170 or the inverter control unit 430 determines whether it is necessary to change from the first wiring to the second wiring (S1310).

[0285] For example, when the motor 230 needs to operate at a speed exceeding the first speed, the control unit 170 or the inverter control unit 430 may determine that it is necessary to change from the first wiring to the second wiring.

[0286] Accordingly, the control unit 170 or the inverter control unit 430 can control the operating frequency of the motor 230 to be equal to or higher than the first reference frequency (S1320).

[0287] Accordingly, it is possible to prevent burnout of the switching device 450 for changing the wiring of the motor 230. In addition, it is possible to prevent burnout of the inverter 420.

[0288] Next, the control unit 170 or the inverter control unit 430 can control the completion of the change from the first wiring to the second wiring (S1330). That is, it can be controlled to change from Figure 7 the state of (a) to Figure 7 the state of (b).

[0289] On the other hand, the control unit 170 or the inverter control unit 430 determines whether it is necessary to change from the second wiring to the first wiring (S1340).

[0290] For example, when the motor 230 needs to operate at a speed equal to or lower than the first speed, the control unit 170 or the inverter control unit 430 may determine that it is necessary to change from the second wiring to the first wiring.

[0291] Accordingly, the control unit 170 or the inverter control unit 430 may control the operating frequency of the motor 230 to be equal to or higher than the second reference frequency (S1350).

[0292] On the other hand, the first reference frequency may be greater than the second reference frequency. Or, as Figure 11 shown, the first reference frequency may also be the same as the second reference frequency.

[0293] Next, the control unit 170 or the inverter control unit 430 may control the completion of the transformation from the second wiring to the first wiring (S1360). That is, it may be controlled to change from Figure 7 (b) of Figure 7 to the state of (a) of

[0294] Figure 15 is a flowchart showing an operation method of a motor driving device according to another embodiment of the present invention, Figure 16 is a diagram referred to when explaining the operation of Figure 15 .

[0295] Referring to the accompanying drawings, the control unit 170 or the inverter control unit 430 determines whether it is necessary to change from the first wiring to the second wiring (S1410).

[0296] For example, when the motor 230 needs to operate at a speed exceeding the first speed, the control unit 170 or the inverter control unit 430 may determine that it is necessary to change from the first wiring to the second wiring.

[0297] Accordingly, the control unit 170 or the inverter control unit 430 may control the temperature of the inverter 420 to be equal to or lower than the first reference temperature T1 (S1420).

[0298] Accordingly, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out. In addition, it is possible to prevent the inverter 420 from being burned out.

[0299] On the other hand, when the winding of the motor 230 changes from the first wiring state to the second wiring, the control unit 170 or the inverter control unit 430 may control the temperature of the inverter 420 to be equal to or lower than the first reference temperature T1 so that the detected dc terminal voltage Vdc is equal to or lower than the allowable voltage. Accordingly, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out. In addition, it is possible to prevent the inverter 420 from being burned out.

[0300] On the other hand, when the winding of the motor 230 changes from the first wiring state to the second wiring, as Figure 9c or Figure 9dAs shown, the control unit 170 or the inverter control unit 430 controls the output of the inverter 420 to stop. After the output of the inverter 420 stops, the regenerative current from the motor 230 is supplied to the DC terminal via the switching device 450 and the inverter 420, and the control unit 170 or the inverter control unit 430 can control the temperature of the inverter 420 to be below the first reference temperature T1 so that the detected DC terminal voltage Vdc is below the allowable voltage during the supply of the regenerative current. Thereby, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out. In addition, it is possible to prevent the inverter 420 from being burned out.

[0301] On the other hand, when the winding of the motor 230 is changed from the first wiring state to the second wiring, as Figure 9c or Figure 9d shown, the control unit 170 or the inverter control unit 430 can be controlled to be below the first reference temperature T1 so that the switching element Sp in the braking chopper circuit 415 is not turned on. Thereby, it can be controlled that the braking chopper circuit 415 at the DC terminal does not operate during the operation of the switching device 450. As a result, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out.

[0302] On the other hand, when the winding of the motor 230 is changed from the first wiring state to the second wiring, as Figure 9c or Figure 9d shown, the control unit 170 or the inverter control unit 430 can control the output of the inverter 420 to stop. After the output of the inverter 420 stops, the control unit 170 or the inverter control unit 430 can control the first regenerative current from the motor 230 to be supplied to the DC terminal, and then supply a second regenerative current lower than the first regenerative current to the DC terminal so that the switching element Sp in the braking chopper circuit 415 is not turned on. Thereby, it can be controlled that the braking chopper circuit 415 at the DC terminal does not operate during the operation of the switching device 450. As a result, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out.

[0303] Next, the control unit 170 or the inverter control unit 430 can control the end of the change from the first wiring to the second wiring (S1430). That is, it can be controlled to change from Figure 7 (a) of Figure 7 to the state of

[0304] (b).

[0305] On the other hand, the control unit 170 or the inverter control unit 430 determines whether it is necessary to change from the second wiring to the first wiring (S1440).

[0306] Accordingly, as shown in Figure 9g or Figure 9h , the control unit 170 or the inverter control unit 430 may control the temperature of the inverter 420 to be lower than a second reference temperature T2 which is lower than the first reference temperature T1 (S1450).

[0307] Accordingly, it is possible to prevent the switching device 450 for switching the wiring of the motor 230 from being burned out. In addition, it is possible to prevent the inverter 420 from being burned out.

[0308] On the other hand, when the winding of the motor 230 changes from the second wiring state to the first wiring, as shown in Figure 9g or Figure 9h , the control unit 170 or the inverter control unit 430 may control the temperature of the inverter 420 to be lower than the second reference temperature T2 so that the detected dc terminal voltage Vdc is below the allowable voltage. Accordingly, it is possible to prevent the switching device 450 for switching the wiring of the motor 230 from being burned out. In addition, it is possible to prevent the inverter 420 from being burned out.

[0309] On the other hand, when the winding of the motor 230 changes from the second wiring state to the first wiring, as shown in Figure 9g or Figure 9h , the control unit 170 or the inverter control unit 430 controls the output of the inverter 420 to stop. After the output of the inverter 420 stops, the regenerative current from the motor 230 is supplied to the dc terminal via the switching device 450 and the inverter 420, and the control unit 170 or the inverter control unit 430 may control the temperature of the inverter 420 to be lower than the second reference temperature T2 so that the detected dc terminal voltage Vdc is below the allowable voltage during the supply of the regenerative current. Accordingly, it is possible to prevent the switching device 450 for switching the wiring of the motor 230 from being burned out. In addition, it is possible to prevent the inverter 420 from being burned out.

[0310] On the other hand, when the winding of the motor 230 changes from the second wiring state to the first wiring, as shown in Figure 9g or Figure 9h , the control unit 170 or the inverter control unit 430 may control the temperature of the inverter 420 to be reduced to below the second reference temperature T2 so that the switching element Sp in the braking chopper circuit 415 is not turned on. Accordingly, it is possible to control the braking chopper circuit 415 at the dc terminal not to operate during the operation of the switching device 450. As a result, it is possible to prevent the switching device 450 for switching the wiring of the motor 230 from being burned out.

[0311] On the other hand, when the winding of the motor 230 changes from the second wiring state to the first wiring, as shown in Figure 9g or Figure 9hAs shown, the control unit 170 or the inverter control unit 430 can control the output of the inverter 420 to stop. After the output of the inverter 420 stops, the control unit 170 or the inverter control unit 430 can control the third regenerative current to be supplied from the motor 230 to the DC terminal, and then supply a fourth regenerative current lower than the third regenerative current to the DC terminal so that the switching element Sp in the braking chopper circuit 415 is not turned on. Thus, it can be controlled that the braking chopper circuit 415 at the DC terminal does not operate during the operation of the switching device 450. As a result, it is possible to prevent the switching device 450 for changing the wiring of the motor 230 from being burned out.

[0312] Next, the control unit 170 or the inverter control unit 430 can control the completion of the transformation from the second wiring to the first wiring (S1460). That is, it can be controlled to change from Figure 7 in (b) to Figure 7 the state of (a).

[0313] On the other hand, when the winding of the motor 230 is transformed from the first wiring state to the second wiring, the control unit 170 or the inverter control unit 430 can control the temperature of the inverter 420 to be above the first minimum temperature, and when transforming from the second wiring to the first wiring, the temperature of the inverter 420 can be controlled to be above the second minimum temperature.

[0314] At this time, the first minimum temperature can be greater than the second minimum temperature. Or, the first minimum temperature can also be the same as the second minimum temperature. Regarding this, refer to Figure 16 for description.

[0315] Figure 16 is a diagram showing the range of the operable temperature of the inverter 420 when transforming from the first wiring state to the second wiring and the range of the operable temperature of the inverter 420 when transforming from the second wiring to the first wiring.

[0316] Referring to the drawings, Figure 16 (a) of shows the range of the operable temperature of the inverter 420 (T0 to T1) when transforming from the first wiring state to the second wiring.

[0317] Figure 16 (b) of shows the range of the operable temperature of the inverter 420 (T0 to T2) when transforming from the second wiring state to the first wiring.

[0318] Since the induced voltage or back electromotive force in the first wiring is greater than that in the second wiring, the control unit 170 or the inverter control unit 430 can control the operable temperature range (T0 to T1) of the inverter 420 when the winding of the motor 230 is changed from the first wiring state to the second wiring to be larger than the operable temperature range (T0 to T2) of the inverter 420 when changing from the second wiring to the first wiring. Thereby, burnout of the switching device 450 for changing the wiring of the motor 230 can be prevented. In addition, burnout of the inverter 420 can be prevented.

[0319] On the other hand, in addition to Figure 1 the air conditioner 100 of Figures 4 to 16 the motor drive device 220 of the embodiment of the present invention described in

[0320] can also be applied to various household appliances. For example, it can be applied to various fields such as laundry treatment equipment (washing machines, dryers, etc.), refrigerators, water purifiers, floor cleaning robots, robots, vehicles, drones, etc.

[0321] Moreover, the preferred embodiments of the present invention have been illustrated and described above. However, the present invention is not limited to the specific embodiments described above. Within the scope not departing from the technical idea of the present invention, those of ordinary skill in the technical field to which the present invention pertains can perform various modifications, and such modified implementations should not be understood separately without departing from the technical idea or prospect of the present invention.

Claims

1. A motor drive device, characterized in that, comprising: an inverter provided with a plurality of switching elements, which outputs an AC power supply to the motor based on switching operations; a switching device disposed between the inverter and the motor, which transforms the windings of the motor into a first wiring or a second wiring; a control unit for controlling the inverter and the switching device; and a temperature detection unit attached to the inverter for detecting the temperature of the inverter, wherein the first wiring is a Y wiring and the second wiring is a Δ wiring, when the windings of the motor are transformed from the first wiring state to the second wiring, the control unit controls the operating frequency of the motor to be below a first frequency, and the control unit controls the temperature of the inverter to be below a first reference temperature. When transformed from the second wiring to the first wiring, the control unit controls the operating frequency of the motor to be below a second frequency lower than the first frequency, and the control unit controls the temperature of the inverter to be below a second reference temperature higher than the first reference temperature.

2. The motor drive device according to claim 1, characterized in that, further comprising: a DC-link capacitor for storing a DC-link voltage; a DC-link voltage detection unit for detecting the DC-link voltage; and a braking chopper circuit connected to both ends of the DC-link capacitor and including a resistance element and a switching element.

3. The motor drive device according to claim 2, characterized in that, when the windings of the motor are transformed from the first wiring state to the second wiring, the control unit controls the operating frequency of the motor to be below the first frequency so that the detected DC-link voltage is below an allowable voltage.

4. The motor drive device according to claim 2, characterized in that, when the windings of the motor are transformed from the first wiring state to the second wiring, the control unit controls the output of the inverter to stop. After the output of the inverter stops, the regenerative current from the motor is supplied to the DC-link via the switching device and the inverter, and the control unit controls the operating frequency of the motor to be below the first frequency so that the detected DC-link voltage is below the allowable voltage during the supply of the regenerative current.

5. The motor drive device according to claim 2, characterized in that, when the windings of the motor are transformed from the first wiring state to the second wiring, the control unit controls the output of the inverter to stop. After the output of the inverter stops, the control unit controls a first regenerative current from the motor to be supplied to the DC-link, and then a second regenerative current lower than the first regenerative current is supplied to the DC-link so that the switching element in the braking chopper circuit is not turned on.

6. The motor drive device according to claim 2, characterized in that, When the winding of the motor changes from the second wiring state to the first wiring, the control unit controls the output of the inverter to stop. After the output of the inverter stops, the regenerative current from the motor is supplied to the DC terminal via the switching device and the inverter, and the control unit controls the operating frequency of the motor to be equal to or lower than the second frequency so that the detected DC terminal voltage is equal to or lower than the allowable voltage during the supply of the regenerative current.

7. The motor drive device according to claim 2, wherein, when the winding of the motor changes from the second wiring state to the first wiring, the control unit controls the output of the inverter to stop. After the output of the inverter stops, the control unit controls the third regenerative current from the motor to be supplied to the DC terminal, and then supplies a fourth regenerative current lower than the third regenerative current to the DC terminal so that the switching element in the braking chopper circuit is not turned on.

8. The motor drive device according to claim 1, wherein, when the winding of the motor changes from the first wiring state to the second wiring, the control unit controls the operating frequency of the motor to be equal to or higher than the first reference frequency, and when changing from the second wiring to the first wiring, the control unit controls the operating frequency of the motor to be equal to or higher than the second reference frequency.

9. An air conditioner, wherein, it includes the motor drive device according to any one of claims 1 to 8.

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