JP2017201863A - Motor drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive device capable of smoothly controlling a rotation of a motor even when a duty ratio is large.SOLUTION: A PI control unit 66 calculates a duty ratio from a rotational speed command value and an actual rotational speed and outputs a calculated duty ratio. A voltage correction unit 68 corrects the duty ratio according to a power supply voltage when the duty ratio output from the PI control unit 66 is 90% or less, and, when the duty ratio output from the PI control unit 66 is greater than 90% and the power supply voltage is equal to or lower than the threshold voltage, the duty ratio set to 85% is corrected according to the power supply voltage, and causes an inverter circuit 40 to generate voltages according to the corrected duty ratios.SELECTED DRAWING: Figure 3

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. Furthermore, a power load such as an electric power steering is also connected. The battery voltage may fluctuate due to the influence of these devices connected to the battery and the power load.

  The voltage fluctuation of the battery as the power source affects the rotation speed of the motor. The electric power supplied to the motor is generated by PWM (Pulse Width Modulation) that generates a pulse-shaped waveform voltage by turning on and off the switching element according to the duty ratio based on the command value of the battery voltage. When the PWM duty ratio is constant, that is, when the motor is rotated at a constant speed, if the voltage of the battery fluctuates, the effective voltage of the power supplied to the motor fluctuates. This is because if the duty ratio is constant before and after the fluctuation of the battery voltage, the voltage generated by the PWM changes according to the fluctuation of the battery voltage. As a result, it becomes difficult to keep the rotation speed of the motor constant.

  In the control of the rotational speed of the motor by PWM, voltage correction for controlling the duty ratio of the voltage applied to the terminal of the motor winding in accordance with the fluctuation of the voltage of the power supply is performed. In the voltage correction, control is executed to lower the duty ratio when the battery voltage becomes higher and to increase the duty ratio when the battery voltage becomes lower.

  However, when voltage correction is performed when the duty ratio exceeds 90%, for example, by rotating the motor at high speed, a phenomenon is observed in which control hunting occurs and motor rotation becomes irregular. For example, when the duty ratio according to the command value exceeds 90% and the battery voltage is low, it is necessary to further increase the duty ratio by voltage correction. When the duty ratio becomes extremely large, the interval at which the switching element is turned on / off becomes extremely short. In such a case, the switching element cannot output a pulse in accordance with the voltage-corrected duty ratio, which may hinder the control of the rotation speed of the motor.

  Patent Documents 1 and 2 disclose motor control devices that do not perform voltage correction when the duty ratio is large.

JP 2013-36572 A JP 2012-60798 A

  However, as in the inventions described in Patent Document 1 and Patent Document 2, if the voltage correction is not performed when the duty ratio is large, an excessive current may flow to the motor when the power supply voltage suddenly increases. is there. When the motor current becomes excessive, overcurrent protection is performed and the rotation of the motor is stopped, which hinders the operation of equipment such as an air conditioner that uses the motor as a drive source.

  The present invention has been made in view of the above, and an object of the present invention is to provide a motor driving device capable of smoothly controlling the rotation of the motor even when the duty ratio is large.

  In order to solve the above problem, a motor driving device according to claim 1, a driving unit that generates a voltage for driving a motor by pulse width modulation, a voltage detection unit that detects a power supply voltage, and an output of pulse width modulation. When the duty ratio exceeds the first threshold and the voltage detected by the voltage detector is equal to or lower than a predetermined value, pulse width modulation is performed to reduce the output duty ratio to a second threshold lower than the first threshold. And a control unit that controls the drive unit so that voltage compensation control is performed to suppress rotation fluctuations of the motor when the power supply voltage fluctuates.

  This motor drive device has a pulse width that reduces the output duty ratio to a second threshold value that is lower than the first threshold value when the output duty ratio of the pulse width modulation exceeds the first threshold value and the power supply voltage is not more than a predetermined value. By reducing the output duty ratio that is modulated, there is a margin in the operation of the switching element of the drive unit, and the rotation of the motor can be controlled smoothly.

  In addition, the motor drive device can smoothly control the rotation of the motor by executing voltage compensation control that suppresses the rotation fluctuation of the motor when the power supply voltage fluctuates.

  According to a second aspect of the present invention, in the motor driving device according to the first aspect, when the output duty ratio is equal to or lower than the first threshold value, the control unit performs pulse width modulation based on the output duty ratio. In addition, the drive unit is controlled so that the voltage compensation control is performed.

  According to this motor drive device, by executing voltage compensation control when the output duty ratio is equal to or less than the first threshold, when the power supply voltage fluctuates, the rotation fluctuation of the motor is suppressed and the motor rotation is smoothly performed. Can be controlled.

  According to a third aspect of the present invention, in the motor driving device according to the first or second aspect, the control unit is configured such that the output duty ratio exceeds the first threshold and the voltage detected by the voltage detection unit is the same. The voltage compensation control is stopped when the predetermined value is exceeded, and the voltage compensation control is resumed when the output duty ratio becomes less than the second threshold value.

  This motor drive device suppresses control hunting that tends to occur when the duty ratio is large by stopping the voltage compensation control when the output duty ratio exceeds the first threshold and the power supply voltage exceeds the threshold voltage. In addition, this motor drive device suppresses the rotation fluctuation of the motor when the power supply voltage fluctuates by resuming the voltage compensation control when the output duty ratio becomes less than the second threshold value, thereby rotating the motor. Can be controlled smoothly.

  The motor drive device according to claim 4 is the motor drive device according to any one of claims 1 to 3, wherein the voltage compensation control is performed when the voltage detected by the voltage detector increases. The ratio is decreased according to the voltage increase, and when the voltage detected by the voltage detection unit is decreased, the output duty ratio is increased according to the voltage decrease.

  According to this motor drive device, by correcting the output duty ratio according to the voltage of the power supply, it is possible to suppress the rotational speed fluctuation at the time of voltage fluctuation.

  According to a fifth aspect of the present invention, in the motor drive device according to any one of the first to fourth aspects, the motor drive device includes a rotational speed detection unit that detects a rotational speed of the motor, and the control unit is configured to perform a target rotation indicated by a command value The output duty ratio is calculated so as to eliminate the deviation between the speed and the actual rotational speed of the motor detected by the rotational speed detector.

  According to this motor drive device, the actual rotation speed of the motor is calculated by calculating the duty ratio based on the command value by PI control that eliminates the deviation between the rotation speed indicated by the command value and the actual rotation speed of the motor. It is possible to control the rotational speed of the motor in consideration.

It is the schematic which shows an example of a 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 a functional block diagram of the control part centering on PI control part and voltage correction | amendment part of the motor drive device which concerns on embodiment of this invention. It is the flowchart which showed an example of the voltage correction control in the motor drive device which concerns on embodiment of this invention.

  FIG. 1 is a schematic diagram illustrating an example of a configuration of a motor unit 10 using a motor driving 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. 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 rotational speed calculation unit 58 calculates a target rotational speed based on an instruction from the air conditioner ECU 78 or the like. In the present embodiment, the target rotation speed is approximately 1000 to 5000 rpm.

  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 duty ratio based on the calculation result by the PI control unit 66 according to the voltage of the battery 80 as a power source. Such correction suppresses fluctuations in the rotational speed of the motor 52 when the power supply voltage varies.

  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 20 according to the control of the standby circuit 60. Further, the main power supply energizing unit 62 issues a command to the forced 500 rpm command unit 88 via the OR circuit 86 when the motor 52 is started, that is, when the motor 52 is rotated from a rotation speed of 0 rpm. The forced 500 rpm command unit 88 controls the command rotational speed calculation unit 58 so that the target rotational speed becomes 500 rpm at a predetermined time when the motor 52 is started, and the command rotational speed calculation unit 58 performs PI control on a signal related to 500 rpm. The data is output to the unit 66. The predetermined time is 500 to 1000 milliseconds as an example.

  After the predetermined time has elapsed, the control to the command rotational speed calculation unit 58 by the forced 500 rpm command unit is finished, and the command rotational speed calculation unit 58 outputs a signal related to the target rotational speed calculated based on an instruction from the air conditioner ECU 78. Output to the PI controller 66.

  When power is supplied through the standby circuit 60 and the main power supply energization unit 62, the energization control drive waveform determination unit 64 drives the drive waveform of the voltage applied to the coil of the stator 14 based on the signal from the voltage correction unit 68. To decide.

  The FET driver 70 generates a PWM signal for controlling switching of the inverter circuit 40 based on the drive waveform determined by the energization control drive waveform determination unit 64 and outputs the PWM signal to the inverter circuit 40.

  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 the present embodiment is, for example, an NTC (Negative Temperature Coefficient) thermistor whose resistance 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 the output terminal of the voltage dividing circuit constituted by the chip thermistor RT. The voltage output from the output terminal of the voltage dividing circuit constituted by the chip thermistor RT is compared with the overheat determination value output from the overheat determination value output unit 104 in the overheat state determination unit 106, and the output voltage is equal to or less than the overheat determination value. In this case, the command rotational speed calculation unit 58 is controlled so that the target rotational speed is forcibly set to 0 rpm. As described above, since the chip thermistor RT according to the present embodiment is a type in which the resistance decreases as the temperature rises, the voltage output from the output terminal of the voltage dividing circuit constituted by the chip thermistor RT is the temperature It shall decrease as the rise of The overheat state determination unit 106 determines that the circuit is overheated when the voltage output from one end of the chip thermistor RT is equal to or less than the overheat determination value. The overheat determination value varies depending on the element mounted on the substrate, the position of the chip thermistor RT, and the like. As an example, the overheat determination value is a voltage output from a voltage dividing circuit constituted by the chip thermistor RT at 145 ° C.

  Further, a current detector 94 for detecting the current of the inverter circuit 40 is provided between the source of each of the inverter FETs 44D, 44E, and 44F and the battery 80. The current detector 94 detects a potential difference between both ends of the shunt resistor 94A having a resistance value of about 0.2 mΩ to several Ω and the shunt resistor 94A that changes according to the current of the inverter circuit 40 and amplifies the detected potential difference signal. Amplifier 94B. The signal output from the amplifier 94B is input to the overload determination unit 98 and the overcurrent determination unit 102, respectively. The overcurrent determination unit 102 compares the signal output from the amplifier 94B with the overcurrent determination value output from the overcurrent determination value output unit 100. When the signal output from the amplifier 94B is equal to or greater than the overcurrent determination value, The overcurrent detection signal is output to the protection priority determination unit 112. The overload determination unit 98 compares the signal output from the amplifier 94B with the overload determination value output from the overload determination value output unit 96, and when the signal output from the amplifier 94B is equal to or greater than the overload determination value. Sends a command to the forced 500 rpm command section 88 via the OR circuit 86 to control the motor 52 to forcibly reduce the rotational speed of the motor 52 to a predetermined rotational speed of 500 rpm.

  When the motor 52 is determined to be in an overload state and the rotation speed of the motor 52 is set to 500 rpm, the current value detected by the current detection unit 94 (the amplified value of the potential difference at both ends of the shunt resistor 94A that changes according to the current value) becomes the overload determination value. The rotational speed of the motor 52 is controlled to 500 rpm until it falls below. After the current value detected by the current detector 94 falls below the overload determination value, the voltage applied to the coil of the stator 14 is set so that the motor 52 rotates at the target rotational speed calculated by the command rotational speed calculator 58. Control.

  In the present embodiment, the overcurrent determination value is a value that exceeds the overload determination value, and current that must be de-energized to the motor 52 by stopping the generation of voltage by the inverter circuit 40 for circuit protection. Value. Since the specific values of the overcurrent determination value and the overload determination value depend on the specifications of the motor 52, they are specifically determined for each motor specification through simulation and experiment at the time of design.

  Connected between the choke coil 82 and the inverter circuit 40 is an overvoltage determination unit 110 that detects the power supply voltage and compares the value of the power supply voltage with the overvoltage determination value output from the overvoltage determination value output unit 108. . The overvoltage determination unit 110 outputs an overvoltage detection signal to the protection priority determination unit 112 when the power supply voltage is equal to or higher than the overvoltage determination value.

  The protection priority determination unit 112 rotates the motor 52 or stops the rotation of the motor 52 based on the overvoltage detection signal output from the overvoltage determination unit 110 and the overcurrent detection signal output from the overcurrent determination unit 102. The FET driver 70 is controlled so that the

  For example, when the overcurrent detection signal is not output and the overvoltage detection signal is output, the protection priority determination unit 112 rotates the motor 52 at a predetermined rotation speed in order to relax the power supply voltage that is too high. The forced ON state is continued for one control cycle (10 ms as an example) that is a unit cycle of control of the protection priority determination unit 112 that is a kind of processor.

  When the overcurrent detection signal is output, the FET driver 70 is controlled so as to stop the energization of the motor 52 in order to stop the rotation of the motor 52 even if the overvoltage detection signal is output. The elements constituting the inverter circuit 40 and the like are protected. In order to immediately stop energization, interrupt processing or the like is used as an example. After the overcurrent detection signal is output, the overcurrent OFF state in which the rotation of the motor 52 is stopped is continued for a predetermined time longer than the aforementioned one control cycle or one control cycle. The predetermined time is a predetermined positive integer multiple of one control cycle.

  FIG. 3 is a functional block diagram of the control unit 30 centering on the PI control unit 66 and the voltage correction unit 68 of the motor drive device 20 according to the present embodiment. Unlike FIG. 2, the configuration related to calculation of the duty ratio by PI control and voltage correction is highlighted, excluding the configuration related to overcurrent protection and overvoltage protection.

  The PI controller 66 determines the actual rotational speed from the target rotational speed calculated by the command rotational speed calculator 58 based on the rotational signal of the Hall element 12B and the actual rotational speed calculated by the actual rotational speed calculator 56. The duty ratio of the voltage applied to the coil of the stator 14 when changing to is calculated by PI control. The voltage correction unit 68 corrects the duty ratio based on the calculation result by the PI control unit 66 according to the voltage of the battery 80 that is the power source detected by the power supply voltage detection unit 32, and sets the final duty ratio to the FET driver 70. Output. The FET driver outputs a PWM signal for controlling switching of the inverter circuit 40 based on the duty ratio output from the voltage correction unit 68 and the drive waveform determined by the energization control drive waveform determination unit 64 shown in FIG. It is generated and output to the inverter circuit 40. The inverter circuit 40 switches the inverter FETs 44 </ b> A to 44 </ b> F according to the PWM signal output from the FET driver 70 and generates a voltage to be applied to the motor 52.

  Hereinafter, the operation and effect of the motor drive device 20 according to the present embodiment will be described. FIG. 4 is a flowchart showing an example of voltage correction control in the motor drive device 20 according to the present embodiment. In step 400, it is determined whether or not the duty ratio output from the PI controller 66 has exceeded the first threshold value of 90%. If the determination is negative, the duty ratio is corrected in accordance with the voltage of the battery 80 in step 402. The voltage correction is performed to suppress fluctuations in the rotational speed of the motor 52 when the voltage of the battery 80 fluctuates, and the process returns. The first threshold value is 90% as an example, and specific numerical values are specifically determined by a test of an actual machine or the like according to the specifications of the motor driving device 20 and the motor 52.

  If the determination in step 400 is affirmative, it is determined in step 404 whether or not the voltage of the battery 80 is in a low voltage state below the threshold voltage. As an example, the threshold voltage is 70 to 75% of the nominal voltage of the battery 80.

  In the case of negative determination in step 404, it is determined in step 406 whether or not the duty ratio has already been set to the second threshold value of 85% in step 414 described later. The second threshold is a value lower than the first threshold, and is a duty ratio that allows the inverter circuit 40 to operate the switching element with a margin even after voltage correction. In the present embodiment, the second threshold value is set to 85%, which is just an example, and specific numerical values are specifically determined by tests on actual machines or the like according to the specifications of the motor driving device 20 and the motor 52. . The determination as to whether or not the duty ratio has already been set to 85%, which is the second threshold, is made by, for example, determining whether the flag turned on when the duty ratio is set to 85%, which is the second threshold, in step 414. Judge by presence or absence.

  If the determination in step 406 is affirmative, the setting of the duty ratio of 85% is canceled in step 408, and the procedure proceeds to step 410. If the determination in step 406 is negative, the procedure proceeds to step 410.

  In step 410, power correction is turned off, and in step 412, it is determined whether the duty ratio output from the PI controller 66 is less than the second threshold value of 85%.

  If the determination in step 412 is affirmative, voltage correction for correcting the duty ratio according to the voltage of the battery 80 is performed in step 402, and the process is returned. If the determination in step 412 is negative, the procedure returns to step 404 to determine whether or not the voltage of the battery 80 is in a low voltage state.

  If the determination in step 404 is affirmative, the duty ratio is set to 85% that is the second threshold value in step 414. In step 414, when the duty ratio is set to the second threshold value of 85%, a flag indicating that the setting is completed is turned on. In step 414, the duty ratio may be set to be equal to or less than the second threshold value.

  In step 416, voltage correction is performed to correct the duty ratio, which is 85% corresponding to the second threshold, in accordance with the voltage of the battery 80, thereby suppressing fluctuations in the rotation speed of the motor 52 when the voltage of the battery 80 fluctuates. In step 418, it is determined whether the duty ratio output from the PI control unit 66 is less than 85%, which is the second threshold value.

  If the determination in step 418 is negative, the procedure returns to step 404 to determine whether or not the voltage of the battery 80 is in a low voltage state. If the determination in step 418 is affirmative, the setting of the duty ratio of 85% is canceled in step 420, and the control returns to the control for generating the voltage to be applied to the motor 52 based on the duty ratio output from the PI control unit 66. In step 402, voltage correction is performed to correct the duty ratio in accordance with the voltage of the battery 80, and the process returns.

  As described above, in the present embodiment, the duty ratio of the voltage applied to the motor 52 when the duty ratio output from the PI control unit 66 exceeds the first threshold and the battery 80 is in the low voltage state. Is set to a second threshold value lower than the first threshold value to turn on voltage correction. At the duty ratio corresponding to the second threshold value that is lower than the first threshold value, the interval at which the inverter FETs 44A to 44F that are switching elements are switched is longer than that when the duty ratio is the first threshold value. There is more margin than when the duty ratio exceeds the first threshold. Even when the duty ratio is made larger than the second threshold value by voltage correction when the battery 80 is in a low voltage state, the inverter circuit 40 can easily output pulses according to the duty ratio after voltage correction, and the motor 52. Control hunting can be prevented.

  In the present embodiment, when the duty ratio output from the PI control unit 66 exceeds the first threshold and the battery 80 is in a low voltage state, the duty ratio output from the PI control unit 66 is the second. Unless it falls below the threshold value, the duty ratio related to the operation of the switching element is set to the second threshold value, and the voltage correction for correcting the duty ratio corresponding to the second threshold value according to the voltage of the battery 80 is continued.

  When the battery 80 is in a low voltage state, even when the voltage of the battery 80 as a power supply suddenly increases due to a surge or the like, it is possible to prevent the motor current from becoming excessive by executing voltage correction. As a result, a situation where overcurrent protection is executed and the rotation of the motor 52 is stopped can be avoided, and smooth control of the rotation of the motor 52 can be continued.

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, 30 ... control unit, 32 ... power supply voltage detection unit, 40 ... inverter circuit, 44A, 44B, 44C, 44D, 44E, 44F ... inverter FET, 52 ... motor, 54 ... comparator, 56 ... actual rotation speed calculation section, 58 ... command rotation speed calculation section, 60 ... standby circuit, 62 ... main power supply energization section, 64 ... energization control drive waveform determination section, 66 ... PI control section, 66I ... deviation integration section, 66P ... Deviation proportional part, 68 ... Voltage correction part, 70 ... FET driver, 78 ... Air conditioner ECU, 80 ... Battery, 82 ... Chalk carp 84A ... smoothing capacitor, 86 ... OR circuit, 88 ... forced 500 rpm command unit, 94 ... current detection unit, 94A ... shunt resistor, 94B ... amplifier, 96 ... overload judgment value output unit, 98 ... overload judgment unit, DESCRIPTION OF SYMBOLS 100 ... Overcurrent determination value output part, 102 ... Overcurrent determination part, 104 ... Overheat determination value output part, 106 ... Overheat state determination part, 108 ... Overvoltage determination value output part, 110 ... Overvoltage determination part, 112 ... Protection priority Judgment unit, RT ... Chip thermistor

Claims (5)

A drive unit for generating a voltage for driving the motor by pulse width modulation;
A voltage detector for detecting a power supply voltage;
Pulse that reduces the output duty ratio to a second threshold lower than the first threshold when the output duty ratio of the pulse width modulation exceeds the first threshold and the voltage detected by the voltage detector is equal to or lower than a predetermined value. A control unit for controlling the driving unit so that voltage compensation control is performed to suppress rotation fluctuation of the motor when width modulation is performed and the power supply voltage fluctuates;
A motor driving device.   2. The control unit controls the driving unit such that when the output duty ratio is equal to or less than the first threshold, pulse width modulation is performed by the output duty ratio and the voltage compensation control is performed. The motor drive device described.   The control unit stops the voltage compensation control when the output duty ratio exceeds the first threshold and the voltage detected by the voltage detection unit exceeds the predetermined value, and the output duty ratio is The motor driving device according to claim 1, wherein the voltage compensation control is resumed when the voltage becomes less than the second threshold value.   The voltage compensation control reduces the output duty ratio in response to an increase in voltage when the voltage detected by the voltage detection unit increases, and outputs the output when the voltage detected by the voltage detection unit decreases. The motor drive device according to claim 1, wherein the duty ratio is increased in accordance with a decrease in voltage. A rotation speed detection unit for detecting the rotation speed of the motor;
The said control part calculates the said output duty ratio so that the deviation of the target rotational speed which command value shows, and the actual rotational speed of the said motor detected by the said rotational speed detection part may be eliminated. A motor driving apparatus according to claim 1.