Motor drive device, air conditioner, motor drive method, and motor drive program

Abstract

The present invention provides a motor drive device, an air conditioner, a motor drive method, and a motor drive program that can reduce the chance of a changeover switch being damaged when a motor is driven and reduce the chance of a motor drive device malfunctioning. A motor drive device (20) comprises: a drive circuit (23) which is provided in correspondence with a plurality of motors (22) and which drives the motors (22) alternatively; a changeover switch (25) disposed between a power supply (24) and the plurality of motors to change the motor (22) connected to the power supply (24); and a controller (21) that selects a motor (22) to be controlled from among the plurality of motors (22), outputs to the changeover switch a changeover control signal for connecting the motor (22) under control and the power supply (24), and outputs, to a drive circuit, a drive control signal for driving the motor (22) under control, wherein the changeover switch (25) is configured to be capable of carrying electrical currents bidirectionally.

Description

Motor drive device, air conditioner, motor drive method, and motor drive program

[0001] The present disclosure relates to a motor drive device, an air conditioner, a motor drive method, and a motor drive program.

[0002] One example of a motor drive device configuration is one in which multiple motors to be driven are controlled by a number of drive circuits that is fewer than the number of motors. This configuration prevents an increase in the number of component elements mounted on the motor drive device and the number of controller ports required for motor control, thereby suppressing an increase in motor control costs. For example, Patent Document 1 discloses a circuit in which a single drive circuit drives a motor and switches the motor to be driven using multiple transistors.

[0003] Japanese Patent Application Publication No. 5-276794

[0004] However, in the circuit configuration disclosed in Patent Document 1, there is a possibility that the transistor may be damaged by reverse current or overvoltage that occurs when the motor to be driven is in operation. In the worst case scenario, the transistor may fail and become unable to function as a motor drive device.

[0005] The present disclosure has been made in consideration of these circumstances, and aims to provide a motor drive device, an air conditioner, a motor drive method, and a motor drive program that reduce the possibility of damage to the selector switch when the motor is driven and reduce the possibility of the motor drive device failing.

[0006] In order to solve the above problems, the motor drive device, air conditioner, motor drive method, and motor drive program disclosed herein employ the following means: The motor drive device disclosed herein includes a drive circuit provided for a plurality of motors and selectively driving the motors, a changeover switch disposed between a power source and the plurality of motors and switching between the motors connected to the power source, and a controller that selects a motor to be controlled from the plurality of motors and outputs a changeover control signal to the changeover switch for connecting the motor to be controlled to the power source, and outputs a drive control signal to the drive circuit for driving the motor to be controlled, the changeover switch being configured to allow current to flow in both directions.

[0007] The air conditioner of the present disclosure includes a refrigerant circuit having a compressor that compresses a refrigerant, a condenser that condenses the compressed refrigerant, an expansion valve that expands the condensed refrigerant, and an evaporator that evaporates the expanded refrigerant, and a plurality of motors controlled by the motor drive device.

[0008] The motor driving method disclosed herein comprises the steps of: selectively driving a plurality of motors using drive circuits provided corresponding to the motors; switching the motor connected to the power source using a changeover switch arranged between a power source and the plurality of motors and configured to allow current to flow in both directions; selecting a motor to be controlled from the plurality of motors, outputting a changeover control signal to the changeover switch for connecting the motor to be controlled to the power source, and outputting a drive control signal to the drive circuit for driving the motor to be controlled.

[0009] The motor driving program of the present disclosure causes a computer to execute the following processes: a process of selectively driving a plurality of motors using a driving circuit provided corresponding to the plurality of motors; a process of switching the motor connected to the power source using a changeover switch arranged between a power source and the plurality of motors and configured to allow current to flow in both directions; a process of selecting a motor to be controlled from the plurality of motors, outputting a changeover control signal to the changeover switch for connecting the motor to be controlled to the power source, and outputting a drive control signal to the driving circuit for driving the motor to be controlled.

[0010] According to the present disclosure, it is possible to reduce the possibility of the changeover switch being damaged when the motor is driven, and to reduce the possibility of the motor drive device breaking down.

[0011] 1 is a schematic diagram showing a part of the configuration of an air conditioner in the present disclosure; FIG. 2 is a diagram showing an example of the hardware configuration of an HVAC ECU in the present disclosure; FIG. 3 is a diagram showing an HVAC ECU including a plurality of drive circuits in a circuit example; FIG. 4 is a diagram illustrating the relationship between the on / off state of each drive switch and the direction of current flow in a damper motor in a circuit example; FIG. 5 is a diagram showing the circuit configuration of an HVAC ECU in a first embodiment of the present disclosure; and FIG. 6 is a diagram showing the circuit configuration of an HVAC ECU and a damper motor in a modified example of the first embodiment of the present disclosure.

[0012] An embodiment of a motor drive device, an air conditioner, a motor drive method, and a motor drive program according to the present disclosure will be described below with reference to the drawings. In the following description, when there are multiple similar components and the similar components are to be individually distinguished, one of the letters a to d will be added to the end of the reference numeral, and when the similar components are not to be individually distinguished, the letters a to d will be omitted.

[0013] Fig. 1 is a schematic diagram showing a portion of the configuration of an air conditioner 1 according to the present disclosure. As shown in Fig. 1, the air conditioner 1 includes an HVAC ECU (Heating, Ventilation and Air Conditioning Electric Control Unit) (motor drive device) 20 that controls a damper motor 22 (described later). The air conditioner 1 also includes multiple damper motors 22, a blower motor 31, and various sensors 32.

[0014] The air conditioner 1 includes a refrigerant circuit having a compressor (not shown) that compresses a refrigerant, a condenser (not shown) that condenses the compressed refrigerant, an expansion valve (not shown) that expands the condensed refrigerant, and an evaporator (not shown) that evaporates the expanded refrigerant, as well as multiple damper motors 22 controlled by the HVAC ECU 20. The refrigerant evaporated by the evaporator becomes gaseous and returns to the compressor. The air conditioner 1 adjusts the temperature of the space to be air-conditioned by using the refrigerant circuit through which the refrigerant circulates. Other components of the air conditioner 1 are not described in detail here, as known components may be used.

[0015] The HVAC ECU 20 includes a CPU (controller) 21, a drive circuit 23, and a selector switch 25. The HVAC ECU 20 is connected to a blower motor 31, various sensors 32, a plurality of damper motors 22, and the like via cables. The HVAC ECU 20 receives detected values ​​from the various sensors and controls the operation of various actuators in accordance with the operating conditions of the air conditioner 1. Specifically, the HVAC ECU 20 adjusts heating and cooling in accordance with the room temperature and outside air temperature, and controls the damper motors 22 to maintain appropriate temperature, humidity, or air quality. Details of the control of the damper motors 22 by the HVAC ECU 20 will be described later.

[0016] The damper motor 22 adjusts the air flow inside the air conditioner and supplies air whose temperature has been adjusted by heating or cooling to a specific space or direction. The damper motor 22 may have a function to switch between taking in fresh air from the outside and circulating air within the space to be air-conditioned.

[0017] 2 is a diagram showing an example of a hardware configuration of the HVAC ECU 20 according to the present disclosure. As shown in FIG. 2 , the HVAC ECU 20 is a computer (calculator) and includes, for example, a CPU (Central Processing Unit: processor) 21, a main memory 212, a secondary storage 213, a communication interface 214, and the like. The HVAC ECU 20 may also include an input device 215 that accepts input from a user, a display 216, and the like. The HVAC ECU 20 may also include a drive circuit 23 and a selector switch 25. These components are connected to each other via, for example, a bus 218.

[0018] The main storage device 212 is composed of writable memory such as cache memory, RAM (Random Access Memory), etc., and is used as a work area for reading execution programs of the CPU 21 and writing processing data by the execution programs. The secondary storage device 213 is a non-transitory computer-readable storage medium. Examples of the secondary storage device 213 include magnetic disks such as HDDs (Hard Disk Drives), magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories such as SSDs (Solid State Drives).

[0019] 3 is a diagram showing an HVAC ECU 20' including a plurality of drive circuits 23' in a circuit example. The HVAC ECU 20' includes a CPU 21' and a drive circuit 23'. The drive circuit 23' includes a plurality of drive switches 231a' to 231d'. Similarly, the drive circuit 23'' includes a plurality of drive switches 231a'' to 231d''. The drive switches 231a' to 231d' and 231a'' to 231d'' are, for example, transistors. The CPU 21' outputs a switching control signal (e.g., a PWM signal) to each of the drive switches 231a' to 231d' and 231a'' to 231d'' to selectively drive the damper motors 22a' and 22b'. The on / off states of the drive switches 231a' to 231d' and 231a" to 231d" are switched in response to a control switching signal, and switching the on / off states of the drive switches 231a' to 231d' and 231a" to 231d" switches which of the damper motors 22a' and 22b' is to receive power from the power supply 24'. The CPU 21' controls the damper motor 22' to be driven by switching the on / off states of the drive switches 231a' to 231d' and 231a" to 231d". A known method may be used as appropriate to generate the switching control signal output by the CPU 21', and a detailed description thereof will not be given here.

[0020] FIG. 4 is a diagram illustrating the relationship between the on / off states of the drive switches 231a' to 231d' in the circuit example and the direction of current flow in the damper motor 22a'. For ease of explanation, the drive switches 231a'' to 231d'' and the damper motor 22b' are not shown in FIG. 4, but they are controlled in the same way. For example, when the CPU 21' outputs a switching control signal to turn on the drive switches 231a' and 231c' and turn off the drive switches 231b' and 231d', the current flowing from the power supply 24' flows through the motor coil of the damper motor 22a' to the drive switches 231a' and 231c' that are in the on state (indicated by the black arrows in FIG. 4). Conversely, when the CPU 21' outputs a switching control signal to turn on the drive switches 231b' and 231d' and turn off the drive switches 231a' and 231c', the current flowing from the power supply 24' flows to each of the drive switches 231b' and 231d' that are in the on state via the motor coil of the damper motor 22a' (white arrows in Figure 4).

[0021] The CPU 21' controls the driving of the damper motor 22a' by switching each of the drive switches 231a' to 231d' on / off in accordance with the operation of the air conditioner 1. For example, the CPU 21' may provide a phase difference between the drive switches 231a' to 231d' with respect to the timing at which each drive switch is switched. For example, the pair of two drive switches 231a' and 231c' and the pair of two drive switches 231b' and 231d' may be switched on alternately every half cycle. The timing at which each of the drive switches 231b' to 231d' is turned on may be shifted by a quarter cycle, based on the timing at which the drive switch 231a' is turned on.

[0022] In the examples shown in FIGS. 3 and 4 , as the number of damper motors 22′ increases, the number of drive circuits 23′ increases accordingly, requiring additional circuit area for the drive circuits 23′. As the number of drive circuits 23′ increases, the CPU 21′ requires a CPU port for each drive circuit 23′. In other words, as the number of damper motors 22 to be controlled increases, the number of CPU ports required by the CPU 21′ also increases proportionally. If the number of required ports for the CPU 21′ increases, there is a possibility that there will be a shortage of CPU ports, which may necessitate the replacement of the CPU 21′. Furthermore, the wiring between the various components of the air conditioner 1 may become complicated, potentially making board design difficult. In light of these circumstances, the inventors have studied a configuration for the HVAC ECU 20 that does not require an increase in the number of drive circuits 23, even when controlling multiple damper motors 22.

[0023] [First embodiment] (Configuration of HVAC ECU) Hereinafter, a first embodiment of the present disclosure will be described with reference to Fig. 5. Fig. 5 is a diagram showing a circuit configuration of an HVAC ECU 20 in the first embodiment of the present disclosure. The HVAC ECU 20 in the first embodiment of the present disclosure differs from the HVAC ECU 20' illustrated in Figs. 3 and 4 in that a selector switch 25 is used to switch the connection between a power supply 24 and the damper motors 22 to be controlled, thereby controlling the drive of multiple damper motors 22 using a single drive circuit 23.

[0024] The CPU 21 selects a damper motor 22 to be controlled from among the multiple damper motors 22, outputs a switching control signal to the selector switch 25 to connect the damper motor 22 to be controlled to the power supply 24, and outputs a drive control signal to the drive circuit 23 to drive the damper motor 22 to be controlled.

[0025] The switching control signal output by the CPU 21 is, for example, a voltage signal. The voltage signal is, for example, a binary voltage signal of H / L. The CPU 21 switches the connection state of each switch element 251 by outputting either an H or L voltage signal to each switch element 251 included in the changeover switch 25. Each switch element turns on when an H voltage signal is output, and turns off when an L voltage signal is output. The switching control signal is not limited to a voltage signal, and may be any control signal that can switch the connection state of the switch element 251.

[0026] The drive control signal output by the CPU 21 is, for example, a PWM signal. A PWM signal can be switched on / off at high speed and operates at a high frequency. The CPU 21 controls the power of the damper motor 22, which is the object of control, by changing the duty cycle of each PWM signal output to each drive switch 231. The drive control signal is not limited to a PWM signal and may be any control signal that can switch the connection state of the drive switch 231.

[0027] The drive circuit 23 is provided corresponding to the multiple damper motors 22 (22a, 22b) and selectively drives one of the damper motors 22. The drive circuit 23 includes multiple drive switches 231a-231d and multiple protection elements 26a-26d for ESD protection corresponding to each of the drive switches 231a-231d. The drive switches 231a-231d are, for example, transistors. The drive switches 231a-231d are not limited to transistors and may be any device that functions as a switching element. Details of the protection elements 26 will be described later. Each of the multiple drive switches 231a-231d is connected to a corresponding motor coil on the positive or negative side of each of the A-phase and B-phase of the damper motor 22 to be controlled. The damper motor 22 is controlled by controlling the on / off of each of the drive switches 231a-231d. For example, the drive switch 231a is connected to the positive motor coil of the A phase of the damper motor 22, the drive switch 231b is connected to the negative motor coil of the A phase of the damper motor 22, the drive switch 231c is connected to the positive motor coil of the B phase of the damper motor 22, and the drive switch 231d is connected to the negative motor coil of the B phase of the damper motor 22.

[0028] In this embodiment, the drive switches 231a to 231d included in the drive circuit 23 and the motor coils of the damper motors 22a and 22b are connected externally to the HVAC ECU 20. By connecting the drive circuit 23 and the motor coils of each phase of the damper motor 22 externally to the HVAC ECU 20 in this manner, the number of input lines to the HVAC ECU 20 can be reduced, and the connector of the HVAC ECU 20 can be made smaller.

[0029] The changeover switch 25 is disposed between the power supply 24 and the plurality of damper motors 22, and switches the damper motors 22 connected to the power supply 24. The changeover switch 25 is configured to allow current to flow in both directions. For example, the changeover switch 25 includes a plurality of switch elements 251a and 251b. Either the switch element 251a or 251b is turned on in response to a switch control signal output by the CPU 21. In response to the switch element 251 being turned on, the wiring state is switched so that the damper motor 22 to be controlled and the power supply 24 are electrically connected.

[0030] The switch elements 251a and 251b included in the changeover switch 25 are, for example, semiconductor switches capable of passing current in both directions, and may be solid-state relays. The switch elements 251a and 251b may also be mechanical switches that are electrically connected through physical contact. By using the switch element 251 configured to pass current in both directions, the possibility of the changeover switch 25 being damaged by a reverse current or overvoltage that occurs when the damper motor 22 is driven can be reduced, and the possibility of the HVAC ECU 20 failing can be reduced. The switch elements 251a and 251b are not limited to this example, and may be any switch element 251 configured to pass current in both directions.

[0031] Each of the multiple protection elements 26a to 26d is connected between the damper motor 22 and each of the drive switches 231a to 231d. The protection elements 26 are, for example, Zener diodes. Zener diodes have the property of converting a reverse bias voltage into a stable Zener voltage. The Zener diodes can prevent elements included in the HVAC ECU 20 from being damaged by electrostatic discharge (ESD) or overvoltage generated in the HVAC ECU 20.

[0032] (Operation of the HVAC ECU) The HVAC ECU 20 controls the drive of each damper motor in accordance with the operating conditions of the air conditioner 1. Specifically, the CPU 21 included in the HVAC ECU 20 outputs a drive control signal to the drive circuit 23 and a switching control signal to the selector switch 25. When controlling the drive of only the damper motor 22a among the multiple damper motors 22, the CPU 21 selects the damper motor 22a as the controlled motor and outputs a switching control signal to the selector switch 25 for connecting the controlled damper motor 22a to the power supply 24. The selector switch 25 turns on the switch element 251a and turns off the switch element 251b based on the switching control signal output from the CPU 21. Current supplied from the power supply 24 is supplied to the motor coil of each phase of the damper motor 22a in accordance with the control state of the drive circuit 23.

[0033] The CPU 21 turns on the drive switches 231a and 231c and turns off the drive switches 231b and 231d. In this case, the current flowing through the damper motor 22a flows from the power supply 24 to the motor coil on the A-phase positive side and the motor coil on the B-phase positive side of the damper motor 22a via the switch element 251a. The current flowing through the motor coil on the A-phase positive side of the damper motor 22a passes through the drive switch 231a to ground, and the current flowing through the motor coil on the B-phase positive side of the damper motor 22a passes through the drive switch 231c to ground.

[0034] A protection element 26a, which is a Zener diode, is connected between the motor coil on the A-phase positive side of the damper motor 22a and the drive switch 231a. The protection element 26a reduces the possibility of damage to elements included in the HVAC ECU 20 due to electrostatic discharge (ESD) or overvoltage occurring in the HVAC ECU 20. Similarly, a protection element 26c, which is a Zener diode, is connected between the motor coil on the B-phase positive side of the damper motor 22a and the drive switch 231c.

[0035] After a predetermined time has elapsed, the CPU 21 outputs a drive control signal to the drive circuit 23 to turn on the drive switches 231b and 231d and to turn off the drive switches 231a and 231c. In this case, the current flowing through the damper motor 22a flows from the power supply 24 via the switch element 251a to the A-phase negative side motor coil and the B-phase negative side motor coil of the damper motor 22a. The current flowing through the A-phase negative side motor coil of the damper motor 22a passes through the drive switch 231b to ground, and the current flowing through the B-phase negative side motor coil of the damper motor 22a passes through the drive switch 231d to ground.

[0036] A protection element 26b, which is a Zener diode, is connected between the motor coil on the negative side of the A phase of the damper motor 22a and the drive switch 231b. The protection element 26b reduces the possibility of damage to elements included in the HVAC ECU 20 due to electrostatic discharge (ESD) or overvoltage occurring in the HVAC ECU 20. Similarly, a protection element 26d, which is a Zener diode, is connected between the motor coil on the negative side of the B phase of the damper motor 22a and the drive switch 231d.

[0037] The CPU 21 outputs different drive control signals to the drive circuit 23 at predetermined time intervals, thereby switching the on / off states of the drive switches 231a to 231d and controlling the damper motor 22a to rotate in either a clockwise (CW) or counterclockwise (CCW) direction.

[0038] When switching the controlled object from the damper motor 22a to the damper motor 22b in response to the operating conditions of the air conditioner 1, the CPU 21 outputs a switching control signal to the changeover switch 25 to connect the controlled damper motor 22b to the power supply 24. The changeover switch 25 turns off the switch element 251a and turns on the switch element 251b based on the switching control signal output from the CPU 21. As a result, the current supplied from the power supply 24 is supplied to the motor coil of each phase of the damper motor 22b in response to the control state of the drive circuit 23.

[0039] Even when the damper motor 22b is the control target, the CPU 21 can control the damper motor 22a to rotate in either a clockwise (CW) or counterclockwise (CCW) direction by switching the on / off state of each of the drive switches 231a to 231d at predetermined time intervals, just as when the damper motor 22a is the control target. The CPU 21 may also appropriately switch which of the damper motors 22a and 22b is the control target, depending on the operating conditions of the air conditioner 1.

[0040] In the example of this embodiment, there are two damper motors 22a, 22b and two switch elements 251a, 251b, but this is not limiting, and the number of damper motors 22 and switch elements 251 may be four. Any number of damper motors 22 and switch elements 251 may be used, and even in this case, the multiple damper motors 22 are driven by a common drive circuit 23.

[0041] In this way, regardless of whether the damper motor 22a or 22b is to be controlled, the damper motor 22 can be controlled using the same drive circuit 23. This eliminates the need to provide additional drive circuits 23 in response to an increase in the number of damper motors 22, simplifying the configuration and wiring of the HVAC ECU 20. For example, when adding one motor to the HVAC ECU 20 of the present disclosure, control becomes possible by simply adding one switch element 251 of the selector switch 25 and one CPU port of the CPU 21.

[0042] The switch elements 251a and 251b of the changeover switch 25 are, for example, semiconductor switches that allow current to flow in both directions, and may be, for example, solid-state relays. The switch elements 251a and 251b may also be mechanical switches that are electrically connected by physical contact. This reduces the possibility of damage to the changeover switch 25 due to reverse current or overvoltage that occurs when the damper motor 22 is driven, and reduces the possibility of failure of the HVAC ECU 20.

[0043] ESD protection elements 26a to 26d are connected between the motor coils corresponding to each phase of the damper motors 22a and 22b and the drive switches 231a to 231d. This prevents static electricity from damaging the elements included in the HVAC ECU 20. Because a single drive circuit 23 can control the drive of multiple motors, the number of protection elements 26 does not increase in response to an increase in the number of drive circuits 23. This prevents increases in the cost and board area of ​​the HVAC ECU 20. Even if the number of damper motors 22 increases, the number of wiring lines can be prevented from increasing. This improves the resistance to noise generated during operation of the HVAC ECU 20.

[0044] From the viewpoint of thermal design, the drive circuits 23 correspond to heat sources. Therefore, by suppressing an increase in the number of drive circuits 23, which are heat sources, the thermal design can be simplified.

[0045] Each of the drive switches 231a to 231d included in the drive circuit 23 and each of the motor coils of the damper motors 22a and 22b are connected externally to the HVAC ECU 20. By connecting the drive circuit 23 and the motor coils of each phase of the damper motor 22 externally to the HVAC ECU 20 in this manner, the number of input lines to the HVAC ECU 20 can be reduced, and the connector of the HVAC ECU 20 can be made smaller.

[0046] [Modification of First Embodiment] A modification of the first embodiment of the present disclosure will be described below with reference to Fig. 6. Fig. 6 is a diagram showing the circuit configuration of the HVAC ECU 20 and the damper motor 22 in a modification of the first embodiment of the present disclosure. This modification differs from the first embodiment in that the drive switches 231a to 231d provided in the drive circuit 23 and the motor coils of the damper motors 22a and 22b are connected inside the HVAC ECU 20. Other configurations and operations of the HVAC ECU 20 are similar to those of the first embodiment, and therefore will not be described again.

[0047] In this modification, the drive switches 231a to 231d of the drive circuit 23 and the motor coils of the damper motors 22a and 22b are connected inside the HVAC ECU 20. By connecting the drive circuit 23 and the motor coils of each phase of the damper motor 22 inside the HVAC ECU 20 in this way, the number of external wirings of the HVAC ECU 20 can be reduced, and noise resistance can be improved. This makes it possible to prevent a decrease in electro-magnetic compatibility (EMC) and malfunction of the entire system.

[0048] <Additional Notes> While the present disclosure has been described above using embodiments, the technical scope of the present disclosure is not limited to the scope of the above embodiments. Various modifications or improvements can be made to the above embodiments without departing from the gist of the present disclosure, and such modifications or improvements are also included in the technical scope of the present disclosure. The above embodiments may be combined as appropriate. For example, in the above embodiments, the HVAC ECU 20 is described as an example of the motor drive device 20, but this example is not limiting. Instead of the HVAC ECU 20, a motor driver appropriate for the type of multiple motors to be driven and the usage environment may be used as appropriate. In the above embodiments, the CPU 21 is described as an example of a controller, but this example is not limiting. An FPGA or an ASIC may also be used.

[0049] The motor drive device, air conditioner, motor drive method, and motor drive program described in the above-described embodiments can be understood, for example, as follows: A motor drive device (20) according to a first aspect of the present disclosure includes: drive circuits (23) provided corresponding to a plurality of motors (22) and selectively driving the motors; a changeover switch (25) disposed between a power source (24) and the plurality of motors and switching the motor connected to the power source; and a controller (21) that selects a motor to be controlled from the plurality of motors, outputs a changeover control signal to the changeover switch for connecting the motor to be controlled to the power source, and outputs a drive control signal to the drive circuit for driving the motor to be controlled, the changeover switch being configured to allow current to flow in both directions.

[0050] According to the motor drive device of the present disclosure, a controller outputs control signals to the drive circuit and the selector switch, respectively, thereby switching which of multiple motors receives power. This eliminates the need to provide a drive circuit for each motor, simplifying the configuration and wiring of the motor drive device. The selector switch is, unlike a switching element such as a transistor, a mechanical switch or solid-state relay, for example, that allows current to flow in both directions. This reduces the possibility of damage to the selector switch due to reverse current generated when driving the motor, thereby reducing the possibility of failure of the motor drive device. Adding another motor to the motor drive device of the present disclosure requires only adding one switch element to the selector switch and one CPU port to the driver to enable control.

[0051] A motor drive device according to a second aspect of the present disclosure is the first aspect, wherein the drive circuit includes a plurality of drive switches (231a to 231d) and a plurality of protection elements (26a to 26d) for ESD protection corresponding to each of the drive switches, and each of the protection elements is wired between the motor and each of the drive switches.

[0052] According to the motor drive device of the present disclosure, by connecting protective elements (e.g., Zener diodes) for ESD (Electrostatic Discharge) protection between the motor and each drive switch, damage to elements included in the motor drive device due to static electricity can be prevented. Because the configuration uses drive circuits corresponding to multiple motors, the number of protective elements does not increase in response to an increase in the number of drive circuits. This prevents increases in the cost and size of the motor drive device. Because the number of wirings provided in the motor drive device can be reduced, resistance to noise generated during operation of the motor drive device can be improved.

[0053] The motor drive device of a third aspect of the present disclosure is the motor drive device of the first or second aspect, wherein the drive circuit and wiring for each phase of the motor are connected outside the motor drive device.

[0054] According to the motor drive device of the present disclosure, the number of internal wirings of the motor drive device can be reduced, the number of input lines to the motor drive device can be reduced, and the connector of the motor drive device can be made smaller.

[0055] The motor drive device of a fourth aspect of the present disclosure is the motor drive device of the first or second aspect, wherein the drive circuit and wiring for each phase of the motor are connected inside the motor drive device.

[0056] The motor drive device of the present disclosure can reduce the number of external wirings of the motor drive device and improve noise resistance, thereby preventing a deterioration in electro-magnetic compatibility (EMC) performance and causing malfunctions in the entire system.

[0057] An air conditioner (1) of a fifth aspect of the present disclosure includes a compressor, a condenser, an evaporator, and a motor controlled by the motor drive device of any one of the first to fourth aspects.

[0058] A motor driving method according to a sixth aspect of the present disclosure includes the steps of: selectively driving a plurality of motors using drive circuits (23) provided corresponding to the motors; switching the motor connected to the power source using a changeover switch (25) arranged between a power source and the plurality of motors and configured to allow current to flow in both directions; selecting a motor to be controlled from the plurality of motors, outputting a changeover control signal to the changeover switch for connecting the motor to be controlled to the power source, and outputting a drive control signal to the drive circuit for driving the motor to be controlled.

[0059] The motor drive program of the seventh aspect of the present disclosure causes a computer to execute the following processes: a process of selectively driving a plurality of motors using drive circuits (23) provided corresponding to the plurality of motors; a process of switching the motor connected to the power source using a changeover switch (25) arranged between a power source and the plurality of motors and configured to allow current to flow in both directions; and a process of selecting a motor to be controlled from the plurality of motors, outputting a changeover control signal to the changeover switch for connecting the motor to be controlled to the power source, and outputting a drive control signal to the drive circuit for driving the motor to be controlled.

[0060] 1 Air conditioner 20, 20' HVAC ECU (motor drive device) 21, 21' CPU 22, 22a, 22b, 22a', 22b' Damper motor (motor) 23, 23', 23'' Drive circuit 231, 231a to 231d, 231a' to 231d', 231a'' to 231d'' Drive switch 24, 24' Power supply 25 Changeover switch 251, 251a, 251b Switch element 26, 26a to 26d Protection element 31 Blower motor 32 Sensor 212 Main memory device 213 Secondary memory device 214 Communication I / F 215 Input device 216 Display 218 Bus

Claims

1. A motor driving device comprising: a drive circuit provided corresponding to a plurality of motors and configured to selectively drive the motors; a changeover switch disposed between a power source and the plurality of motors and configured to switch the motors connected to the power source, the changeover switch being capable of passing current in both directions; and a controller configured to select a motor to be controlled from among the plurality of motors, output a changeover control signal for connecting the selected motor to be controlled to the power source to the changeover switch, and output a drive control signal for driving the selected motor to be controlled to the drive circuit.

2. The motor driving device according to claim 1, wherein the drive circuit includes a plurality of drive switches and a plurality of protection elements for ESD countermeasures corresponding to the respective drive switches, and each of the plurality of protection elements is connected between the motor and the respective drive switch.

3. The motor driving device according to claim 1, wherein the wiring of each phase of the drive circuit and the motor is connected outside the motor driving device.

4. The motor driving device according to claim 1, wherein the wiring of each phase of the drive circuit and the motor is connected inside the motor driving device.

5. An air conditioner comprising: a refrigerant circuit having a compressor configured to compress a refrigerant, a condenser configured to condense the compressed refrigerant, an expansion valve configured to expand the condensed refrigerant, and an evaporator configured to evaporate the expanded refrigerant; and a plurality of motors controlled by the motor driving device according to claim 1.

6. A motor driving method comprising: a step of selectively driving the motors using a drive circuit provided corresponding to the plurality of motors; a step of switching the motors connected to the power source using a changeover switch disposed between the power source and the plurality of motors and configured to pass current in both directions; and a step of selecting a motor to be controlled from among the plurality of motors, outputting a changeover control signal for connecting the selected motor to be controlled to the power source to the changeover switch, and outputting a drive control signal for driving the selected motor to be controlled to the drive circuit.

7. A motor drive program for causing a computer to execute: a process of selectively driving the motor using a drive circuit provided corresponding to a plurality of motors; a process of switching the motor connected to the power supply using a changeover switch arranged between the power supply and the plurality of motors and configured to be able to conduct current in both directions; and a process of selecting a motor to be a control target among the plurality of motors, outputting a changeover control signal for connecting the control target motor and the power supply to the changeover switch, and outputting a drive control signal for driving the control target motor to the drive circuit.

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