JP6775548B2 - Motor control device and air conditioner - Google Patents

Description

The present invention relates to a motor control device and an air conditioner.

When the motor driven by the power converter is stopped, a reverse torque may be generated due to the characteristics of the load connected to the motor, and the motor may reverse. When the motor reverses, problems such as abnormal wear and abnormal noise occur.

As a means for suppressing reverse rotation without adding an external brake circuit or the like, for example, there is a technique described in Patent Document 1. In Patent Document 1, all the switching elements of each phase of either the upper arm or the lower arm are turned on, the terminals of each phase of the motor are short-circuited to generate a brake current, and the switching element is turned on and off. A means for limiting the brake current flowing through the motor by control to a predetermined current limit value is described.

Japanese Unexamined Patent Publication No. 2014-57391

However, since the means described in Patent Document 1 are premised on having an alternating current detecting means for detecting the alternating current flowing through the motor, there is no description about a device not having the alternating current detecting means. Further, as a means for limiting the brake current to a predetermined current limit value, only a method of temporarily stopping the brake is described, and there is no description of a means for reducing the on-duty of the switching element.
Therefore, an object of the present invention is to provide a highly reliable motor control device and an air conditioner using this motor control device.

In order to solve the above-mentioned problems, the motor control device of the present invention includes a first switching element group including a plurality of switching elements connected to the positive electrode of the DC power supply, and a plurality of switchings connected to the negative electrode of the DC power supply. A power conversion circuit including a second switching element group composed of elements and converting DC power into AC power to drive an electric motor, a DC current detecting means for detecting a current flowing on the DC side of the power conversion circuit, and the above-mentioned A drive signal for driving the power conversion circuit is output, and when the electric motor is stopped, a drive signal for switching one of the first or second switching element groups with a predetermined duty is output. When the current value detected by the DC current detecting means exceeds a predetermined set value, the duty control mode for reducing the duty is executed until the first predetermined time elapses, and then the motor current is intermittently detected. It is characterized by including a controller that executes an intermittent current detection mode until a second predetermined time elapses .
Other means will be described in the form for carrying out the invention.

According to the present invention, it is possible to provide a highly reliable motor control device and an air conditioner using this motor control device.

It is a block diagram of the motor control device in this embodiment. It is a figure which shows the reverse rotation suppression operation of a motor by a motor control device. It is a graph which shows the current which flows in each phase. It is a graph which shows the current flowing through each phase and the shunt current. It is a figure which shows the switching state and the current path which turned on the lower arm in region 1. It is a figure which shows the switching state and the current path which turned off the lower arm in region 1. It is a figure which shows the switching state and the current path which turned on the lower arm in region 2. It is a figure which shows the switching state and the current path which turned off the lower arm in region 2. It is a figure which shows the switching state and the current path which turned on the lower arm in region 3. It is a figure which shows the switching state and the current path which turned off the lower arm in region 3. It is a conceptual diagram of the brake control of this embodiment. It is a flowchart which shows the brake control of this embodiment. It is a conceptual diagram of an intermittent current detection mode. It is a conceptual diagram of the means for increasing the equivalent on-duty while performing current detection. It is a conceptual diagram of another means for increasing the equivalent on-duty while performing current detection. It is an external view of the air conditioner using the motor control device of this embodiment. It is a block diagram which shows the structure of an air conditioner.

Hereinafter, a mode for carrying out the present invention will be described in detail with reference to each figure.
FIG. 1 is a configuration diagram of the motor control device 1 according to the present embodiment.
The motor control device 1 includes a smoothing capacitor 4 that smoothes direct current, an inverter module 5 that converts direct current into alternating current to drive a compressor motor 6, and a shunt resistor R that detects a power supply current flowing through the inverter module 5. A controller 2 for controlling the inverter module 5 is provided. The controller 2 has, for example, a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an A / D converter. This microcomputer controls the impactor module 5 by executing a control program stored in the ROM. The motor control device 1 is connected to the UVW phase of the compressor motor 6 and rotationally drives the compressor motor 6.

The inverter module 5 is a power conversion circuit in which six switching elements 53 to 58 are connected by a three-phase bridge. The upper arm 51 includes switching elements 53, 55, 57 connected to a positive electrode node P of a DC power supply (not shown). The lower arm 52 includes switching elements 54, 56, 58 connected to a negative electrode node N of a DC power supply (not shown). These switching elements 53 to 58 include a freewheeling diode and allow a current to flow from the source to the drain.

The switching elements 53 and 54 are connected in series to form a U-phase switching leg. The drain of the switching element 53 is connected to the positive electrode node P of the DC power supply. The source of the switching element 53 is connected to the drain of the switching element 54, and further connected to one end of the coil Lu of the compressor motor 6. The source of the switching element 54 is connected to the negative electrode node N of the DC power supply.

The switching elements 55 and 56 are connected in series to form a V-phase switching leg. The drain of the switching element 55 is connected to the positive electrode node P of the DC power supply. The source of the switching element 55 is connected to the drain of the switching element 56, and further connected to one end of the coil Lv of the compressor motor 6. The source of the switching element 56 is connected to the negative electrode node N of the DC power supply.

The switching elements 57 and 58 are connected in series to form a W-phase switching leg. The drain of the switching element 57 is connected to the positive electrode node P of the DC power supply. The source of the switching element 57 is connected to the drain of the switching element 58, and further connected to one end of the coil Lw of the compressor motor 6. The source of the switching element 58 is connected to the negative electrode node N of the DC power supply.

The DC voltage supplied by the DC power supply (not shown) is smoothed by the smoothing capacitor 4 connected between the positive electrode node P and the negative electrode node N, and is applied to the inverter module 5. The inverter module 5, which is a DC / AC converter, is controlled by the controller 2 (microcomputer), and a pseudo three-phase AC voltage is output. A current flows through the compressor motor 6 by this three-phase AC voltage to drive the compressor motor 6.

The current flowing through the compressor motor 6 is detected by the shunt resistor R as a direct current flowing through the switching elements 53 to 58. This DC current is detected as the voltage across the shunt resistor R, and is taken into the controller 2 by, for example, an A / D converter (not shown) and monitored. The shunt resistor R and the A / D converter function as a direct current detecting means for detecting the current flowing on the direct current side of the inverter module 5.

The controller 2 outputs a drive signal to the control terminals of the six switching elements 53 to 58 to control the inverter module 5. The compressor motor 6 rotates the rotor 62 by passing a three-phase alternating current through the Y-connected coils Lu, Lv, and Lw.

FIG. 2 is a diagram showing a reverse rotation suppression operation of the motor by the motor control device 1.
As a means for suppressing reverse rotation without adding an external brake circuit or the like, there is a means for turning on all phases of the lower arm 52 of the inverter module 5 and short-circuiting each phase in this way. That is, the controller 2 has the switching elements 54, 56, and 58 turned on. A current flows from the coil Lw toward the coils Lu and Lv according to the induced voltage generated by the reversal of the compressor motor 6.

The current flowing from the coil Lu toward the inverter module 5 returns to the coil Lw again via the switching element 54 and the switching element 58. The current flowing from the coil Lv toward the inverter module 5 returns to the coil Lw again via the switching element 56 and the switching element 58. As a result, a brake torque is generated in the compressor motor 6.

As shown in FIG. 3, the current flowing through each phase at this time sequentially changes in current polarity according to the rotation angle position of the rotor.

FIG. 3 is a graph showing the current flowing through each phase when the rotor is rotating. Regions # 1 to # 6 are for explaining how the current flows at each time.
The U-phase current Iu, the V-phase current Iv, and the W-phase current Iw are sine waves whose phases are shifted by 120 degrees.
In region # 1, the W-phase current Iw is a positive current. Here, the positive current means the current flowing from the inverter module 5 toward the compressor motor 6. Further, the U-phase current Iu and the V-phase current Iv are negative currents. The negative current means the current flowing from the compressor motor 6 toward the inverter module 5.

In region # 2, a negative current flows in the U phase. Further, a positive current flows through the V phase and the W phase. In region # 3, a positive current flows through the V phase. Further, a negative current flows between the W phase and the U phase.

In region # 4, a negative current flows in the W phase. Further, a positive current flows through the V phase and the U phase. In region # 5, a positive current flows through the U phase. Further, a negative current flows between the V phase and the W phase. In region # 6, a negative current flows in the V phase. Further, a positive current flows through the W phase and the U phase.

When the on-duty of the lower arm 52 is set to 100% and kept on, no current flows through the shunt resistor R. However, when the on-duty of the lower arm 52 is less than 100%, the shunt current Ish flows through the shunt resistor R while the lower arm 52 is off.

FIG. 4 is a graph showing the current flowing through each phase and the shunt current Ish.
Here, in the regions # 1 to # 3 shown in FIG. 3, the relationship between each phase motor current and the shunt current Ish when the on-duty is less than 100% is shown.
In region # 1, the shunt current Ish is the sum of the U-phase current Iu and the V-phase current Iv when the lower arm 52 is off, and is 0A when the lower arm 52 is on.
In region # 2, the shunt current Ish is equal to the U-phase current Iu when the lower arm 52 is off and 0A when the lower arm 52 is on.
In region 3, the shunt current Ish is the sum of the W-phase current Iw and the U-phase current Iu when the lower arm 52 is off, and is 0A when the lower arm 52 is on.

5A to 5F are diagrams showing switching states and current paths when each phase is turned on and off in the same regions # 1 to # 3. By turning on and off all phases at the same time in this way, the current flowing through the motor can be detected from the current flowing through the shunt resistor R. Although the current sharing of each phase is unknown, the maximum current can be detected, so that it is a sufficiently effective current detecting means from the viewpoint of protecting the switching element.

FIG. 5A is a diagram showing a switching state and a current path in which the lower arm 52 is turned on in region # 1.
At this time, a current flows from the inverter module 5 to the W-phase coil Lw. This current flows through the U-phase coil Lu and the switching element 54, and also flows through the V-phase coil Lv and the switching element 56, and returns to the W-phase coil Lw again via the switching element 58.

FIG. 5B is a diagram showing a switching state and a current path in which the lower arm 52 is turned off in region # 1.
At this time as well, a current flows from the inverter module 5 to the W-phase coil Lw. This current flows through the U-phase coil Lu and the freewheeling diode of the switching element 53, and also flows through the V-phase coil Lv and the freewheeling diode of the switching element 55, and flows through the smoothing capacitor 4, the shunt resistor R, and the freezing diode of the switching element 58. The coil Lw of the W phase is returned to the coil Lw again.
Since the shunt resistor R is provided with a period during which the current flows in this way, the controller 2 can detect the motor current. As a result, the maximum current during brake control can be controlled, and the reliability of the power module can be ensured. The start timing of brake control and the duty increase rate can be easily determined. Further, the brake can be started immediately after the inverter is stopped to shorten the reverse rotation time.

FIG. 5C is a diagram showing a switching state and a current path in which the lower arm 52 is turned on in region # 2.
At this time, a current flows from the U-phase coil Lu toward the inverter module 5. This current flows through the switching element 54, then returns to the coil Lu via the switching element 56 and the coil Lv, and further returns to the coil Lu via the switching element 58 and the coil Lw.

FIG. 5D is a diagram showing a switching state and a current path in which the lower arm 52 is turned off in region # 2.
At this time as well, a current flows from the U-phase coil Lu toward the inverter module 5. This current flows through the freewheeling diode of the switching element 53, the smoothing capacitor 4, and the shunt resistor R, then returns to the coil Lu via the freewheeling diode of the switching element 56 and the coil Lv, and further returns to the freewheeling diode and the coil of the switching element 58. It returns to the coil Lu via Lw.
In this way, since the shunt resistor R is provided with a period during which the current flows, the controller 2 can detect the motor current.

FIG. 5E is a diagram showing a switching state and a current path in which the lower arm 52 is turned on in region # 3.
At this time, a current flows from the inverter module 5 to the V-phase coil Lv. This current flows through the U-phase coil Lu and the switching element 54, and also flows through the W-phase coil Lw and the switching element 58, and returns to the V-phase coil Lv again via the switching element 56.

FIG. 5F is a diagram showing a switching state and a current path in which the lower arm 52 is turned off in region # 3.
At this time as well, a current flows from the inverter module 5 to the V-phase coil Lv. This current flows through the U-phase coil Lu and the freewheeling diode of the switching element 53, and also flows through the W-phase coil Lw and the freewheeling diode of the switching element 57, and flows through the smoothing capacitor 4, the shunt resistor R, and the freewheeling diode of the switching element 56. It returns to the V-phase coil Lv again via.
In this way, since the shunt resistor R is provided with a period during which the current flows, the controller 2 can detect the motor current.

It should be noted that it is not limited to turning on / off the lower arm 52 while turning off all phases of the upper arm 51 as shown in FIGS. 5A to 5F, and the upper arm 51 may be turned on / off while turning off all phases of the lower arm 52. , Not limited.

FIG. 6 is a conceptual diagram of the brake control of the present embodiment.
The duty control mode is set until the time t13 elapses after the start of the brake control. In the duty control mode, the controller 2 limits the on-duty to x% (x% is 0% or more and less than 100%), and lowers the on-duty when the detected shunt current Ish exceeds a predetermined value. Therefore, the motor control device 1 can start the brake control immediately after the motor is stopped. Then, the maximum reverse rotation speed of the compressor motor 6 can be reduced. Here, x% of the on-duty is set to a value at which the motor current can be detected by the shunt resistor R.

The compressor motor 6 rotates normally until the time t11 elapses after the brake control starts, and reverses from the time t11 to the time t15.

After the time t13 elapses, the intermittent current detection mode of FIG. 8 is performed until the time t14 elapses. By operating in the intermittent current detection mode, the controller 2 can maximize the on-duty while detecting the motor current.

After the time t14 elapses, the entire on period is until the time t16 elapses. The controller 2 turns on all phases of the lower arm 52. By controlling in this way, the total number of reverse rotations can be reduced, abnormal wear and abnormal noise can be reduced, and highly reliable brake control can be realized.

FIG. 7 is a flowchart showing the brake control of the present embodiment.
The microcomputer of the controller 2 performs this brake control by executing a program stored in the ROM. When the brake control is started, the controller 2 turns off all phases of the upper arm 51 and PWM-controls the lower arm 52 (S10). The following steps S10 to S15 correspond to the duty control mode shown in FIG.

The controller 2 determines whether or not the shunt current Ish is equal to or greater than the set value (S11). Since the shunt current Ish is equal to the motor current, the controller 2 determines whether or not the motor current is equal to or greater than the set value. In step S11, if the shunt current Ish is equal to or greater than the set value, the controller 2 reduces the on-duty of the lower arm 52 (S12) and proceeds to the process of step S15. At this time, the controller 2 performs integral control. If the shunt current Ish is less than the set value, the controller 2 proceeds to the process of step S13.

In step S13, the controller 2 determines whether or not the on-duty of the lower arm 52 is equal to or less than the current-detectable value (x%). If the on-duty is equal to or less than the current-detectable value, the controller 2 linearly increases the on-duty (S14) and proceeds to the process of step S15. If the on-duty exceeds the current-detectable value, the controller 2 proceeds to the process of step S15.

In step S15, the controller 2 determines whether or not the time t13 has elapsed. If the time t13 has not elapsed, the controller 2 returns to the process of step S10, and if the time t13 has elapsed, the controller 2 proceeds to the process of step S16.

Steps S16 to S19 correspond to an intermittent current detection mode (see FIG. 6) in which 100% and x% (for example, 93%) of the on-duty of the lower arm 52 are alternately set to intermittently detect the motor current. ..
In step S16, the controller 2 turns on all phases of the lower arm 52 over the first period. After that, the controller 2 PWM-controls the lower arm 52 with a predetermined value of on-duty over the second period (S17), and linearly increases the first period (S18). As a result, the brake torque can be maximized. The first period corresponds to the period P1a shown in FIG. 8 and the periods P1c to P1f shown in FIG. The second period corresponds to the period P2 shown in FIGS. 8 and 9.

In step S19, the controller 2 determines whether or not the time t14 has elapsed. If the time t14 has not elapsed, the controller 2 returns to the process of step S16, and if the time t14 has elapsed, the controller 2 proceeds to the process of step S20.

In step S20, the controller 2 turns on all phases of the lower arm 52 until time t16 has elapsed. Step S20 corresponds to the entire on-period shown in FIG. After that, the controller 2 turns off all phases of the lower arm 52, and then ends the brake control shown in FIG. 7.

FIG. 8 is a conceptual diagram of the intermittent current detection mode.
In the duty control mode before the time t13, the controller 2 detects the shunt current Ish at least once in each cycle of the PWM carrier. The minimum pulse width for detecting the shunt current Ish is defined by the characteristics of the A / D converter of the microcomputer and the switching elements 53 to 58. As a result, the maximum value of on-duty is determined. Therefore, in the intermittent current detection mode after the time t13, the controller 2 thins out the current detection for each cycle of the PWM carrier, detects the shunt current Ish only in the PWM carrier cycle of the period P2, and detects the shunt current Ish in the other periods P1a and P1b. Sets the on-duty to 100%.

FIG. 9 is a conceptual diagram of means for increasing the equivalent on-duty while detecting the current.
The period P2 (second period) is a period during which the controller 2 performs PWM control. By turning off the drive signal of the lower arm 52 in this way, the shunt current Ish can be passed through the shunt resistor R, and the shunt current Ish can be detected.

On the other hand, the periods P1c to P1f (first period) are periods in which the controller 2 sets the on-duty to 100%. The controller 2 causes the periods P1c to P1f to appear more than the period P2 according to the passage of time. As a result, the controller 2 increases the ratio of PWM control thinning out.

The controller 2 can increase the equivalent on-duty and detect the motor current by increasing the ratio of PWM control thinning out. As the number of thinning out of current detection increases, the ratio of on-duty to 100% also increases, and the equivalent on-duty is increased, so that the braking force can be increased. Since the motor rotation speed is gradually slowed down, on-duty adjustment is possible even with intermittent current detection. As a result, the total number of reversals shown in FIG. 6 can be reduced.
The integrated gain of on-duty control is also increased according to the number of thinning out.

FIG. 10 is a conceptual diagram of another means for increasing the equivalent on-duty while performing current detection.
In this way, it is possible to detect the motor current while increasing the equivalent on-duty by lengthening the control cycle of the PWM carrier according to the passage of time. As a result, the total number of reversals shown in FIG. 6 can be reduced.

FIG. 11 is an external view of the air conditioner 7 using the motor control device 1 of the present embodiment.
As shown in FIG. 11, the air conditioner 7 includes an indoor unit 71, an outdoor unit 72, and a remote controller Re. The indoor unit 71 and the outdoor unit 72 are connected by a refrigerant pipe 73, and the room in which the indoor unit 71 is installed is air-conditioned by a well-known refrigerant cycle. Further, the indoor unit 71 and the outdoor unit 72 transmit and receive information from each other via a communication cable (not shown).

The remote controller Re is operated by the user to transmit an infrared signal to the indoor unit 71. The contents of this infrared signal are commands such as an operation request, a change of a set temperature, a timer, a change of an operation mode, and a stop request. The air conditioner 7 performs air conditioning operation such as a cooling mode, a heating mode, and a dehumidifying mode based on the commands of these infrared signals. Further, the indoor unit 71 transmits data such as room temperature information, humidity information, and electricity bill information to the remote controller Re.
FIG. 12 is a block diagram showing the configuration of the air conditioner 7.
In the air conditioner 7, the compressor 61, the indoor heat exchanger 79, the indoor expansion valve 74, the outdoor heat exchanger 78, and the accumulator 76 are sequentially connected to circulate the refrigerant to form a refrigeration cycle. When the room is cooled, the refrigerant compressed by the compressor 61 is condensed and liquefied by the outdoor heat exchanger 78, depressurized by the indoor expansion valve 74, and evaporated by the indoor heat exchanger 79 to be evaporated by the compressor 61. Return to. The electric motor 75 for the indoor blower promotes the heat exchange of the indoor unit 71, and the electric motor 77 for the outdoor blower promotes the heat exchange of the outdoor unit 72.

The compressor 61 is driven by a compressor motor 6 whose operating frequency is variably controlled in relation to the capacity required for the refrigeration cycle, and the operating frequency is controlled by the motor control device 1 shown in FIG.
In the refrigeration cycle, the opening degree of the indoor expansion valve 74 or the outdoor expansion valve (not shown) that adjusts the refrigerant flow rate in addition to the rotation speed of the compressor 61, the rotation speed of the electric motor 75 for the indoor blower and the electric motor 77 for the outdoor blower, A four-way valve (not shown) that switches the cooling / heating operation mode is controlled. As information for that, the operation command signal by the remote control Re that sets the operation mode and temperature, the temperature of each part (compressor 61 discharge gas temperature, outside air temperature, heat exchanger temperature, evaporation temperature, suction temperature, blowout temperature, freezing temperature) , Gas pipe temperature, etc.) and pressure (suction pressure, discharge pressure of the compressor 61) are detected and the like are input to the control unit (not shown) of the air exchanger 7.

The detection signal and the command signal input to the control unit (not shown) are input to the controller 2. From this, the refrigeration cycle control can be performed by the motor control device 1 or the like, and various control mechanisms (outdoor expansion valve, electric motor 77 for outdoor blower, four-way valve for switching the operation mode of cooling / heating) can be controlled. As a result, abnormal wear and abnormal noise in the brake control of the compressor motor 6 mounted on the compressor 61 can be reduced, and highly reliable brake control can be realized.

<< Modification example >>
The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. It is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is also possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

Each of the above configurations, functions, processing units, processing means, and the like may be partially or wholly realized by hardware such as an integrated circuit. Each of the above configurations, functions, and the like may be realized by software by the processor interpreting and executing a program that realizes each function. Information such as programs, tables, and files that realize each function can be placed in a memory, hard disk, recording device such as SSD (Solid State Drive), or recording medium such as flash memory card or DVD (Digital Versatile Disk). it can.

In each embodiment, the control lines and information lines indicate what is considered necessary for explanation, and the product does not necessarily indicate all the control lines and information lines. In practice, it can be considered that almost all configurations are interconnected.

1 Motor controller 2 Controller 4 Smoothing capacitor 5 Inverter module (power conversion circuit)
51 Upper arm (first switching element group)
52 Lower arm (second switching element group)
53 to 58 Switching element 6 Compressor motor 7 Air conditioner 71 Indoor unit 72 Outdoor unit 73 Refrigerant piping 74 Indoor expansion valve (expansion valve)
75 Electric motor for indoor blower 76 Accumulator (condenser)
77 Electric motor for outdoor blower 78 Outdoor heat exchanger (evaporator)
79 Indoor heat exchanger (evaporator)
Re remote control R shunt resistor (DC current detecting means)

Claims (8)

A first switching element group composed of a plurality of switching elements connected to the positive side of the DC power supply and a second switching element group composed of a plurality of switching elements connected to the negative side of the DC power supply are provided, and DC power is exchanged. A power conversion circuit that converts electricity into electric power to drive an electric motor,
A DC current detecting means for detecting the current flowing on the DC side of the power conversion circuit, and
A drive signal for driving the power conversion circuit is output, and a drive signal for switching one of the first or second switching element groups with a predetermined duty is output when the electric motor is stopped. When the current value detected by the DC current detecting means exceeds a predetermined set value, the duty control mode for reducing the duty is executed until the first predetermined time elapses, and then the motor current is intermittently detected. A controller that executes the intermittent current detection mode until the second predetermined time elapses ,
A motor control device characterized by comprising. In the intermittent current detection mode, the controller detects the motor current by intermittently turning off one of the first or second switching element groups.
The motor control device according to claim 1. After executing the intermittent current detection mode, the controller turns on one of the first or second switching element groups.
The motor control device according to claim 1 or 2. In the duty control mode, the controller limits the duty to a predetermined value at which the DC current detecting means can detect a current flowing on the DC side of the power conversion circuit.
The motor control device according to claim 1. In the intermittent current detection mode, the controller generates a drive signal by PWM control and lengthens the control cycle of PWM control according to the passage of time.
The motor control device according to any one of claims 1 to 4, wherein the motor control device is characterized. In the intermittent current detection mode, the controller generates a drive signal by PWM control, outputs a drive signal that turns on the switching element group over one cycle of the PWM control cycle, and PWM control. It has a second period for outputting a drive signal that turns off the switching element group during the cycle, and causes the first period to appear more than the second period with the passage of time.
The motor control device according to any one of claims 1 to 5, wherein the motor control device is characterized. The controller generates a drive signal by PWM control when the electric motor is stopped, and outputs a drive signal that turns off the switching element group at a predetermined timing during the PWM control cycle.
The motor control device according to any one of claims 1 to 5 . The motor control device according to any one of claims 1 to 7 is provided, and the motor control device is provided.
An air conditioner including a refrigerant circuit including a compressor driven by the electric motor, a condenser, an expansion valve, and an evaporator.

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