JP2017050948A - Motor drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive device capable of resolving an overvoltage state, and preventing damages of an element in a circuit caused by heat.SOLUTION: In a case where a voltage detected by an overvoltage determination unit 90 is equal to or more than a threshold voltage, an FET driver 70 makes an inverter 40 generate a forced operation voltage for forcibly rotating a motor 52 and apply it to the motor 52. In addition, in a case where an overheat state determination unit 86 determines that a substrate is in an overheat state at the forced operation, the FET driver 70 controls the inverter circuit 40 to interrupt the application of the forced operation voltage until the overheat state determination unit 86 determines that the overheat state is resolved.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a motor drive device.

  A blower motor (hereinafter abbreviated as “motor”) used to blow air from a vehicle air conditioner and a power source for a circuit for controlling the motor are in-vehicle batteries. The battery is also connected to devices such as an engine ignition system and an alternator. ing. Due to the influence of these devices connected to the battery, a surge in which the voltage of the power supplied to the motor and the circuit that controls the motor fluctuates, and the circuit may be adversely affected by the surge.

  Among surges, the load dump surge generated when the electrical connection between the alternator and the battery during power generation is cut off is particularly high in voltage, which may have a fatal effect on a circuit composed of semiconductors. Patent Document 1 discloses an invention of a drive device that, when a momentary abnormal increase in power supply voltage due to a load dump is detected, energizes a motor and an electromagnetic coil to suppress the abnormal increase in power supply voltage.

  Patent Document 2 discloses an invention of a drive device for a secondary air introduction system that, when a momentary abnormal increase in power supply voltage due to a load dump is detected, energizes a motor and an electromagnetic coil to suppress the abnormal increase in power supply voltage. ing.

JP 2007-274828 A JP 2005-307957 A

  However, the inventions described in Patent Document 1 and Patent Document 2 are mainly intended to eliminate overvoltage generated in a short time of several tens to several hundreds of milliseconds due to a load dump surge or the like. Therefore, if energization of the motor is continued when an overvoltage state such as a battery quick charger is connected for a long time, the switching element of the drive circuit that generates the voltage for driving the motor may be damaged by heat. was there.

  The present invention has been made in view of the above, and an object of the present invention is to provide a motor drive device that can eliminate an overvoltage state and prevent damage to circuit elements due to heat.

  In order to solve the above-mentioned problem, the motor driving device according to claim 1, wherein the motor driving device generates a voltage to be applied to the motor, and an overheated state for determining whether the substrate is overheated based on the temperature of the substrate. A determination unit, a voltage detection unit for detecting a voltage of a power source, and a forced rotation of the motor when the detection voltage detected by the voltage detection unit exceeds a threshold value while the motor is stopped When the driving circuit is controlled so that the forcible operation voltage is applied to the motor, and the overheating state of the substrate is determined by the overheating state determination unit in a state where the motor is forcibly rotated, And a control unit that controls the drive circuit so that the application of the forced operation voltage to the motor is interrupted until the overheat state determination unit determines that the heating state of the substrate is eliminated.

  In this motor drive device, when the detection voltage detected by the voltage detection unit is equal to or greater than the threshold, the power supply voltage is overvoltaged by causing the drive circuit to generate a forced operation voltage for forcibly rotating the motor and rotating the motor. The state of is canceled.

  In addition, when it is determined that the substrate is in an overheated state in the forced rotation state, the motor driving device is configured to interrupt the application of the forcible operation voltage until it is determined that the overheated state has been eliminated. Damage to the device can be prevented.

  The motor drive device according to claim 2 is the motor drive device according to claim 1, wherein when the command signal is input when the detection voltage is less than the threshold value, the control unit receives the command signal input. Is applied to the motor, the drive circuit is controlled so that the motor rotates at a command rotational speed according to the command signal, and the motor is rotating at the command rotational speed. When the detected voltage is equal to or higher than the threshold, the drive circuit is controlled so that a voltage for rotating the motor at a speed higher than the command rotational speed is applied to the motor, and the motor rotates at a high speed. In a state where the overheat state of the substrate is determined by the overheat state determination unit, the high temperature rotation is performed until it is determined that the overheat state of the substrate is resolved by the overheat state determination unit. Applied to the pressure the motor is interrupted, the command voltage for controlling the drive circuit so as to apply to the motor.

  According to this motor drive device, when the motor is rotating based on the command signal, when the power supply voltage becomes equal to or higher than the threshold voltage, the motor voltage is rotated by rotating the motor at a higher speed than the rotation by the command signal. Eliminates the overvoltage condition.

  In addition, when it is determined that the substrate is in an overheated state while the motor is rotating at a high speed, the motor driving device applies a voltage for high speed rotation until it is determined that the overheated state is resolved. By interrupting and rotating the motor based on the command signal, damage to the elements of the circuit can be prevented.

  According to a third aspect of the present invention, in the motor drive device according to the first or second aspect, the overheat state determination unit sets the temperature of the substrate to a second threshold temperature higher than the first threshold temperature exceeding the first threshold temperature. When the temperature reaches the substrate, it is determined that the substrate is in a heated state, and when the temperature of the substrate is equal to or lower than the first threshold temperature, it is determined that the heated state is eliminated.

  According to this motor drive device, when the temperature of the substrate becomes equal to or lower than the first threshold temperature less than the second threshold, it is determined that the heating state has been eliminated. Forced operation to cancel can be resumed.

It is the schematic which shows the structure of the motor unit using the motor drive device which concerns on embodiment of this invention. It is a figure which shows the outline of the motor drive device which concerns on embodiment of this invention. It is the schematic which showed the mode of operation | movement of the logic circuit of the motor drive device which concerns on embodiment of this invention, (A) is when a power supply voltage is less than a threshold voltage and a board | substrate is not an overheating state, (B) is When the power supply voltage is equal to or higher than the threshold voltage and the substrate is not overheated, (C) shows the case where the power supply voltage is equal to or higher than the threshold voltage and the substrate is overheated. It is the time chart which showed an example of the change of the power supply voltage, a drive signal, and board | substrate temperature by the process of the overvoltage elimination in the motor drive device which concerns on embodiment of this invention. It is the time chart which showed an example of the change of a power supply voltage, a drive signal, and a substrate temperature at the time of continuing the process of overvoltage cancellation without interrupting. It is the flowchart which showed an example of the overvoltage elimination process in the motor drive device which concerns on embodiment of this invention.

  FIG. 1 is a schematic diagram showing a configuration of a motor unit 10 using a motor drive device 20 according to the present embodiment. The motor unit 10 according to the present embodiment in FIG. 1 is a so-called blower motor unit used for blowing air from a vehicle air conditioner as an example.

  The motor unit 10 according to the present embodiment relates to a three-phase motor having an outer rotor structure in which a rotor 12 is provided outside a stator 14. The stator 14 is an electromagnet in which a lead wire is wound around a core member, and constitutes three phases of a U phase, a V phase, and a W phase.

  Each of the U-phase, V-phase, and W-phase of the stator 14 generates a so-called rotating magnetic field by switching the polarity of the magnetic field generated by the electromagnet under the control of the motor drive device 20 described later.

  A rotor magnet is provided inside the rotor 12 (not shown), and the rotor magnet rotates the rotor 12 by responding to the rotating magnetic field generated by the stator 14.

  The rotor 12 is provided with a shaft 16 and rotates integrally with the rotor 12. Although not shown in FIG. 1, in the present embodiment, the shaft 16 is provided with a multi-blade fan such as a so-called sirocco fan, and the multi-blade fan rotates together with the shaft 16, thereby blowing air in the vehicle air conditioner. It becomes possible.

  The stator 14 is attached to the motor drive device 20 via the upper case 18. The motor drive device 20 includes a substrate 22 of the motor drive device 20 and a heat sink 24 that dissipates heat generated from elements on the substrate 22.

  A lower case 28 is attached to the motor unit 10 including the rotor 12, the stator 14, and the motor drive device 20.

  FIG. 2 is a diagram schematically showing the motor drive device 20 according to the present embodiment. The inverter circuit 40 shown in FIG. 2 switches the electric power supplied to the coil of the stator 14 of the motor 52 by FET (Field Effect Transistor). For example, the inverter FETs 44A and 44D switch the power supplied to the U-phase coil 14U, the inverter FETs 44B and 44E switch to the V-phase coil 14V, and the inverter FETs 44C and 44F switch the power supplied to the W-phase coil 14W.

  The drains of the inverters FETs 44A, 44B, and 44C are connected to the positive electrode of the on-vehicle battery 80 via the choke coil 82. The sources of the inverters FET 44D, 44E, and 44F are connected to the negative electrode of the battery 80.

  Further, on the substrate of the motor drive device 20 of the present embodiment, in addition to the inverter circuit 40 described above, a comparator 54, an actual rotation speed calculation unit 56, a command rotation speed calculation unit 58, a standby circuit 60, a main power supply energization unit 62, an energization control drive waveform determination unit 64, a PI control unit 66, a voltage correction unit 68, an FET driver 70, and the like are mounted.

  Further, a choke coil 82 and smoothing capacitors 84A and 84B are mounted on the substrate of the motor drive device 20 of the present embodiment, and an air conditioner ECU (Electronic Control Unit) 78 and a battery 80 are connected. The choke coil 82 and the smoothing capacitors 84A and 84B together with the battery 80 constitute a substantially DC power source. The air conditioner ECU 78 is an electronic control unit for the vehicle air conditioner. When the user turns on the air conditioner by the air conditioner ECU 78, the motor 52 is operated by the control of the motor driving device 20. When the user adjusts the air volume of the vehicle air conditioner, a signal for instructing the rotational speed of the motor 52 (rotor 12) is input via the air conditioner ECU 78.

  In the present embodiment, the Hall element 12B detects the magnetic field of the sensor magnet 12A provided coaxially with the shaft 16. The comparator 54 is a device that converts the analog output of the Hall element 12 </ b> B into a digital signal, and the actual rotational speed calculation unit calculates the actual rotational speed of the rotor 12 based on the digital signal output from the comparator 54. The command rotation number calculation unit calculates a target rotation speed based on an instruction from the air conditioner ECU 78 or the like.

  The PI controller 66 changes the coil of the stator 14 when changing the actual rotational speed to the target rotational speed from the target rotational speed calculated by the command rotational speed calculator 58 and the actual rotational speed calculated by the actual rotational speed calculator 56. The voltage applied to is calculated by so-called PI control. The PI control unit 66 includes a deviation proportional unit 66P that calculates a voltage at the target rotational speed based on a proportional relationship between a deviation between the target rotational speed and the actual rotational speed and a deviation between the voltage at the target rotational speed and the voltage at the actual rotational speed. Including. Further, the PI control unit 66 includes a deviation integration unit 66I that eliminates the residual deviation by deviation integration when the residual deviation is generated only by the proportional relationship. The voltage correction unit 68 corrects the voltage applied to the coil of the stator 14 based on the calculation result by the PI control unit 66.

  The standby circuit 60 is a circuit that controls power supply from the battery 80 to each unit. Further, the main power supply energization unit 62 turns on the power supply to the motor drive device according to the control of the standby circuit 60 and causes the energization control drive waveform determination unit 64 to determine the waveform of the voltage applied to the coil of the motor 52. Further, the main power supply energization unit 62 applies the power supply voltage to the overvoltage determination unit 90. The overvoltage determination unit 90 is a circuit such as a comparator, and determines whether the applied power supply voltage is equal to or higher than a threshold voltage. The overvoltage determination unit 90 outputs a high level (H level) signal when the power supply voltage is equal to or higher than the threshold voltage, and outputs a low level (L level) signal when the power supply voltage is lower than the threshold voltage. To each output.

  A chip thermistor RT that detects the temperature of the substrate as a resistance value is mounted on the substrate of the motor drive device 20 according to the present embodiment. The chip thermistor RT used in this embodiment is an NTC (Negative Temperature Coefficient) thermistor whose resistance decreases with increasing temperature, and the resistance value of the chip thermistor RT decreases with increasing temperature. Note that a PTC (Positive Temperature Coefficient) thermistor whose resistance value increases as the temperature rises by using an inverting circuit together may be used.

  The chip thermistor RT constitutes a kind of voltage dividing circuit, and a voltage that changes based on the resistance value of the chip thermistor RT is output from one end of the chip thermistor RT. If the chip thermistor RT is an NTC thermistor, the resistance decreases as the temperature increases, and the voltage divided and output from one end also decreases as the temperature increases.

  The voltage output from one end of the chip thermistor RT is compared with the overheat determination value output from the overheat determination value output unit 88 in the overheat state determination unit 86. When the voltage output from one end of the chip thermistor RT is equal to or lower than the overheat determination value, the overheat state determination unit 86 generates an H level signal indicating that the substrate is in a heated state, and the voltage output from one end of the chip thermistor RT. When the value exceeds the overheat determination value, an L level signal is output to each logic circuit 108 described later.

  The forcible output unit 92 is a circuit that outputs an H level signal for forcible operation for forcibly driving the motor 52 to the logic circuit 108 when the power supply voltage is equal to or higher than the threshold voltage.

  The logic circuit 108 includes a first NOT gate 96 whose input terminal is connected to the output terminal of the overvoltage determination unit 90, and a first OR gate whose input terminal is connected to the output terminals of the overheat state determination unit 86 and the first NOT gate 96. 98.

  The logic circuit 108 includes a second NOT gate 100 whose input terminal is connected to the output terminal of the overheat state determination unit 86, and an input terminal whose output terminals are the forced output unit 92, the overvoltage determination unit 90, and the second NOT gate 100. And a first AND gate 102 connected to.

  Further, the logic circuit 108 has an input terminal connected to the output terminal of each of the first OR gate 98 and the voltage correction unit 68, and an input terminal connected to the output of each of the first AND gate 102 and the second AND gate 104. And a second OR gate 106 having an output terminal connected to the FET driver 70.

  The logic circuit 108 determines which of the H level signal output from the forced output unit 92 and the signal (L level) output from the voltage correction unit 68 according to the signals output from the overvoltage determination unit 90 and the overheat state determination unit 86. These signals are output to the FET driver 70. When an H level signal is input from the logic circuit 108, the FET driver 70 generates a voltage for forced operation (forced operation voltage) for forcibly driving the motor 52 at a higher speed than during normal operation. 40. In addition, when the L level signal is input from the logic circuit 108, the FET driver 70 generates an voltage having a voltage value corresponding to the signal output from the voltage correction unit 68 based on the command signal. A normal operation for controlling 40 is performed. In the present embodiment, when a voltage (command voltage) having a voltage value corresponding to the signal output from the voltage correction unit 68 is applied to the motor 52, the motor 52 is controlled by the command rotation speed described in the claims. Rotate with.

  Further, a shunt resistor 94 for detecting a current is provided between each source of the inverters FETs 44D, 44E, and 44F and the battery 80. In the present embodiment, the current flowing through the motor 52 is detected from the potential difference between both ends of the shunt resistor 94, and the inverter circuit 40 can be controlled in consideration of the change in the current.

  FIG. 3 is a schematic diagram illustrating an operation mode of the logic circuit 108 of the motor driving device 20 according to the present embodiment. FIG. 3A illustrates a case where the power supply voltage is less than the threshold voltage and the substrate is not overheated. (B) shows the case where the power supply voltage is higher than the threshold voltage and the substrate is not overheated, and (C) shows the case where the power supply voltage is higher than the threshold voltage and the substrate is overheated.

  In FIG. 3A, since the power supply voltage is less than the threshold voltage, the overvoltage determination unit 90 outputs an L level signal. Further, since the substrate is not in a heated state, the overheat state determination unit 86 outputs an L level signal.

  The L level signal output from the overvoltage determination unit 90 is inverted to an H level signal by the first NOT gate 96 and input to the first OR gate 98. As a result, since the L level signal from the overheat state determination unit 86 and the H level signal from the first NOT gate 96 are input to the input terminal of the first OR gate 98, the first OR gate outputs the H level signal to the second AND. Output to the gate 104.

  Since the H level signal from the first OR gate 98 and the L level signal from the voltage correction unit 68 are input to the input terminal of the second AND gate 104, the second AND gate 104 outputs an L level signal.

  The L level signal output from the overheat state determination unit 86 is inverted to an H level signal by the second NOT gate 100 and input to the first AND gate 102. Since the L voltage signal from the overvoltage determination unit 90, the H level signal from the forced output unit 92, and the H level signal from the second NOT gate 100 are input to the input terminal of the first AND gate 102, the first AND gate 102 is at the L level. Output a signal.

  Since the L level signal is input from the first AND gate 102 and the L level signal is input from the second AND gate 104 to the input terminal of the second OR gate 106, the second OR gate 06 outputs the L level signal to the FET driver 70. To do. The FET driver 70 to which the L level signal is input performs a normal operation of controlling the inverter circuit 40 so as to generate a voltage having a voltage value corrected based on the signal output from the voltage correction unit 68.

  In FIG. 3B, since the power supply voltage is equal to or higher than the threshold voltage, the overvoltage determination unit 90 outputs an H level signal. Further, since the substrate is not in a heated state, the overheat state determination unit 86 outputs an L level signal.

  The H level signal output from the overvoltage determination unit 90 is inverted to an L level signal by the first NOT gate 96 and input to the first OR gate 98. As a result, since the L level signal from the overheat state determination unit 86 and the L level signal from the first NOT gate 96 are input to the input terminal of the first OR gate 98, the first OR gate outputs the L level signal to the second AND. Output to the gate 104.

  Since the L level signal from the first OR gate 98 and the L level signal from the voltage correction unit 68 are input to the input terminal of the second AND gate 104, the second AND gate 104 outputs the L level signal.

  The L level signal output from the overheat state determination unit 86 is inverted to an H level signal by the second NOT gate 100 and input to the first AND gate 102. Since the H level signal from the overvoltage determination unit 90, the H level signal from the forcing output unit 92, and the H level signal from the second NOT gate 100 are input to the input terminal of the first AND gate 102, the first AND gate 102 is at the H level. Output a signal.

  Since the H level signal from the first AND gate 102 and the L level signal from the second AND gate 104 are input to the input terminal of the second OR gate 106, the second OR gate 06 outputs the H level signal to the FET driver 70. To do. The FET driver 70 to which the H level signal is input causes the inverter circuit 40 to generate a forcible operation voltage that drives the motor 52 at a higher speed than during normal operation.

  In FIG. 3C, since the power supply voltage is equal to or higher than the threshold voltage, the overvoltage determination unit 90 outputs an H level signal. Further, since the substrate is in a heated state, the overheat state determination unit 86 outputs an H level signal.

  The H level signal output from the overvoltage determination unit 90 is inverted to an L level signal by the first NOT gate 96 and input to the first OR gate 98. As a result, since the H level signal from the overheat state determination unit 86 and the L level signal from the first NOT gate 96 are input to the input terminal of the first OR gate 98, the first OR gate outputs the H level signal to the second AND. Output to the gate 104.

  Since the H level signal from the first OR gate 98 and the L level signal from the voltage correction unit 68 are input to the input terminal of the second AND gate 104, the second AND gate 104 outputs an L level signal.

  The H level signal output from the overheat state determination unit 86 is inverted to the L level signal by the second NOT gate 100 and input to the first AND gate 102. Since an H level signal from the overvoltage determination unit 90, an H level signal from the forced output unit 92, and an L level signal from the second NOT gate 100 are input to the input terminal of the first AND gate 102, the first AND gate 102 is at the L level. Output a signal.

  Since the L level signal is input from the first AND gate 102 and the L level signal is input from the second AND gate 104 to the input terminal of the second OR gate 106, the second OR gate 06 outputs the L level signal to the FET driver 70. To do. The FET driver 70 to which the L level signal is input performs a normal operation of controlling the inverter circuit 40 so as to generate a voltage having a voltage value corrected based on the signal output from the voltage correction unit 68.

  FIG. 4 is a time chart showing an example of overvoltage elimination processing in the motor drive device 20 according to the present embodiment. When the power supply voltage + B voltage 110 becomes equal to or higher than the threshold voltage 112, the FET driver 70 outputs a drive signal 114 to cause the inverter circuit 40 to generate a forced operation voltage, and the generated forced operation voltage is supplied to the motor 52. This is applied to drive the motor 52 to eliminate the overvoltage.

When the substrate temperature 116 exceeds the first threshold temperature and reaches the second threshold temperature 120 (time t ₁ ), the application of the forcible operation voltage is interrupted and the forcible driving of the motor 52 is stopped. If the time when at t ₁ does not stop the forced driving of the motor 52, the continued substrate temperature 116 rises as shown FIG. 5, eventually damaging the elements constituting the motor driving device 20. In the present embodiment, after the substrate temperature 116 reaches the second threshold temperature 120, the overheat state determination unit 86 outputs an H level signal, and the substrate temperature 116 outputs the H level signal as the second threshold temperature 120. It continues until it becomes below the 1st threshold temperature 118 lower than.

  When the substrate temperature 116 is the first threshold temperature 118, the overheat state determination unit 86 outputs an H level signal until the substrate temperature 116 reaches the second threshold temperature 120 until the substrate temperature 116 becomes equal to or lower than the first threshold temperature 118. The first overheat determination value corresponding to the voltage output from the chip thermistor RT and the second overheat determination value corresponding to the voltage output from the chip thermistor RT when the substrate temperature 116 is the second threshold temperature 120 are used as the overheat determination value. The output unit 88 outputs the data. If the chip thermistor RT is an NTC thermistor, the resistance decreases as the temperature increases, and the voltage divided and output from one end also decreases as the temperature increases. Therefore, the second overheat determination value is higher than the first overheat determination value. Also lower.

  The overheat state determination unit 86 outputs an H level signal when the voltage output from one end of the chip thermistor RT falls below the first overheat determination value and falls to the second overheat determination value, and then the chip thermistor RT When the voltage output from one end rises to the first overheat determination value, an L level signal is output.

In Figure 4, the substrate temperature 116 at time t ₂ since becomes less than the first threshold temperature, the driving of the motor 52 for the overvoltage solve is resumed. As described above, when the substrate temperature 116 becomes equal to or higher than the second threshold temperature 120, it is possible to prevent the circuit elements of the motor driving device 20 from being damaged by interrupting the forced driving of the motor.

  FIG. 6 is a flowchart showing an example of overvoltage elimination processing in the motor drive device 20 according to the present embodiment. In step 500, it is determined whether or not the + B voltage 110, which is the power supply voltage, has reached the threshold voltage 112 or more and has entered an overvoltage state. If the determination in step 500 is affirmative, the procedure proceeds to step 502. If the determination in step 500 is negative, normal operation is performed in step 504 and the process returns. In the normal operation in step 504, if the vehicle air conditioner is in an off state, the motor 52 stops rotating without forcibly driving the motor 52 for overvoltage elimination, and the vehicle air conditioner is in an on state. If there is, the motor 52 is rotated by causing the inverter circuit 40 to generate a voltage having a voltage value corrected based on the signal output from the voltage correction unit 68 without forcibly driving the motor 52 for overvoltage elimination. .

  In step 502, it is determined whether or not the substrate is in an overheated state. If the determination is affirmative, the procedure is shifted to the normal operation in step 504 to prevent the element from being damaged by heat and the process is returned. If the determination in step 502 is negative, the motor 52 is forcibly operated in step 506 to eliminate the overvoltage, and the process returns.

  As described above, in this embodiment, when the overvoltage determination unit 90 detects a voltage equal to or higher than the threshold voltage, the inverter circuit 40 generates the forcible operation voltage that rotates the motor 52 and rotates the motor 52. As a result, the power supply voltage is eliminated from the overvoltage state.

  Further, in this embodiment, when it is determined that the substrate is in an overheated state during the forced operation, the forced operation is interrupted until it is determined that the overheated state is resolved, thereby damaging the circuit elements. Can be prevented. Therefore, even when an overvoltage state such as the connection of a battery quick charger is continued for a long time, the overvoltage state can be eliminated and damage to circuit elements due to heat can be prevented.

DESCRIPTION OF SYMBOLS 10 ... Motor unit, 12 ... Rotor, 12A ... Sensor magnet, 12B ... Hall element, 14 ... Stator, 14U, 14V, 14W ... Coil, 16 ... Shaft, 18 ... Upper case, 20 ... Motor drive device, 22 ... Substrate, 24 ... Heat sink, 28 ... Lower case, 40 ... Inverter circuit, 44A, 44B, 44C, 44D, 44E, 44F ... Inverter FET, 52 ... Motor, 54 ... Comparator, 56 ... Actual rotational speed calculation unit, 58 ... Command rotational speed Calculation unit, 60 ... standby circuit, 62 ... main power supply energization unit, 64 ... energization control drive waveform determination unit, 66 ... PI control unit, 66I ... deviation integration unit, 66P ... deviation proportional unit, 68 ... voltage correction unit, 70 ... FET driver, 78 ... air conditioner ECU, 80 ... battery, 82 ... choke coil, 84A, 84B ... smoothing capacitor, 6 ... Overheat state determination unit, 88 ... Overheat determination value output unit, 90 ... Overvoltage determination unit, 92 ... Forced output unit, 94 ... Shunt resistance, 96 ... First NOT gate, 98 ... First OR gate, 100 ... Second NOT gate, DESCRIPTION OF SYMBOLS 102 ... 1st AND gate, 104 ... 2nd AND gate, 106 ... 2nd OR gate, 118 ... Logic circuit, 110 ... + B voltage, 112 ... Threshold voltage, 114 ... Drive signal, 116 ... Substrate temperature, 118 ... 1st threshold temperature, 120 ... second threshold temperature, RT ... chip thermistor

Claims (3)

A drive circuit for generating a voltage to be applied to the motor;
An overheating state determination unit for determining whether the substrate is in an overheated state based on the temperature of the substrate;
A voltage detector for detecting the voltage of the power supply;
When the detection voltage detected by the voltage detection unit is equal to or greater than a threshold value while the motor is stopped, the forcible operation voltage for forcibly rotating the motor is applied to the motor. In the state where the drive circuit is controlled and the motor is forcibly rotated, if the overheat state determination unit determines the overheat state of the substrate, the overheat state determination unit determines that the heating state of the substrate is eliminated. Until the application of the forcible operation voltage to the motor is interrupted,
A motor driving device.   When a command signal is input in a state where the detected voltage is less than the threshold, the control unit applies a command voltage corresponding to the input command signal to the motor, and performs command rotation according to the command signal. The drive circuit is controlled so that the motor rotates at a speed, and when the detected voltage becomes equal to or greater than the threshold value while the motor is rotating at the command rotation speed, the command rotation speed is The drive circuit is controlled so that a voltage for rotating the motor at high speed is applied to the motor, and the overheat state of the substrate is determined by the overheat state determination unit while the motor is rotating at high speed. In such a case, the application of the voltage for high-speed rotation to the motor is interrupted until the overheat state determination unit determines that the overheat state of the substrate is eliminated, and the command voltage is applied to the motor. Motor driving device of claim 1 for controlling the drive circuit so.   The overheat state determination unit determines that the substrate is in a heated state when the temperature of the substrate exceeds a first threshold temperature and reaches a second threshold temperature higher than the first threshold temperature, and the temperature of the substrate The motor driving device according to claim 1, wherein when the temperature becomes equal to or lower than the first threshold temperature, it is determined that the heating state has been eliminated.