JP2016167970A - Motor controller and electrically-driven power steering device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller and electrically-driven power steering device having the same, capable of completely protection of a motor opening switch with high reliability in connection with temperatures.SOLUTION: The motor controller includes: a control part which detects assist states of sensors and an inverter, turns on/off control of the inverter according to a detection result and detects presence/absence of abnormality; a motor speed detection part for detecting a motor speed; an energy arithmetic part for calculating a motor counter electromotive voltage and energy of a regenerative current by a data table on the basis of a revolution speed; and a determination part for turning off all FETs of a motor opening switch when energy is compared to a safe operating area of FET and the energy continues for a predetermined time in an area of the safe operating area, and turns off control of the inverter when a state detection part detects some abnormality.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a semiconductor switching element connected to an inverter that drives a motor from the energy (electric power) and temperature of regenerative electric power (determined by a counter electromotive voltage and a regenerative current) that accompanies the rotation of the motor when the motor is rotated by an external force. For example, the motor open switch composed of FET) is turned off when the switching loss caused by regenerative power when the switching loss is within the safe operating range for a predetermined time or less continues for a predetermined time, thereby securely switching the semiconductor switching element. The present invention relates to a motor control device to be protected and an electric power steering device equipped with the motor control device.

  The electric power steering device applies an assist force by a motor to a vehicle steering system based on a current command value calculated based on at least a steering torque, and is driven and controlled by an inverter formed of a bridge circuit of semiconductor switching elements. .

  There is an electric power steering device (EPS) as a device equipped with a motor control device, and the electric power steering device gives a steering assist force (assist force) to the steering mechanism of the vehicle by the rotational force of the motor. The driving force of the motor controlled by the supplied electric power is applied to the steering shaft or the rack shaft by a transmission mechanism such as a gear. Such a conventional electric power steering apparatus performs feedback control of the motor current in order to accurately generate the torque of the steering assist force. In feedback control, the motor applied voltage is adjusted so that the difference between the steering assist command value (current command value) and the motor current detection value is small. The adjustment of the motor applied voltage is generally performed by PWM (pulse width). This is done by adjusting the duty of modulation) control.

  The general configuration of the electric power steering apparatus will be described with reference to FIG. 6b is further connected to the steering wheels 8L and 8R via hub units 7a and 7b. Further, the column shaft 2 is provided with a torque sensor 10 for detecting the steering torque of the handle 1 and a steering angle sensor 14 for detecting the steering angle θ, and the motor 20 for assisting the steering force of the handle 1 is provided with the reduction gear 3. Are connected to the column shaft 2 via The control unit (ECU) 100 that controls the electric power steering apparatus is supplied with electric power from the battery 13 and also receives an ignition key signal via the ignition key 11. The control unit 100 calculates a current command value of an assist (steering assist) command based on the steering torque Th detected by the torque sensor 10 and the vehicle speed Vel detected by the vehicle speed sensor 12, and compensates the current command value. The current supplied to the EPS motor 20 is controlled by the voltage control command value Vref subjected to.

  The steering angle sensor 14 is not essential and may not be provided, and the steering angle can be obtained from a rotation sensor such as a resolver connected to the motor 20.

  The control unit 100 is connected to a CAN (Controller Area Network) 40 that transmits and receives various types of vehicle information, and the vehicle speed Vel can also be received from the CAN 40. Further, the control unit 100 can be connected to a non-CAN 41 that exchanges communication, analog / digital signals, radio waves, and the like other than the CAN 40.

  The control unit 100 is mainly composed of a CPU (including an MPU, MCU, etc.). FIG. 2 shows general functions executed by a program inside the CPU.

  The control unit 100 will be described with reference to FIG. 2. The steering torque Th detected by the torque sensor 10 and the vehicle speed Vel detected by the vehicle speed sensor 12 (or from the CAN 40) are a current command for calculating a current command value Iref1. The value is input to the value calculation unit 101. The current command value calculation unit 101 calculates a current command value Iref1, which is a control target value of the current supplied to the motor 20, using an assist map or the like based on the input steering torque Th and vehicle speed Vel. The current command value Iref1 is input to the current limiting unit 103 via the adding unit 102A, and the current command value Irefm whose maximum current is limited is fed back to the subtracting unit 102B, and the deviation I (= Irefm−Im) from the motor current value Im. ) And the deviation I is input to the PI control unit 104 for improving the characteristics of the steering operation. The voltage control command value Vref whose characteristics are improved by the PI control unit 104 is input to the PWM control unit 105, and the motor 20 is further PWM driven via the inverter 106. The current value Im of the motor 20 is detected by the motor current detector 107 and fed back to the subtraction unit 102B. The inverter 106 is composed of an FET bridge circuit as a semiconductor switching element.

  A rotation sensor 21 such as a resolver is connected to the motor 20, a motor rotation angle θ is output from the rotation sensor 21, and a motor speed ω is calculated by a motor speed calculation unit 22.

  Further, the compensation signal CM from the compensation signal generation unit 110 is added to the addition unit 102A, and the compensation of the steering system system is performed by adding the compensation signal CM, thereby improving the convergence property, the inertia property, and the like. ing. Compensation signal generation section 110 adds self-aligning torque (SAT) 113 and inertia 112 by addition section 114, and further adds convergence 111 to the addition result by addition section 115, and compensates the addition result of addition section 115. The signal CM is used.

  When the motor 20 is a three-phase brushless motor, the details of the PWM control unit 105 and the inverter 106 are configured as shown in FIG. 3, for example, and the PWM control unit 105 sets the voltage control command value Vref to a three-phase according to a predetermined formula. Duty calculation unit 105A that calculates PWM duty values D1 to D6 for minutes, and a gate drive unit that drives the gates of FETs as drive elements with PWM duty values D1 to D6, and ON / OFF by compensating for dead time 105B. The inverter 106 is formed of a three-phase bridge (FET1 to FET6) of FETs as semiconductor switching elements, and drives the motor 20 by being turned ON / OFF by PWM duty values D1 to D6. In addition, a motor relay 23 for supplying power (ON) or shutting off (OFF) is connected to each phase of the power supply line between the inverter 106 and the motor 20.

  For such an electric power steering apparatus, an unexpected situation may be encountered when a system abnormality is detected (for example, disconnection of a torque sensor, a short circuit accident of a motor control stage FET, etc.). As a countermeasure in this case, the assist control of the electric power steering apparatus is immediately stopped, and the connection between the drive control system and the motor is cut off with the highest priority.

  In general, as shown in FIG. 3, a motor relay 23 for supplying / cutting off the motor current is interposed between the motor 20 and an inverter 106 that controls a current flowing through the motor 20. An inexpensive contact relay is used as the motor relay 23, and the contact current is electromagnetically opened to cut off the current flowing through the motor 20 in a hardware manner (for example, Japanese Patent Application Laid-Open No. 2005-199746). Patent Document 1)).

  However, in recent years, a contactless semiconductor switching element (analog switch), for example, a motor open switch composed of an FET, is used instead of a contacted electromagnetic motor relay in order to reduce the size, improve reliability, and reduce costs. Has been replaced. However, if it is impossible to continue the assist due to a system error, if the motor is rotating even if the inverter is stopped, the motor regenerative power will be within the safe operating area of the motor opening switch if the motor opening switch is turned off while the motor is rotating. The motor opening switch may be damaged or destroyed.

  As an apparatus using a semiconductor switching element for a motor relay, for example, there is one disclosed in JP2013-183462A (Patent Document 2). In the device of Patent Document 2, when a failure of the power converter (inverter) is detected, the drive of the inverter is stopped, the first power supply relay is turned off, and the second power supply relay is turned on. When the drive of the inverter is stopped and the motor is rotated by an external force and a regenerative voltage is generated, the regenerative voltage is supplied from the inverter through the second power supply relay in the ON state and the parasitic diode of the first power supply relay. ) Is regenerated.

  In the electric power steering device, it is necessary to pay particular attention to the element destruction due to the deviation of the safe operation area of the semiconductor element due to the generation of the back electromotive force accompanying the motor rotation and the switching loss when the motor relay is turned off by the motor regenerative current. It is strongly desired that countermeasures against destruction be carried out inexpensively and reliably without adding hard parts as much as possible.

  In Japanese Patent No. 5120041 (Patent Document 3), when all the phase opening means (motor relays) are opened and a voltage is applied to only one specific phase, the phases other than the specific phase are disclosed. When a terminal voltage based on the application of voltage is detected, it is determined that a short circuit failure has occurred in the phase opening means provided in the specific phase. Therefore, the apparatus of Patent Document 3 detects a failure of the phase opening means itself and does not actively protect the device of the semiconductor switching element.

JP 2005-199746 A JP 2013-183462 A Japanese Patent No. 5120041 JP 2011-239489 A JP 2008-141868 A

  As a motor device for protecting a semiconductor switching element, those shown in Japanese Patent Application Laid-Open No. 2011-239489 (Patent Document 4) and Japanese Patent Application Laid-Open No. 2008-141868 (Patent Document 5) have been proposed. In Patent Document 1, the switching element is protected by performing PWM control of OFF processing from detection of a circuit abnormality for a predetermined time (during avalanche energy release). Further, in Patent Document 5, in the OFF process from abnormality detection, the threshold value is relatively set to the high rotation side when the motor rotation speed and the motor temperature are on the low temperature side in the circuit interruption condition.

  However, in the device of Patent Document 4, when a predetermined time has elapsed after turning off each semiconductor switching element of the inverter, the semiconductor switching element of the motor open switch is uniformly turned off without considering the safe operation area. Therefore, there is a problem in the reliability of element protection. Further, in the motor system of Patent Document 5, excessive AC voltage induced in the motor is applied to the inverter by continuing the drive control of the AC motor by the field weakening control during the high rotation state, thereby causing equipment damage. This is not disclosed, and the protection of the semiconductor switching element of the motor opening switch is not disclosed.

  The present invention has been made under the circumstances as described above, and the object of the present invention is to protect a motor open switch configured with a semiconductor switching element in a small size without adding new device parts, and to protect the temperature. It is an object of the present invention to provide a motor control device that can be reliably and reliably performed and an electric power steering device equipped with the motor control device.

  The present invention relates to a motor control device in which a motor is driven and controlled by an inverter based on a current command value calculated by a steering torque from a torque sensor, and a motor release switch composed of an FET is connected between the inverter and the motor. The above-described object of the present invention is to detect a sensor including the torque sensor and the assist state of the inverter, turn on / off the control of the inverter based on the detection result, and detect the presence or absence of abnormality. A motor rotation number detection unit that detects the rotation number of the motor, an energy calculation unit that calculates the energy of the motor back electromotive force voltage and the regenerative current based on the rotation number, and a safety table of the FET. Compared with the operating area, when the energy continues for a predetermined time in the area of the safe operating area, A determination unit that turns off all the FETs of the motor release switch, an abnormality detection unit, and a state detection unit that detects the presence or absence of abnormality based on information from the abnormality detection unit, and the control unit includes the state This is achieved by turning on the control of the inverter when the detection unit detects no abnormality and turning off the control of the inverter when the state detection unit detects the abnormality.

  The object of the present invention is to provide a temperature detection unit that detects the temperature of the FET or the surrounding temperature, and the control unit defines the safe operation region based on the temperature detection value detected by the temperature detection unit. By calculating, a more accurate safe operation area is calculated according to the temperature, or a timer is provided in the determination unit, and the time during which the energy is within the safe operation area is measured by the timer. In addition, since the FET-OFF signal is output when the predetermined time is continued, it is achieved more effectively.

  According to the motor control device of the present invention, when the motor rotation number is high (the motor back electromotive force voltage and the energy of the regenerative current (regenerative power) are in the safe operation range or more), the motor open switch is continuously turned on to generate the regenerative current. Is controlled to return the power to the motor, and a braking force is applied to the rotating motor. This braking force gradually reduces the motor speed, and the safe region (motor back electromotive force voltage and regenerative current energy (regenerative power) is in the safe operating region). Measure the elapsed time after entering the safe operation area, not immediately when entering, and turn off all the semiconductor switching elements (FET) of the motor release switch when the specified time has elapsed continuously I am doing so. For this reason, it is possible to more reliably protect the motor opening switch formed of the semiconductor switching element with an inexpensive configuration without adding new device parts and without adding a new protection circuit.

  In addition, since the temperature of the motor open switch to be protected or its surrounding temperature is taken into account in the calculation of the safe operation area, it is possible to realize ON / OFF control protection that matches the temperature characteristics of the motor open switch. .

  According to the electric power steering apparatus equipped with the motor control apparatus according to the present invention, the semiconductor switching element of the motor opening switch inserted between the motor and the inverter can be reliably and easily protected. Safety and reliability can be further improved.

It is a lineblock diagram showing an outline of an electric power steering device. It is a block diagram which shows the structural example of the control unit (ECU) of an electric power steering apparatus. It is a diagram which shows the structural example of the motor control part of an electric power steering apparatus. It is a characteristic view which shows the characteristic example of the drain-source voltage Vds of FET, and the drain current Id. It is a characteristic view which shows the example of the temperature characteristic of the allowable loss Pd of FET. It is a block diagram which shows the structural example of this invention. It is a characteristic view which shows the example of a characteristic of a data table. It is a timing chart which shows an example of the relay failure by the fluctuation | variation of a motor rotation speed. It is a timing chart which shows the operation example of this invention with respect to the fluctuation | variation of a motor rotation speed. It is a flowchart which shows the operation example of this invention.

  In the present invention, in order to reduce the size of the motor open switch (motor relay), improve the reliability, and reduce the cost, the motor open switch is constituted by a semiconductor switching element (eg, FET). Then, when it becomes impossible to continue assist due to abnormalities (including faults) of sensors such as torque sensors and inverters (including when the ignition key is turned OFF during motor rotation), the motor rotates due to external force. In order to protect the device breakage of the motor open switch by the motor regenerative power (calculated from the back electromotive force and the regenerative current) that is generated from time to time, the motor back electromotive force and regenerative current Calculates the energy of the motor open switch based on the temperature of the motor open switch or the surrounding temperature, and calculates the safe operation range of the motor open switch, and the motor speed is high (the energy of the motor back electromotive force voltage and regenerative current exceeds the safe operation range) In this case, the motor open switch is continuously turned on to perform a control for returning the regenerative current to the power source. Brake force was applied to the rotating motor by the return control of the regenerative current to the power supply, the motor rotation speed gradually decreased, and the motor entered the safe operating range (the motor back electromotive force voltage and the energy of the regenerative current were less than the safe operating range). Thereafter, all semiconductor switching elements of the motor release switch are turned OFF when the predetermined time has elapsed. Thereafter, processing necessary for stopping the assist control is performed.

  While monitoring the temperature information and the motor rotation speed in this way, after the time when the switching loss at the time of FET interruption caused by the regenerative power calculated from the back electromotive voltage and the regenerative current becomes the motor rotation speed falling within the safe operation region, All the semiconductor switching elements of the motor release switch are turned off when the time that stays continuously in the safe operation area exceeds a predetermined time, so the safe operation area due to switching loss when the semiconductor switching element is OFF The semiconductor switching element can be reliably protected without damage or destruction due to deviation, and a highly reliable motor control device and electric power steering device can be provided.

  In general, the safe operation region (AOS: Area Of Safety operation) of the FET in operation is the relationship between the drain current Id and the drain-source voltage Vds as shown in FIG. 4 and the maximum allowable loss Pd as shown in FIG. It depends on the temperature characteristics. However, it varies depending on operating conditions actually used (FET case temperature Tc, operating frequency f, ON width t, etc.). In particular, the maximum allowable loss Pd decreases as the case temperature rises. Therefore, temperature information is important for obtaining an accurate safe operation region. If the temperature by the temperature detection element on the power board can be known, the case of the FET can be obtained. Since the temperature Tc can be estimated, the maximum allowable power Pd corresponding to the temperature can be calculated.

  Therefore, according to the present invention, not only the (regenerative power) determination based on the motor rotation speed but also the temperature of the semiconductor switching element (FET) on the power substrate or the temperature information around the semiconductor switching element (FET) is taken into account in the determination condition, thereby ensuring accurate safety. The operating region is determined, and the semiconductor switching element (FET) can be switched off more safely than the determination based on the rotation speed of the motor alone.

  Note that the motor is free-running when the emergency assist is OFF. Assist OFF factors include an inverter abnormality, ignition key OFF, software / hardware abnormality detection, sensor abnormality, and the like.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 6 shows a configuration example of the present invention corresponding to FIG. 3. In the present invention, the control unit 120 includes an energy calculation unit 121, a determination unit 122, a data table 123, a current control unit 124, a state detection unit 125, A safe operation area calculation unit 126 is provided. The determination unit 122 includes a timer 122A, measures the passage of time described below, and outputs a FET-OFF signal that turns off all the FETU to FETW of the motor release switch 140 when a predetermined time has passed. The data table 123 is preliminarily obtained as a table by calculating the energy W corresponding to the motor rotational speed rpm, that is, the energy W of the motor back electromotive force voltage and the regenerative current with respect to the motor rotational speed rpm, and has a characteristic as shown in FIG. ing. Therefore, the motor back electromotive force voltage and the energy W of the regenerative current can be calculated by detecting the motor rotation speed rpm. In FIG. 7, for example, when the motor rotation speed rpm is ω1, the energy W is calculated as W1.

  The data table 123 may be stored in a nonvolatile memory such as an EEPROM.

  Further, a sensor abnormality detection unit 131 that detects abnormality (including failure) of sensors such as a torque sensor, an inverter abnormality detection unit 135 that detects abnormality (including failure) of the inverter 106, a sensor abnormality detection unit 131, and A state detection unit 125 that detects an abnormality and other states based on the inverter abnormality detection unit 135 and performs necessary processing is provided. The state detection unit 125 receives an assist OFF command and detects all of the assist OFF operations. For example, the state detection unit 125 also detects a state in which the ignition key is turned OFF during motor rotation.

  Further, a motor open switch composed of an FET as a semiconductor switching element is connected to a power supply line (U phase, V phase, W phase) between the inverter 106 and the motor 20 controlled by the current control unit 124 in the control unit 120. 140 (140 U, 140 V, 140 W) is inserted, and the motor opening switch 140 is turned ON / OFF by the motor opening switch control unit 133 controlled by the control unit 120. Further, a thermistor 141 is provided as a temperature sensor of a temperature detecting unit for detecting the temperature of the motor opening switch 140 (140U, 140V, 140W) or its surrounding temperature, and the temperature information Tp detected electrically is Input to the controller 120. The thermistor 141 may be disposed on the power board on which the motor release switch 140 (140U, 140V, 140W) is mounted. The FET1 to FET6 of the inverter 106 and the FET (140U to 140W) of the motor opening switch 140 are mounted on the same substrate.

  The safe operation area calculation unit 126 calculates the safe operation area based on the temperature information Tp from the thermistor 141. The calculated safe operation area is input to the determination unit 122.

  Further, a motor rotation number detection unit 132 that detects the motor rotation number rpm based on the rotation angle θ from the rotation sensor 21 is provided.

  Immediately after the motor back electromotive force voltage and regenerative current energy enter the safe operation region, if the FET of the motor release switch 140 is turned off, the device may be destroyed if the motor rotation speed rpm subsequently increases again. is there. The timing chart of FIG. 8 shows this state, and the inverter is stopped at time t2, and the PWM drive signal is stopped thereafter, so that the motor rotation speed rpm is ramped down as shown in FIG. 8A. Then, when the motor rotation speed rpm reaches the threshold at time t3 and the drive signal of the motor release switch 140 is turned OFF as shown in FIG. 8C, the motor is caused by an external factor as shown in FIG. The rotation speed rpm may fluctuate. In the electric power steering apparatus, it is estimated that the steering wheel is turned by the force received by the tire of the steered wheel depending on the road condition. As an example, the steering wheel tire may come into contact with the road shoulder at the timing. Thus, when the motor rotation speed rpm rises again, the FET may be destroyed.

  Therefore, in the present invention, as shown in FIG. 9, after the inverter is stopped (time point t11), after the time t12 when the motor rotation speed rpm is ramped down and reaches the threshold value, the motor release switch 140 is turned on at a time point t13 after a predetermined time has elapsed. Turn off the drive signal. The drive signal is turned off when the count value of the timer count reaches a threshold value as shown in FIG. As a result, the FET of the motor release switch 140 can be turned off more safely.

  In such a configuration, an example of the operation will be described with reference to the flowchart of FIG.

  When the control operation starts, first, the motor release switch 140 (140U, 140V, 140W) is turned on by the motor release switch control unit 133 via the control unit 120 (step S1), and the current control unit 124 in the control unit 120 turns on. The control of the inverter 106 is turned on and the assist control starts (step S2). The state detection unit 125 determines whether or not an abnormality (including a failure) is detected in the sensor abnormality detection unit 131 or the inverter abnormality detection unit 135 (step S3). If no abnormality is detected, the state detection unit 125 assists. Control continues.

If an abnormality is detected in step S3, it is determined that the assist control cannot be continued, and the control of the inverter 106 is turned off by the control unit 120 (step S10). When the control of the inverter 106 is turned off, the motor rotation number detection unit 132 detects the motor rotation number rpm of the motor 20 rotated by an external force (step S11), and the energy calculation unit 121 in the control unit 120 rotates the motor. Based on several rpm, the motor back electromotive force E and the energy W of the regenerative current are calculated using the data table 123 (step S12). The motor back electromotive force E is obtained according to the following formula 1, and is actually measured and tabulated together with the measurement of the regenerative current.
(Equation 1)
E = k. Motor rotation speed per unit time. However, k is a motor constant determined by the magnetic flux density of the motor 20, the rotor diameter, and the like.

The thermistor 141 detects the temperature (or ambient temperature) Tp of the motor opening switch 140 (step S13), and further calculates the maximum allowable loss Pd (step S14) and inputs it to the control unit 120. The safe operation area calculation unit 126 in the control unit 120 calculates the safe operation area of the motor opening switch 140 based on the temperature Tp and the maximum allowable loss Pd (step S15).

  The calculated safe operation region is input to the determination unit 122, and the determination unit 122 determines whether or not the calculated energy W deviates from the safe operation region of the FET constituting the motor release switch 140 (step S20). . That is, it is determined whether or not “energy calculation result> safe operation range”, and when the calculated energy W deviates from the calculated safe operation range, that is, when the motor rotation speed rpm is high, regeneration is performed. The electric power is a danger region causing FET breakdown, and the switching loss due to the regenerative current is more than the safe operation region. The OFF timer is reset and the ON operation of the motor release switch 140 is continued. Thus, control for returning the regenerative current to the power source is performed, and a braking force is applied to the rotating motor.

  Then, the motor rotation speed rpm gradually decreases due to the braking force, and after the switching loss due to the regenerative current enters the safe operation region, the OFF timer is turned off after the safety cutoff region of the motor release switch 140, that is, the energy W. The count is incremented (step S21), and it is determined whether or not the count value of the OFF timer is equal to or greater than the switch OFF determination threshold value (step S22). When the count value of the OFF timer becomes equal to or greater than the switch OFF determination threshold, the motor release switch 140 is turned OFF and the OFF timer is reset (step S23). When the count value of the OFF timer is less than the switch OFF determination threshold value, the process returns to step S11 and the above operation is repeated.

  As a result, the FET constituting the motor release switch 140 is not destroyed, and processing necessary for stopping the assist control is executed after the motor release switch 140 is turned OFF.

  Note that the numerical values such as withstand voltage data and safe operation area determined by the determination unit 122 are compared with the withstand voltage data and safe operation area, etc. Since it fluctuates greatly due to wiring resistance, etc., it is derived by measurement with an actual machine.

  In the above-described embodiment, the motor rotation speed is detected based on the rotation sensor (resolver). However, the motor rotation speed can also be estimated by detecting the current using the motor terminal voltage and the shunt resistance.

  In the above-described embodiment, the thermistor is taken as an example of the temperature sensor. However, a temperature measuring resistor, a thermocouple, an IC temperature sensor using the temperature characteristics of the transistor, a crystal thermometer using the Y-cut of the crystal, It is also possible to use.

1 Handle 2 Column shaft (steering shaft, handle shaft)
10 Torque sensor 12 Vehicle speed sensor 20 Motor 100 Control unit (ECU)
101 current command value calculation unit 104 PI control unit 105 PWM control unit 106 inverter 110 compensation signal generation unit 120 control unit 121 energy calculation unit 122 determination unit 122A timer 123 data table 125 state detection unit 126 safe operation region calculation unit 131 sensor abnormality detection Part 132 motor rotation number detection part 133 motor opening switch control part 140 motor opening switch 141 thermistor

Claims (4)

In a motor control device in which a motor is driven and controlled by an inverter based on a current command value calculated by a steering torque from a torque sensor, and a motor release switch composed of an FET is connected between the inverter and the motor.
A control unit that detects the assist state of the sensors including the torque sensor and the inverter, and turns on / off the control of the inverter based on a detection result;
A motor rotation number detection unit for detecting the rotation number of the motor;
Based on the number of revolutions, an energy calculation unit that calculates the energy of the motor back electromotive force voltage and the regenerative current from a data table;
The energy is compared with the safe operation area of the FET, and when the energy continues in the safe operation area for a predetermined time, a determination unit that turns off all the FETs of the motor open switch,
A state detection unit that detects the presence or absence of an abnormality based on information from the abnormality detection unit and the abnormality detection unit;
Comprising
The control unit turns on the control of the inverter when the state detection unit does not detect abnormality, and turns off the control of the inverter when the state detection unit detects abnormality. Control device. A temperature detection unit that detects the temperature of the FET or the surrounding temperature is provided, and the control unit calculates the safe operation region based on the temperature detection value detected by the temperature detection unit, thereby the temperature The motor control device according to claim 1, wherein a more accurate safe operation area is calculated according to the operation. A timer is provided in the determination unit, and a time during which the energy is within the safe operation region is measured by the timer, and an FET-OFF signal is output when the predetermined time has continued. The motor control apparatus according to 1 or 2. An electric power steering apparatus comprising the motor control apparatus according to claim 1.

Images