JP2017184447A - Motor drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive unit capable of resetting quickly to rotation control at a target rotational speed, upon resolution of output voltage drop of a charge pump.SOLUTION: An FET driver 70 generates a FET gate signal for operating the FETs 44A, 44B, 44C, 44D, 44E, 44F of an inverter circuit 40, by using a step-up voltage generated by a charge pump 114, and outputs to the inverter circuit 40. The FET driver 70 stops output of the FET gate signal to the inverter circuit 40, when the step-up voltage generated by the charge pump 114 is less than a control voltage Vcc, otherwise resumes output of the FET gate signal to the inverter circuit 40.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a motor drive device.

  A control device for a brushless DC motor (hereinafter abbreviated as “motor”) used in a blower motor of a vehicle air conditioner causes the inverter circuit to generate a voltage having a duty ratio corresponding to the target rotational speed, and the generated voltage is supplied to the motor. It is applied to the coil.

  The inverter circuit generates a voltage to be applied to the motor coil by PWM (pulse width modulation) that modulates a power supply voltage by intermittently turning on a switching element such as an FET (field effect transistor). Since the voltage of the battery, which is the power source of the vehicle, is relatively high at about 12 V, the FET gate signal applied to the gate of the FET to turn on and off the FET constituting the inverter circuit is also required to have a corresponding height.

  In a motor drive device that drives a motor of a vehicle air conditioner, a control signal generated by a microcomputer or the like is amplified by a pre-driver to such an extent that the FET constituting the inverter circuit can perform a switching operation to generate an FET gate signal. Yes.

  Power is supplied to the pre-driver that amplifies the control signal via a charge pump. The charge pump boosts the control voltage Vcc and supplies it to the pre-driver.

  However, there is a case where the voltage boosted by the charge pump instantaneously decreases with respect to the voltage of the battery as the power source for some reason. For example, when a high-voltage pulse such as a surge is superimposed on the power supply voltage, if the power supply voltage further rises for some reason, the phenomenon that the boost of the charge pump cannot catch up with the change in the power supply voltage may occur. . As a result, the difference between the gate-source voltage of the FET of the inverter circuit and the threshold voltage of the FET of the inverter circuit based on the voltage of the FET gate signal generated by the pre-driver by the control voltage boosted by the charge pump is the FET of the inverter circuit. May be less than the drain-source voltage. In such a case, the FET of the inverter circuit operates in a saturation region, and there is a problem that heat generation of the FET becomes remarkable.

  Therefore, in the motor drive circuit, overheating of the FET of the inverter circuit is suppressed by the charge pump low voltage protection processing shown in FIG. 4 as an example. In step 400, the charge pump undervoltage protection and overvoltage protection are detected because the power supply voltage has increased. In step 402, the command for the rotational speed of the motor is set to 0, and in step 404, a duty ratio for reducing the rotational speed of the motor by PI control is calculated.

  In step 406, it is determined whether or not the actual rotational speed of the motor has become less than a predetermined rotational speed (for example, 244 rpm). If the determination is affirmative, the actual rotational speed of the motor is set to 0 in step 408 and step 410 is performed. In step 412, the duty ratio calculated by the PI control is set to 0. In step 412, the motor is turned off.

  In step 414, it is determined whether the power supply voltage decreases and the charge pump undervoltage protection and overvoltage protection can be released. If the determination is affirmative, the motor slow start activation is started in step 416 and the process is performed. Return.

  FIG. 5A shows an example of a change in the power supply voltage 200, a high voltage pulse 202, a charge pump low voltage protection execution status 204, an overvoltage protection execution status 206, a motor energization status 208, and a motor rotation speed. , (B) shows a charge pump undervoltage protection and overvoltage protection execution dialog 210, a charge pump voltage 214, a power supply current effective value 212 and a power supply voltage effective value 216 as a result of superimposing a high voltage such as a surge on the power supply voltage. (C) shows an example of an overvoltage protection execution dialog 218, a Hall element U-phase signal 220 for detecting the position of the rotor of the motor, an example of a power supply current effective value 212, and a power supply voltage effective value 216. Yes.

At time t _{1 in} FIG. 5, when the power supply voltage 200 is in a high voltage state, the charge pump undervoltage protection and overvoltage protection are turned on. In FIG. 5B, at time t ₁ , the rise of the charge pump voltage 214 indicating the boost of the charge pump is slower than the power supply voltage effective value 216. This phenomenon is because the charging of the capacitor in the charge pump cannot catch up with the rise of the power supply voltage effective value 216. As a result, at time t _1, the charge pump undervoltage protection is turned on together with the overvoltage protection, the rotational speed of the motor is reduced at a time t ₁ later.

At time t ₂ , the charge pump low voltage protection is to be released due to the rise of the charge pump voltage 214, but the overvoltage protection is continued because the power supply voltage 200 is still high. As a result, the energization of the motor is controlled so that the rotation speed of the motor becomes a rotation speed corresponding to a duty ratio of 30% indicated by the SI signal that is a command signal for overvoltage protection.

At time t ₃ , the power supply voltage decreases and the overvoltage protection is released. However, the SI signal having a duty ratio of 0% related to the charge pump low voltage protection is not canceled unless the rotational speed of the motor is less than 244 rpm. In FIG. 5A, since the high voltage pulse 202 such as a surge is superimposed on the power supply voltage, the duty ratio indicated by the SI signal is 30% as typified between the time t ₄ and the time t _5. The overvoltage protection is intermittently turned on. As a result, there has been a problem that the rotational speed of the motor does not become less than 244 rpm, which is the threshold for canceling the SI signal with a duty ratio of 0%, and it is not possible to shift to the rotational control at the original target rotational speed.

  In the process shown in FIG. 4, as shown in step 400, when the power supply voltage exceeds a predetermined value, charge pump undervoltage protection and overvoltage protection are executed. If the power supply voltage decreases, it is not necessary to execute at least overvoltage protection, but it is not possible to determine whether or not charge pump low-voltage protection is no longer necessary with only the power supply voltage. The necessity of charge pump low voltage protection requires comparing the difference between the gate-source voltage of the switching element and the threshold voltage of the switching element with the drain-source voltage of the switching element. However, in such a case, it is necessary to calculate the drain-source voltage from the power supply voltage and the gate-source voltage from the voltage of the FET gate signal. Since this calculation process is complicated, in the process of FIG. 4, when the rotational speed of the motor is less than a predetermined value of 244 rpm, it is considered that the gate-source voltage and the drain-source voltage are normalized, and the charge pump The low voltage protection is released.

  Patent Document 1 discloses a method for controlling an inverter circuit power supply that eliminates a voltage drop in the output of the charge pump by forcibly reducing the duty ratio when the voltage of the charge pump is reduced.

JP 2000-287455 A

  However, since the inverter circuit power supply control method described in Patent Document 1 generates a voltage having a duty ratio different from that of the command signal, there is a problem that the operation of a power load such as a motor is not performed as intended. It was.

  The present invention has been made in view of the above, and provides a motor drive device capable of quickly returning to rotation control at a target rotation speed indicated by a command signal when a voltage drop in the output of the charge pump is eliminated. Objective.

  In order to solve the above-described problem, the motor drive device according to claim 1 includes a plurality of switching elements each of which is controlled to be turned on / off by a supplied control signal, and is supplied according to an on / off state of the plurality of switching elements. A drive unit that converts the generated power supply voltage into a drive voltage to drive the motor, a booster circuit that boosts the control voltage and supplies the booster to the drive unit, and compares the boosted voltage generated by the booster circuit with the control voltage Based on the comparison between the control voltage comparison unit and the control voltage comparison unit, the supply of the control signal to the drive unit is stopped when the boosted voltage is less than the control voltage, and the boosted voltage is the control voltage A control unit that resumes the supply of the control signal to the drive unit in the above case.

  This motor drive device considers that the voltage drop of the output of the charge pump has occurred when the boosted voltage is less than the control voltage, and stops supplying the control signal to the drive unit. Further, the motor driving device assumes that the voltage drop of the output of the charge pump has been eliminated when the boosted voltage is equal to or higher than the control voltage, and resumes supplying the control signal to the driving unit. A comparison between the boosted voltage and the control voltage makes it possible to easily and quickly determine when the voltage drop in the output of the charge pump has been eliminated, and to quickly return to the rotation control at the target rotation speed indicated by the command signal.

  The motor drive device according to claim 2 is the motor drive device according to claim 1, wherein the switching element is a field effect transistor that is turned on when the control signal is applied to a gate.

  According to this motor drive device, the control unit can quickly return to the rotation control at the target rotation speed indicated by the command signal by restarting the output of the control signal applied to the gate of the switching element that is a field effect transistor. .

  The motor drive device according to claim 3 is the motor drive device according to claim 1 or 2, wherein the control unit stops supplying the control signal to the drive unit, so that the drive voltage is supplied to the motor. The control unit restarts the supply of the drive voltage to the motor by restarting the supply of the control signal to the drive unit.

  According to this motor drive device, on / off of power supply to the motor can be quickly switched by turning on / off the output of the control signal to the drive unit.

  The motor drive device according to claim 4 is the motor drive device according to any one of claims 1 to 3, wherein the control unit stops supplying the control signal to the drive unit. The processing related to the generation of the control signal is continued.

  According to this motor drive device, even when the voltage of the output of the charge pump decreases, by continuing the generation of the rectangular wave signal indicating the duty ratio based on the command signal, which is a process related to the generation of the control signal, When the voltage output from the charge pump is normalized, it is possible to immediately return to the control based on the command signal.

  The motor drive device according to claim 5 is the motor drive device according to any one of claims 1 to 4, wherein the booster circuit is a charge pump, and the control unit is a boosted voltage supplied from the charge pump. Is used to generate the control signal.

  According to this motor drive device, the control unit can generate a control signal having a potential for turning on and off the switching element by the electric power supplied from the booster circuit that is a charge pump.

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 flowchart which showed an example of the charge pump low voltage protection process of the motor drive device which concerns on embodiment of this invention. It is the flowchart which showed an example of the charge pump low voltage protection process in a prior art. (A) shows an example of changes in power supply voltage, high voltage pulse, charge pump low voltage protection execution status, overvoltage protection execution status, motor energization status, and motor rotation speed. An example of the power supply current effective value and the power supply voltage effective value as a result of superimposing the high voltage such as the pump undervoltage protection and overvoltage protection dialog, the charge pump voltage, and the surge on the power supply voltage is shown in FIG. 6 shows an example of the execution dialog, the U-phase signal of the Hall element for detecting the position of the rotor of the motor, the power supply current effective value, and the power supply voltage effective value.

  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. For example, the FETs 44A and 44D switch the power supplied to the U-phase coil 14U, the FETs 44B and 44E switch to the V-phase coil 14V, and the FETs 44C and 44F switch the power supplied to the W-phase coil 14W.

  The drains of the FETs 44 </ b> A, 44 </ b> B, 44 </ b> C are connected to the positive electrode of the vehicle-mounted battery 80 via the choke coil 82. The sources of the FETs 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, 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, an SI 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.

  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.

  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.

  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 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 that is a unit cycle of control of the protection priority determination unit 112 which 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.

  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 a power source, and outputs the final duty ratio to the FET driver 70. The FET driver generates an FET gate signal for controlling switching of the inverter circuit 40 based on the duty ratio output from the voltage correction unit 68 and outputs the FET gate signal to the inverter circuit 40. The inverter circuit 40 generates a voltage to be applied to the motor 52 by switching the FETs 44 </ b> A to 44 </ b> F according to the FET gate signal output from the FET driver 70.

  A boosted voltage is supplied to the FET driver 70 via a charge pump 114 that boosts the control voltage Vcc as necessary. The FET driver uses the boosted voltage supplied from the charge pump 114 as electric power, and generates an FET gate signal having a potential at which the FET constituting the inverter circuit 40 can perform a switching operation.

  The control voltage comparator 116 receives the boosted voltage from the charge pump 114 and the control voltage Vcc. The control voltage comparison unit 116 compares the control voltage Vcc and the boost voltage, and when the boost voltage is lower than the control voltage Vcc, a charge pump low voltage protection process described later is executed.

  FIG. 3 is a flowchart showing an example of charge pump low voltage protection processing of the motor drive device 20 according to the present embodiment. The flowchart shown in FIG. 3 starts when the boosted voltage is lower than the control voltage Vcc as shown in step 300. The charge pump low voltage protection is required when the difference between the gate-source voltage of the FET of the inverter circuit 40 and the threshold voltage of the FET of the inverter circuit 40 is less than or equal to the drain-source voltage of the FET of the inverter circuit 40. . In the present embodiment, when the boosted voltage is lower than the control voltage Vcc, it is assumed that the FET of the inverter circuit 40 may operate in a saturated region where heat generation is significant, and the processing shown in FIG. 3 is executed. .

  In step 302, the FET driver 70 turns off the energization of the motor 52 to eliminate overheating of the FET of the inverter circuit 40. In order to turn off the energization of the motor 52, the output of the FET gate signal from the FET driver 70 is stopped.

While the FET driver 70 stops outputting the FET gate signal, the calculation of the duty ratio by the command rotation number calculation unit 58, the PI control unit 66, and the voltage correction unit 68, which is a process related to the generation of the FET gate signal, is performed. By continuing, normal control based on a command from the air conditioner ECU 78 can be resumed immediately after the release of the charge pump low voltage protection.

  In step 304, the FET driver 70 determines whether the need for charge pump low voltage protection has been eliminated. Specifically, an affirmative determination is made when the boosted voltage output from the charge pump 114 becomes equal to or higher than the control voltage Vcc.

  In step 306, the FET driver 70 resumes outputting the FET gate signal. As a result, the inverter circuit 40 resumes control to rotate the motor 52 at a target rotational speed based on a command from the air conditioner ECU 78 by supplying power to the U-phase, V-phase, and W-phase coils of the stator 14 of the motor 52. Therefore, the process returns.

  As described above, in the present embodiment, when the boosted voltage is lower than the control voltage Vcc, and when the boosted voltage output from the charge pump 114 is lower than the control voltage Vcc, the FET of the inverter circuit 40 Considering that there is a possibility of operating in a saturation region where heat generation is significant, the output of the FET gate signal is stopped. Further, when the boosted voltage output from the charge pump 114 becomes equal to or higher than the control voltage Vcc, it is considered that the possibility that the FET of the inverter circuit 40 operates in the saturation region has been resolved, and the output of the FET gate signal is resumed. . With such a simplified process, charge pump low voltage protection can be initiated and released quickly.

  In the present embodiment, as described above, the necessity of charge pump low voltage protection is determined by comparing the boosted voltage output from the charge pump 114 and the control voltage Vcc. When the FET of the inverter circuit 40 that requires charge pump low-voltage protection operates in a saturation region, the difference between the gate-source voltage of the FET of the inverter circuit 40 and the threshold voltage of the FET of the inverter circuit 40 is the inverter circuit. This is the case when it is less than the drain-source voltage of 40 FETs.

  For example, it further comprises a sensor for detecting the voltage of the FET gate signal and a sensor for detecting the power supply voltage, and the gate-source voltage of the FET of the inverter circuit 40 is determined from the voltage of the FET gate signal, and the FET of the inverter circuit 40 is determined from the power supply voltage. And the difference between the gate-source voltage of the FET of the inverter circuit 40 and the threshold voltage of the FET of the inverter circuit 40 is less than the drain-source voltage of the FET of the inverter circuit 40. It may be determined whether or not.

  Further, the voltage of the FET gate signal is correlated with the gate-source voltage of the FET of the inverter circuit 40, and the power supply voltage is correlated with the drain-source voltage of the FET of the inverter circuit 40. You may judge.

  For example, when the difference between the voltage of the FET gate signal and the predetermined voltage becomes equal to or lower than the power supply voltage, the charge pump low voltage protection is started. When the difference between the voltage of the FET gate signal and the predetermined voltage exceeds the power supply voltage, the charge pump low voltage protection is released. The predetermined voltage is based on the threshold voltage of the FET of the inverter circuit 40.

  Alternatively, charge pump low-voltage protection is started when the difference between the power supply voltage and the voltage of the FET gate signal is equal to or higher than the second predetermined voltage. Then, when the difference between the power supply voltage and the voltage of the FET gate signal becomes less than the second predetermined voltage, the charge pump low voltage protection is canceled. The second predetermined voltage is based on the threshold voltage of the FET of the inverter circuit 40 similarly to the above-described predetermined voltage, and is a value obtained by inverting the sign of the above-described predetermined voltage.

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 ... FET, 52 ... motor, 54 ... comparator, 56 ... actual rotation speed calculation unit, 58 ... command rotation speed calculation , 60 ... standby circuit, 62 ... main power supply energization part, 66 ... PI control part, 66I ... deviation integration part, 66P ... deviation proportional part, 68 ... voltage correction part, 70 ... FET driver, 78 ... air conditioner ECU, 80 ... Battery: 82 ... Choke coil, 84A, 84B ... Smoothing capacitor, 86 ... Logical sum circuit, 88 ... Forced 500rpm Command part, 94 ... Current detection part, 94A ... Shunt resistance, 94B ... Amplifier, 96 ... Overload judgment value output part, 98 ... Overload judgment part, 100 ... Overcurrent judgment value output part, 102 ... Overcurrent judgment part, DESCRIPTION OF SYMBOLS 104 ... Overheat determination value output part, 106 ... Overheat state determination part, 108 ... Overvoltage determination value output part, 110 ... Overvoltage determination part, 112 ... Protection priority order determination part, 114 ... Charge pump, 116 ... Control voltage comparison part, 200 ... power supply voltage, 202 ... high voltage pulse, 204 ... charge pump low voltage protection execution status, 206 ... overvoltage protection execution status, 208 ... motor energization status, 210 ... undervoltage protection and overvoltage protection execution dialog, 212 ... power supply current effective value , 214 ... Charge pump voltage, 216 ... Power supply voltage effective value, 218 ... Overvoltage protection execution dialog, 220 ... U phase signal, RT ... Chip thermist , Vcc ... control _{voltage, t 1, t 2, t} 3, t 4, t 5 ... Time

Claims (5)

A plurality of switching elements that are each controlled to be turned on and off by a supplied control signal, and a drive unit that drives the motor by converting the supplied power supply voltage into a drive voltage according to the on / off state of the plurality of switching elements;
A booster circuit that boosts a control voltage and supplies the boosted voltage to the drive unit;
A control voltage comparison unit that compares the boosted voltage generated by the booster circuit with the control voltage;
Based on the comparison in the control voltage comparison unit, the supply of the control signal to the drive unit is stopped when the boosted voltage is less than the control voltage, and the control signal when the boosted voltage is equal to or higher than the control voltage. A control unit for restarting the supply of the drive unit to
A motor driving device.   The motor driving device according to claim 1, wherein the switching element is a field effect transistor that is turned on when the control signal is applied to a gate.   The control unit stops supply of the control signal to the drive unit to stop supply of the drive voltage to the motor, and the control unit resumes supply of the control signal to the drive unit. The motor drive device according to claim 1, wherein supply of the drive voltage to the motor is resumed by the operation.   4. The motor drive device according to claim 1, wherein the control unit continues the process related to the generation of the control signal even when the supply of the control signal to the drive unit is stopped. 5. The booster circuit is a charge pump;
The motor drive device according to claim 1, wherein the control unit generates the control signal using a boosted voltage supplied from the charge pump.