Electronic control device

Abstract

An electronic control device according to the present disclosure drives and controls a motor, wherein: an inverter supplies electric power to the motor; an electric power supply relay connects and disconnects an electric power supply and the inverter; a motor relay connects and disconnects the inverter and the motor; and a drive system detects a motor terminal voltage of the motor, and, when the motor terminal voltage exceeds a predetermined voltage reference value, disconnects the inverter from the electric power supply relay, connects the inverter to a potential reference point, and connects the inverter and the motor to the motor relay.

Description

Electronic control unit

[0001] The present disclosure relates to an electronic control device, for example, an electronic control device for a vehicle.

[0002] Some electronic control devices that control motors include an inverter, a power supply relay, and a fail-safe circuit. The power supply relay turns on and off the power supply from the power supply to the inverter. The fail-safe circuit includes a motor relay for each phase of the motor. The motor relay turns on and off the power supply from the inverter to the motor. For example, a motor actuator for vehicle-mounted equipment described in Patent Document 1 turns off the inverter's switching elements when an abnormality is detected, and turns off the power supply relay and motor relay simultaneously when the rotational speed of the motor rotor falls below a predetermined rotational speed. Since the back electromotive force generated by the rotation of the motor does not exceed the withstand voltage of the circuit elements that make up the inverter, motor relay, power supply relay, etc., secondary failures are prevented.

[0003] Patent No. 7202204

[0004] However, the motor actuator for vehicle-mounted equipment described in Patent Document 1 may be unable to monitor the location of the abnormality or failure, or the condition of the abnormality or failure, and may be unable to monitor the situation in which the motor rotation speed drops below a predetermined rotation speed after the inverter switching element is turned off. Furthermore, it may be unable to turn off the power relay and motor relay with a delay after a certain period of time has elapsed. For example, an abnormality may occur in the components that make up the motor actuator, such as an off failure in the power relay drive circuit, an off failure in the motor relay drive circuit, an abnormality in the motor rotation sensor, or an abnormality in the CPU. In such cases, it is impossible to achieve delayed control to turn off the power relay and motor relay. When a motor rotates at high speed, back electromotive force generates a voltage exceeding the withstand voltage toward the power supply, creating a risk of circuit element failure.

[0005] A first aspect of the present disclosure is an electronic control device that drives and controls a motor, comprising: an inverter that supplies power to the motor; a power supply relay that connects and disconnects a power supply to the inverter; a motor relay that connects and disconnects the inverter to the motor; and a drive system that detects a motor terminal voltage of the motor, and when the motor terminal voltage exceeds a predetermined voltage reference value, disconnects the inverter from the power supply relay and connects it to a potential reference point, and connects the inverter to the motor via the motor relay.

[0006] According to the present disclosure, the risk of circuit elements failing due to the back electromotive force of the motor can be reduced or prevented.

[0007] Fig. 1 is a diagram showing a configuration example of an electronic control device according to embodiment 1. Fig. 2 is a diagram showing a configuration example of a motor relay / inverter drive circuit according to embodiment 1. Fig. 3 is a flowchart showing an operation example of the electronic control device according to embodiment 1. Fig. 4 is a diagram showing a configuration example of an electronic control device according to embodiment 2.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Common or corresponding elements in the various drawings are designated by the same reference numerals, and the description thereof will be incorporated unless otherwise specified. <Embodiment 1> First, embodiment 1 of the present disclosure will be described. FIG. 1 is a diagram illustrating an example configuration of an electronic control device according to this embodiment. In the example of FIG. 1, the electronic control device is configured as a control unit CU1 for a vehicle. The control unit CU1 is applied to steering assistance using an electric power steering device PS1. In this application, steering assistance control is also referred to as assist control. The control unit CU1 includes a power supply circuit 1, an IG I / F circuit 2, a torque sensor I / F circuit 3, a CAN communication circuit 4, a CPU 5, a motor relay drive circuit 10, a power supply relay drive circuit 11, a drive circuit 12, a power supply relay 13, an inverter 14, a motor relay 15, a motor angle sensor 16, and a motor 17. The motor relay drive circuit 10 , the power relay drive circuit 11 , and the inverter drive circuit 12 I of the drive circuit 12 constitute a drive system that controls the power relay 13 , the inverter 14 , and the motor relay 15 to drive the motor 17 .

[0009] The control unit CU1 is connected to a power supply 20, an ignition mechanism IG21, a torque sensor 22, and a CANBUS 23 using connectors. The connectors are installed, for example, on the housing or board of the control unit CU1. The power supply 20 supplies power to the control unit CU1. The power supply 20 is, for example, a storage battery capable of supplying DC power. The positive electrode of the power supply 20 is connected to one end of a power supply circuit 1 of the control unit CU1. The negative electrode of the power supply 20 is connected to a potential reference point. The potential reference point is a reference point that provides a reference potential. The control unit CU1 operates by consuming power supplied from the power supply 20. The power supply circuit 1 distributes the power supplied from the power supply 20 to each device in the control unit CU1.

[0010] The ignition mechanism IG21 is a switching mechanism that controls the activation (ON) or deactivation (OFF) of the vehicle's operating mechanisms. The vehicle's operating mechanisms include the electric power steering device PS1. The ignition mechanism IG21 outputs an ignition signal indicating activation or deactivation to the control unit CU1. The IG I / F (Ignition Interface) circuit 2 waits for an ignition signal input from the ignition mechanism IG21. When an ignition signal indicating activation is input while the control unit CU1 is not operating, the IG I / F circuit 2 activates the control unit CU1. The IG I / F circuit 2 activates the power supply circuit 1 to start supplying power to each device of the control unit CU1. The CPU 5 then starts the activation process. When an ignition signal indicating deactivation is input while the control unit CU1 is operating, the IG I / F circuit 2 deactivates the control unit CU1. The IG I / F circuit 2 starts a shutdown process (shutdown) in the CPU 5. After the shutdown process is completed, the IG I / F circuit 2 stops the power supply circuit 1 to stop the power supply to each device in the control unit CU1.

[0011] The torque sensor 22 detects steering torque generated by the rotation of the steering wheel (not shown) and notifies the control unit CU1 of the detected steering torque. The torque sensor I / F (Interface) circuit 3 notifies the CPU 5 of the steering torque notified by the torque sensor 22. The CANBUS (Controller Area Network BUS) 23 is a communication path that connects multiple devices via a wired connection in accordance with the CAN standard so that various data can be communicated. The CAN standard is an example of a communication method defined by ISO 11898. The CANBUS 23 is capable of communication with other devices installed in the vehicle. The other devices may include various instruments that acquire vehicle information indicating the vehicle's driving status. Examples of the other devices include a speedometer, a lateral acceleration sensor, or a yaw rate sensor. The CAN communication circuit 4 connects the CPU 5 to the other devices via the CANBUS 23. The CAN communication circuit 4 relays communication between the CPU 5 and the other devices. The CAN communication circuit 4 can acquire vehicle information indicating the driving status of the vehicle from instruments inside the vehicle.

[0012] The motor 17 is, for example, a three-phase brushless motor. The motor 17 has motor windings 17M. In the example of FIG. 1 , the motor windings 17M are three-phase windings. That is, the motor windings 17M include a U-phase winding, a V-phase winding, and a W-phase winding. The motor windings 17M are configured as a winding set by connecting the U-phase winding, the V-phase winding, and the W-phase winding. The motor windings may be connected in any of a star connection, a Y connection, or the like. In a star connection, the other ends of the U-phase winding, the V-phase winding, and the W-phase winding are all connected to a single node. In a Y connection, the other ends of two of the U-phase winding, the V-phase winding, and the W-phase winding are each connected to a single node. Therefore, a three-phase winding configured in a Y connection has three nodes. In either of the connection structures, AC power of the corresponding phase is supplied to one end of each phase winding, and one of the nodes or one of the ends of the winding is connected to a potential reference point.

[0013] The motor 17 includes a rotor. The rotor has a permanent magnet located at a position where the induced magnetic field generated by the motor windings 17M reaches. If the motor 17 is a three-phase brushless motor, the motor windings 17M form a stator. The motor windings 17M generate an AC magnetic field using three-phase AC power supplied from the inverter 14, causing the rotor to rotate. In FIG. 1, U, V, and W represent the U-phase, V-phase, and W-phase of the motor windings 17M, respectively.

[0014] In the example of FIG. 1 , the rotor of the motor 17 engages with the steering mechanism of the electric power steering device PS1. The torque generated by the rotation of the rotor serves as an assist torque that assists the driver in steering. The steering mechanism controls the direction of the wheels of the vehicle using the assist torque. In this application, the rotation speed of the rotor of the motor 17 may be referred to as the rotation speed of the motor 17 or simply as the rotation speed. Note that this disclosure mainly focuses on the case where the motor 17 is a three-phase brushless motor, but is not limited to this. The motor 17 may also be a polyphase motor having polyphase windings of four or more phases.

[0015] The motor relay drive circuit 10 controls the state of the motor relay 15 to an on / off state corresponding to the operating mode information notified by the CPU 5. The motor relay drive circuit 10 generates a motor relay control signal indicating the on / off state and outputs the generated motor relay control signal to the motor relay 15. For example, when the CPU 5 instructs the motor relay drive circuit 10 to operate in a normal mode, the motor relay drive circuit 10 sets the state of the motor relay 15 to an on state. The motor relay drive circuit 10 outputs a motor relay control signal indicating an on command to the motor relay 15. When the CPU 5 notifies the motor relay drive circuit 10 of an abnormal mode, the motor relay drive circuit 10 sets the state of the motor relay 15 to an off state. The motor relay drive circuit 10 outputs a motor relay control signal indicating an off command to the motor relay 15.

[0016] The motor relay 15 connects and disconnects the inverter 14 and the motor winding 17M in accordance with a motor relay control signal input from the motor relay drive circuit 10. For example, when the motor relay control signal indicating an ON command is input from the motor relay drive circuit 10, the motor relay 15 connects the inverter 14 and the motor winding 17M and supplies the power supplied from the inverter 14 to the motor winding 17M. When the motor relay control signal indicating an OFF state is input from the motor relay drive circuit 10, the motor relay 15 cuts off the connection between the inverter 14 and the motor winding 17M and cuts off the power supply from the inverter 14.

[0017] The motor relay 15 includes a switching element for each phase. Each switching element electrically opens and closes a connection between one end and the other end in accordance with the voltage of an electrical signal applied to the base end. The switching element is, for example, a metal-oxide-semiconductor field-effect transistor (MOSFET). A MOSFET generally includes a source, a drain, and a gate. The source, drain, and gate correspond to one end, the other end, and the base end, respectively. The motor relay control signal indicating an ON command is indicated by a high voltage value significantly higher than the reference potential. The motor relay control signal indicating an OFF command is indicated by a low voltage value significantly lower than the high voltage value.

[0018] The power relay drive circuit 11 controls the state of the power relay 13 to an on / off state corresponding to the operating mode information notified by the CPU 5. The power relay drive circuit 11 generates a power relay control signal indicating the corresponding on / off state and outputs the generated power relay control signal to the power relay 13. For example, when the CPU 5 instructs normal mode, the power relay drive circuit 11 sets the state of the power relay 13 to the on state. The power relay drive circuit 11 outputs a power relay control signal indicating an on command to the power relay 13. When the CPU 5 notifies the power relay 13 of abnormal mode, the power relay drive circuit 11 sets the state of the power relay 13 to the off state. The power relay drive circuit 11 outputs a power relay control signal indicating an off command to the power relay 13.

[0019] The power relay 13 connects and disconnects the power supply 20 and the inverter 14 in accordance with a power supply relay control signal input from the power supply relay drive circuit 11. For example, when a power supply relay control signal indicating an ON command is input from the power supply relay drive circuit 11, the power relay 13 connects the power supply 20 and the inverter 14 and supplies power supplied from the power supply 20 to the inverter 14. When a power supply relay control signal indicating an OFF command is input from the power supply relay drive circuit 11, the power relay 13 cuts off the connection between the power supply 20 and the inverter 14 and cuts off the power supply from the power supply 20. The power supply relay 13 includes two switching elements connected in series. The number of switching elements included in the power supply relay 13 may be one or three or more. However, by connecting multiple switching elements in series in the power supply relay 13, the voltage applied to the entire power supply relay 13 is distributed among the multiple switching elements based on their respective electrical resistances, ensuring a sufficient voltage resistance.

[0020] Next, an example configuration of the inverter 14 will be described. The inverter 14 includes an upper-stage switching element group 14U, a lower-stage switching element group 14D, and a resistor element group 14R. The upper-stage switching element group 14U is also referred to as the "upper arm," and the lower-stage switching element group 14D is also referred to as the "lower arm." The upper-stage switching element group 14U includes one switching element for each phase, for a total of three switching elements. Hereinafter, the individual switching elements belonging to the upper-stage switching element group 14U may be referred to as "upper-stage switching elements." The lower-stage switching element group 14D includes one switching element for each phase, for a total of three switching elements. Hereinafter, the individual switching elements belonging to the lower-stage switching element group 14D may be referred to as "lower-stage switching elements." The resistor element group 14R includes one resistor element for each phase, for a total of three resistor elements.

[0021] One end of the upper-stage switching element is connected to the other end of the power supply relay 13 that is common to all phases. The other end of the upper-stage switching element is connected to one end of the lower-stage switching element corresponding to each phase and one end of the motor relay 15. One end of the lower-stage switching element is connected to the other end of the upper-stage switching element corresponding to each phase and one end of the motor relay 15. The other end of the lower-stage switching element is connected to one end of the resistor element corresponding to each phase. One end of the resistor element is connected to the other end of the lower-stage switching element corresponding to each phase. The other ends of the resistor elements are all connected to the potential reference point.

[0022] From another perspective, the inverter 14 has a group of circuit elements, each of which has an upper-stage switching element, a lower-stage switching element, and a resistor element connected in series for each phase. This group of circuit elements is also called a "leg." For each phase, a node between the other end of the upper-stage switching element and one end of the lower-stage switching element is connected to one end of the motor winding 17M via the motor relay 15. The upper-stage switching element and the lower-stage switching element connect and disconnect one end to the other end in accordance with a switching signal input to their respective base ends from the drive circuit 12. When the upper-stage switching element for a given phase closes both ends in response to an ON command and the corresponding lower-stage switching element opens both ends in response to an OFF command, power supplied from the power supply relay 13 is supplied to the motor winding 17M via the motor relay 15. When the upper-stage switching element opens both ends in response to an OFF command and the corresponding lower-stage switching element closes both ends in response to an ON command, the potential at the other end of the upper-stage switching element approaches the reference potential. Therefore, the inverter 14 supplies an AC current whose voltage fluctuates periodically to the motor winding 17M via the motor relay 15 based on a switching signal that periodically repeats on and off commands with different phases for each phase.

[0023] Next, a configuration example of the drive circuit 12 will be described. The drive circuit 12 includes an inverter drive circuit 12I, a motor current detection circuit 12M, and an abnormality detection unit 12A. The inverter drive circuit 12I of the drive circuit 12 supplies three-phase AC power to the motor windings 17M in accordance with a current control amount notified to the inverter 14 by the CPU 5. The inverter drive circuit 12I calculates a voltage command value on a three-phase coordinate system for each phase based on the rotation speed and rotation angle of the motor 17 notified by the CPU 5. For each set of stages and phases of the inverter 14, the inverter drive circuit 12I generates a PWM (Pulse Width Modulation) signal as a switching signal based on the voltage command value of the corresponding phase. The PWM signal is a binary signal that alternates between a first value and a second value at predetermined carrier wave periods.

[0024] More specifically, the inverter drive circuit 12I generates a carrier wave whose waveform repeats at predetermined carrier wave periods. The carrier wave is, for example, a triangular wave. The inverter drive circuit 12I normalizes the voltage command value for each phase so that the range of the voltage command value is equal to the range of the signal value representing the carrier wave. The inverter drive circuit 12I generates a switching signal representing an ON command or an OFF command for each phase based on the normalized voltage command value and the signal value of the carrier wave. During a period in which the voltage command value for each phase is greater than the signal value of the carrier wave, the inverter drive circuit 12I sets the value of the upper switching signal to a value representing an ON command (e.g., 1) and the value of the lower switching signal to a value representing an OFF command (e.g., 0). The inverter drive circuit 12I generates a switching signal representing the set value for each set of stages and phases and outputs the generated switching signal to the inverter 14.

[0025] The inverter drive circuit 12I may receive operation mode information indicating a regenerative braking mode from the CPU 5. In this case, the inverter drive circuit 12I generates, for example, switching signals indicating an OFF state for each upper-stage phase and switching signals indicating an ON state for each lower-stage phase. Alternatively, the inverter drive circuit 12I may generate switching signals indicating an ON state for each upper-stage phase and switching signals indicating an OFF state for each lower-stage phase. The inverter drive circuit 12I outputs the generated switching signals to the inverter 14. The inverter drive circuit 12I may receive operation mode information indicating an abnormality mode from the CPU 5. In this case, the inverter drive circuit 12I sets the state of the switching elements of the inverter 14 to the OFF state for all phase-stage sets. Therefore, the inverter drive circuit 12I outputs switching signals indicating an OFF command to the inverter 14 for all phase-stage sets.

[0026] The motor current detection circuit 12M detects the current supplied from the inverter 14 to the motor winding 17M via the motor relay 15 as the motor current for each phase. The motor current detection circuit 12M detects the voltage generated across the resistor element provided in the inverter 14. The detected voltage corresponds to the motor terminal voltage generated in the motor winding 17M. The voltage is also proportional to the current value of the current flowing through the resistor element. Therefore, if the resistance value of the resistor element and the resistance value of the motor winding 17M are known, the detected voltage can be considered as the motor current. The motor current detection circuit 12M outputs the motor current detected for each phase to the CPU 5.

[0027] The abnormality detection unit 12A monitors the operating status of the inverter 14 and detects any abnormalities in operation. For example, the abnormality detection unit 12A detects the motor current for each phase, similar to the motor current detection circuit 12M, and determines whether an abnormality has occurred based on whether the detected motor current is within a predetermined reference range. Here, whether an excessively high or low current has occurred for each phase is detected. The abnormality detection unit 12A may also calculate the sum of the motor currents for all phases and determine whether an abnormality has occurred based on whether the calculated sum is within a predetermined tolerance range. Ideally, the sum of the motor currents is always zero, so it is possible to detect whether the motor currents are balanced among multiple phases. When an abnormality is detected, the abnormality detection unit 12A notifies the CPU 5 of abnormality detection information indicating the detection of an abnormality.

[0028] The CPU 5 constitutes the computer system of the control unit CU1. The CPU 5 executes various processes for realizing and controlling the functions of the control unit CU1 according to commands written in pre-installed programs. The CPU 5 controls steering assistance (assist control) and the operation mode. For example, when no abnormality detection information is input from the drive circuit 12, the CPU 5 determines the operation mode as the normal mode. In the normal mode, the CPU 5 executes assist control.

[0029] When performing assist control, the CPU 5 calculates a control amount for supplying power to the motor winding 17M based on the steering torque and vehicle information. The CPU 5 calculates a target torque based on the steering torque and vehicle information according to a known steering assist control method. The CPU 5 receives the steering torque from the torque sensor 22 via the torque sensor I / F circuit 3. The CPU 5 calculates a control amount of current for the motor winding 17M using a known calculation method so as to reduce the difference between the target torque and the steering torque. The CPU 5 may use any method, such as MTPA (Maximum Torque Per Ampere) control or MTPV (Maximum Torque Per Flux) control. The CPU 5 outputs the calculated control amount to the drive circuit 12.

[0030] When abnormality detection information is input from the drive circuit 12, the CPU 5 determines the operating mode as abnormal mode. The CPU 5 may also obtain the abnormality detection information for the inverter 14 from another device. In that case, the drive circuit 12 may omit the abnormality detection unit 12A. As another device, for example, the control unit CU1 may include a dedicated abnormality detection circuit. The CPU 5 stops assist control in abnormal mode. The CPU 5 notifies the motor relay drive circuit 10, the power supply relay drive circuit 11, and the drive circuit 12 of operating mode information indicating the abnormal mode. This causes the power supply relay drive circuit 11 to control the switching state of the power supply relay 13 to the off state, and the motor relay drive circuit 10 to control the switching state of the motor relay 15 to the off state. The drive circuit 12 also controls the switching states of all switching elements of the inverter 14 in that system to the off state.

[0031] The CPU 5 receives information about the rotation angle of the rotor of the motor 17 from the motor angle sensor 16. The CPU 5 calculates the number of rotations per unit time and the direction of rotation of the motor 17 based on the input rotation angle information. The number of rotations per unit time corresponds to the rotation speed. The CPU 5 calculates the number of rotations by subtracting the next most recent rotation angle from the most recent input rotation angle and dividing the resulting difference by the sampling period of the rotation angle. The CPU 5 can determine the direction of rotation based on whether the calculated rotation speed is a positive value. The CPU 5 uses information about the rotation speed and direction of rotation of the motor 17 for assist control. The CPU 5 may obtain information about the rotation speed and direction of rotation of the motor 17 from another device. In this case, the CPU 5 can omit the process of calculating the motor rotation speed and direction of rotation. For example, the control unit CU1 may include a rotation speed sensor instead of the motor angle sensor 16 as another device.

[0032] The CPU 5 is notified of information about the current in each part of the inverter 14 from the drive circuit 12. For example, the CPU 5 is notified of the current value for each phase supplied from the inverter 14 to the motor winding 17M. The CPU 5 uses the notified current value for assist control. The CPU 5 can detect an abnormality in the inverter 14 by receiving abnormality detection information from the drive circuit 12. In this case, the CPU 5 determines that the operating mode is an abnormal mode, and outputs operating mode information indicating the abnormal mode to the motor relay drive circuit 10, power supply relay drive circuit 11, and drive circuit 12 related to that system.

[0033] The motor relay / inverter drive circuit 18 is connected to the motor terminals for each phase and operates using the motor terminals as a power supply source. The motor terminal corresponds to one end of the motor winding 17M or the terminal connected thereto. That is, the motor relay / inverter drive circuit 18 operates by consuming power supplied from the motor terminals. The motor relay / inverter drive circuit 18 is mainly composed of passive elements, which reduces power consumption. The motor relay / inverter drive circuit 18 detects the motor terminal voltage and determines for each phase whether the detected motor terminal voltage exceeds a predetermined voltage reference value. The motor terminal voltage corresponds to the voltage generated at the motor terminals.

[0034] When the detected motor terminal voltage exceeds a predetermined voltage reference value, the motor relay / inverter drive circuit 18 connects the inverter 14 and the motor 17 to the motor relay. In this case, the motor relay / inverter drive circuit 18 connects the inverter 14 to the potential reference point. A regenerative current path is formed by the motor relay 15 and the lower-stage switching elements of the inverter 14, so that a back electromotive force is generated by electromagnetic induction due to the rotation of the motor 17, and an electromagnetic brake is activated. Because the rotation speed of the motor 17 decreases, the risk of failure of circuit elements caused by the application of a voltage exceeding the withstand voltage due to the back electromotive force generated by the high-speed rotation of the motor 17 can be reduced or avoided.

[0035] Next, an example configuration of the motor relay / inverter drive circuit 18 will be described. FIG. 2 is a diagram showing an example configuration of the motor relay / inverter drive circuit 18. The motor relay / inverter drive circuit 18 includes a power supply circuit 30, a motor terminal voltage determination circuit 31, a drive signal hold circuit 32, an upper inverter off drive circuit 33, a lower inverter on drive circuit 34, a motor relay on drive circuit 35, and a rectifier element 38. The power supply circuit 30 has a storage element (not shown) and is connected to the motor terminals for each phase across the rectifier element 38. The rectifier element 38 passes current flowing from the motor terminals to the power supply circuit 30, preventing backflow from the power supply circuit 30 to the motor terminals. The power supply circuit 30 holds the rectified power supplied from the motor terminals and outputs a constant voltage for a predetermined period of time or longer. That is, even if the motor terminal voltage drops below a predetermined lower voltage limit or if power supply from the power supply 20 is stopped, the power supply circuit 30 maintains a constant motor terminal voltage at its maximum value and supplies power at that voltage for a certain period of time or more to other circuits in the motor relay / inverter drive circuit 18. From another perspective, the power supply circuit has the function of stabilizing the AC motor terminal voltage that fluctuates over time and supplying DC power with a constant voltage. Here, the storage element of the power supply circuit 30 stores the power that flows in via the rectifier element 38 and supplies the stored power to other circuits in the motor relay / inverter drive circuit 18. The storage element is, for example, a capacitor.

[0036] The motor terminal voltage determination circuit 31 operates using power supplied from the power supply circuit 30. The motor terminal voltage determination circuit 31 determines whether the motor terminal voltage in at least one phase exceeds a predetermined voltage reference value. The voltage reference value may be set to a back electromotive force that generates a back electromotive force in the motor 17, causing the voltage applied to each circuit element to be lower than the withstand voltage of the element. This circuit element corresponds to, for example, the power supply relay 13, the inverter 14, the motor relay 15, or other components that form the power supply path from the power supply 20 to the motor 17. The reference value may be a single fixed value or a value with hysteresis. For example, the voltage reference value used to determine whether the motor terminal voltage exceeds the voltage reference value when the motor terminal voltage is rising may be smaller than the voltage reference value used to determine whether the motor terminal voltage is below the voltage reference value when the motor terminal voltage is falling. The motor terminal voltage determination circuit 31 outputs a determination result signal indicating whether the motor terminal voltage exceeds the voltage reference value to the inverter upper stage off drive circuit 33, the inverter lower stage on drive circuit 34, and the motor relay on drive circuit 35 via the drive signal holding circuit 32.

[0037] When the determination result signal input from the motor terminal voltage determination circuit 31 indicates that the motor terminal voltage exceeds the voltage reference value, the drive signal hold circuit 32 holds the output as a drive signal for a predetermined period of time or more. After the determination result signal input from the motor terminal voltage determination circuit 31 changes to a state indicating that the motor terminal voltage is equal to or lower than the voltage reference value, the drive signal hold circuit 32 continues to output the signal before the change for a predetermined period of time or more.

[0038] The inverter upper-stage off drive circuit 33 operates using power supplied from the power supply circuit 30. When the determination result signal input from the drive signal hold circuit 32 indicates that the motor terminal voltage exceeds the voltage reference value, the inverter upper-stage off drive circuit 33 generates a switching signal indicating an off command for the upper-stage switching elements of the inverter 14 and outputs the generated switching signal to the inverter 14. The upper-stage switching elements of the inverter 14 may receive switching signals from both the inverter upper-stage off drive circuit 33 and the drive circuit 12. In this case, the upper-stage switching elements of each phase of the inverter 14 prioritize the switching signal input from the inverter upper-stage off drive circuit 33. That is, the upper-stage switching elements of each phase of the inverter 14 open their both ends in accordance with the switching signal input from the inverter upper-stage off drive circuit 33 and reject the switching signal input from the drive circuit 12. When the determination result signal input from the drive signal hold circuit 32 indicates that the motor terminal voltage is equal to or lower than the voltage reference value, the inverter upper-stage off drive circuit 33 stops outputting the switching signal.

[0039] The inverter lower-stage ON drive circuit 34 operates using power supplied from the power supply circuit 30. When the determination result signal input from the drive signal hold circuit 32 indicates that the motor terminal voltage exceeds the voltage reference value, the inverter lower-stage ON drive circuit 34 generates a switching signal indicating an ON command for the lower-stage switching elements of the inverter 14 and outputs the generated switching signal to the inverter 14. The lower-stage switching elements of the inverter 14 may receive switching signals from both the inverter lower-stage ON drive circuit 34 and the drive circuit 12. In this case, the lower-stage switching elements of each phase of the inverter 14 prioritize the switching signal input from the inverter lower-stage ON drive circuit 34. That is, the lower-stage switching elements of each phase of the inverter 14 close both ends in accordance with the switching signal input from the inverter lower-stage ON drive circuit 34 and reject the switching signal input from the drive circuit 12. When the determination result signal input from the drive signal hold circuit 32 indicates that the motor terminal voltage is equal to or lower than the voltage reference value, the inverter lower-stage ON drive circuit 34 stops outputting the switching signal.

[0040] The motor relay-on drive circuit 35 operates using power supplied from the power supply circuit 30. When the determination result signal input from the drive signal hold circuit 32 indicates that the motor terminal voltage exceeds the voltage reference value, the motor relay-on drive circuit 35 generates a switching signal indicating an on command for the switching element of the motor relay 15 and outputs the generated switching signal to the motor relay 15. The switching elements of the motor relay 15 may receive switching signals from both the motor relay-on drive circuit 35 and the motor relay drive circuit 10. In this case, the switching elements of each phase of the motor relay 15 prioritize the switching signal input from the motor relay-on drive circuit 35. That is, the switching elements of each phase of the motor relay 15 close both ends in accordance with the switching signal input from the motor relay-on drive circuit 35 and reject the switching signal input from the motor relay drive circuit 10. When the determination result signal input from the drive signal hold circuit 32 indicates that the motor terminal voltage is equal to or lower than the voltage reference value, the motor relay-on drive circuit 35 stops outputting the switching signal.

[0041] As described above, when two types of switching signals are input to the inverter upper-stage off drive circuit 33, the inverter lower-stage on drive circuit 34, and the motor relay on drive circuit 35, different instructions are transmitted to each of them. Such an event occurs, for example, when an external force is applied, causing the motor 17 to rotate at high speed and the motor terminal voltage to exceed the voltage reference value. An external force may be generated by an event such as a tire running over a curb while the vehicle is in operation. In such a case, the command from the motor relay / inverter drive circuit 18 is given priority, and a regenerative current path for the motor 17 is formed, thereby reducing or preventing the risk of circuit element failure.

[0042] When a regenerative current path for the motor 17 is formed, the motor terminal voltage drops. In this case, the motor terminal voltage changes from a state higher than the reference voltage to a state lower than the reference voltage, causing the determination result signal output from the motor terminal voltage determination circuit 31 to fluctuate. In this state, if the motor relay 15 and the lower-stage switching elements of the inverter 14 are immediately released from their on states, the motor terminal voltage rises due to the back electromotive force generated by the rotation of the motor 17. Because the motor terminal voltage changes from a state lower than the reference voltage to a state higher than the reference voltage, the determination result signal output from the motor terminal voltage determination circuit 31 fluctuates again. As a result, the state of the motor relay 15 transitions from the off state to the on state, and the state of the lower-stage switching elements of the inverter 14 transitions from the off state to the on state. Both the motor relay 15 and the inverter 14 switch between the on and off states in a short period of time, which can cause hunting. Therefore, the drive signal hold circuit 32 holds the value of the determination result signal for a certain period of time, thereby avoiding hunting. Therefore, the regenerative current path is maintained until the rotation speed of the motor 17 and the regenerative current are sufficiently reduced.

[0043] Even when the control unit CU1 is not operating, an external force may cause the motor 17 to rotate at high speed, causing the motor terminal voltage to exceed the reference voltage value. This can occur, for example, when a vehicle is jacked up while not in operation. Even in this case, the motor relay / inverter drive circuit 18 can operate by using the motor terminals as a power source and consuming the power supplied from the motor terminals. This operation forms a regenerative current path for the motor 17, reducing or preventing the risk of circuit element failure.

[0044] The motor terminal voltage determination circuit 31 may include an output interface capable of outputting a determination status output indicating whether the motor terminal voltage exceeds the voltage reference value. The motor terminal voltage determination circuit 31 outputs the determination status output to the CPU 5, for example. The CPU 5 can monitor whether the motor terminal voltage exceeds the voltage reference value using the determination status output input from the motor terminal voltage determination circuit 31. The motor terminal voltage determination circuit 31 may also include an input interface capable of inputting a function on / off command indicating whether a function is on or off. The motor terminal voltage determination circuit 31 starts or stops its own function in accordance with the function on / off command input from the CPU 5, for example. This function on / off refers to the switching control by the inverter upper-stage off drive circuit 33, the inverter lower-stage on drive circuit 34, and the motor relay on drive circuit 35. In other words, the function to be on / off is regenerative braking by forming a regenerative current path for the motor 17. When the function is instructed to be turned off, the motor terminal voltage determination circuit 31 monitors the motor terminal voltage, and if the motor terminal voltage exceeds the voltage reference value, it rejects the determination result signal indicating whether the motor terminal voltage exceeds the voltage reference value and does not output it to the downstream drive signal hold circuit 32. In this case, even if the motor terminal voltage exceeds the voltage reference value, the motor terminal voltage determination circuit 31 outputs a determination result signal indicating that the motor terminal voltage is equal to or less than the voltage reference value to the drive signal hold circuit 32.

[0045] However, even when the motor terminal voltage determination circuit 31 is instructed to be turned off, it may output a determination status output indicating whether or not the motor terminal voltage exceeds the voltage reference value to the CPU 5. Thus, the CPU 5 can monitor whether or not the motor terminal voltage exceeds the voltage reference value even when the function of the motor terminal voltage determination circuit 31 is stopped. Therefore, even when the function of the motor terminal voltage determination circuit 31 is set to off, the CPU 5 can switch the function of the motor terminal voltage determination circuit 31 on depending on the situation.

[0046] Next, an example of the operation of the control unit CU1 according to this embodiment will be described. FIG. 3 is a flowchart showing an example of the operation of the control unit CU1 according to this embodiment. (Step S02) The control unit CU1 starts operation when an ignition signal indicating activation is input. The CPU 5 receives torque sensor information from the torque sensor 22 and vehicle information from the CANBUS 23. (Step S04) The CPU 5 calculates an assist current value to be supplied to the motor winding 17M based on the torque sensor information and the vehicle information. The assist current value corresponds to a current value required to generate an assist torque by rotating the motor 17. The assist torque corresponds to a torque adjustment amount for providing a target torque based on the steering torque and the vehicle information.

[0047] (Step S06) The CPU 5 performs assist control based on the calculated assist current value. Here, the CPU 5 notifies the drive circuit 12 of the assist current value for the motor winding 17M. The drive circuit 12 generates a switching signal for supplying three-phase AC power having the assist current value notified by the CPU 5. The drive circuit 12 outputs the generated switching signal to the inverter 14. The inverter 14 supplies the three-phase AC power to the motor winding 17M via the motor relay 15 in accordance with the switching signal input from the drive circuit 12. The motor winding 17M rotates the rotor by an induced magnetic field based on the three-phase AC power supplied from the drive circuit 12.

[0048] (Step S08) The drive circuit 12 monitors the operating status of the inverter 14 and determines whether an abnormality has occurred. If an abnormality is detected in the inverter 14 (YES in step S08), the drive circuit 12 outputs abnormality detection information indicating the abnormality detection to the CPU 5. Then, the process proceeds to step S10. If no abnormality is detected (NO in step S08), the process returns to step S02. Thus, assist control continues until an abnormality occurs in the inverter 14. (Step S10) The CPU 5 outputs operation mode information indicating an abnormality mode to the motor relay drive circuit 10, the power supply relay drive circuit 11, and the drive circuit 12. The motor relay drive circuit 10, the power supply relay drive circuit 11, and the drive circuit 12 issue OFF commands to all switching elements of the motor relay 15, the power supply relay 13, and the inverter 14, respectively.

[0049] (Step S12) If the motor relay / inverter drive circuit 18 is operating (YES in step S12), the process proceeds to step S14. If the operation of the motor relay / inverter drive circuit 18 is stopped (NO in step S12), the process of FIG. 3 ends. (Step S14) The motor terminal voltage determination circuit 31 of the motor relay / inverter drive circuit 18 determines whether the motor terminal voltage exceeds a predetermined voltage reference value. If it is determined that it exceeds the predetermined voltage reference value (YES in step S14), the process proceeds to step S16. If it is determined that it does not exceed the predetermined voltage reference value (NO in step S14), the process of step S14 is repeated. (Step S16) The inverter upper-stage off drive circuit 33 outputs a switching signal to the inverter 14 indicating an off command for the upper-stage switching elements of all phases. The inverter lower-stage on drive circuit 34 outputs a switching signal to the inverter 14 indicating an on command for the lower-stage switching elements of all phases. The motor relay on drive circuit 35 outputs a switching signal to the motor relay 15 indicating an on command for the switching elements.

[0050] (Step S18) The motor terminal voltage determination circuit 31 determines whether the motor terminal voltage is equal to or less than the reference voltage value. If it is determined that the motor terminal voltage is equal to or less than the reference voltage value (YES in step S18), the process proceeds to step S20. If it is determined that the motor terminal voltage exceeds the reference voltage value (NO in step S18), the process of step S18 is repeated. (Step S20) The inverter upper-stage OFF drive circuit 33 stops outputting switching signals to the inverter 14 indicating OFF commands to the upper-stage switching elements of all phases. The inverter lower-stage ON drive circuit 34 stops outputting switching signals to the inverter 14 indicating ON commands to the lower-stage switching elements of all phases. The motor relay ON drive circuit 35 stops outputting switching signals to the motor relay 15 indicating ON commands to the switching elements. This instructs the upper-stage switching elements of the inverter 14 to be released from the OFF state, the lower-stage switching elements of the inverter 14 to be released from the ON state, and the switching elements of the motor relay 15 to be released from the ON state. Then, the process returns to step S12.

[0051] Therefore, even if the power supply from the power supply 20 is cut off, the motor relay / inverter drive circuit 18 according to this embodiment can operate using power supplied from the motor terminals based on the back electromotive force generated by the rotation of the motor 17. If an off failure occurs in the power supply relay drive circuit 11, the motor relay drive circuit 10, or the like, or if the motor angle sensor 16 or the CPU 5 fails, the power supply from the power supply 20 to the motor 17 will be cut off. Even in such cases, the motor relay / inverter drive circuit 18 can continue to operate.

[0052] Furthermore, with the motor relay / inverter drive circuit 18, when the motor terminal voltage becomes high due to high-speed rotation of the motor 17, a regenerative current path can be formed using the motor relay 15 and the lower-stage switching elements of the inverter 14. As a result, back electromotive force is generated by electromagnetic induction caused by the rotation of the motor 17, and the resulting braking force can reduce the rotation speed. Furthermore, with the motor relay 15 and the lower-stage switching elements of the inverter 14, the electrical resistance of the regenerative current path is kept relatively low, so a strong induced magnetic field is generated in the motor winding 17M. The strong induced magnetic field strengthens the braking force, allowing the rotation speed of the motor 17 to be reduced quickly.

[0053] Second Embodiment Next, a second embodiment of the present disclosure will be described. Fig. 4 is a diagram showing a configuration example of an electronic control device according to this embodiment. In the example of Fig. 2, the electronic control device is configured as a control unit CU2 for a vehicle. The control unit CU2 is applied to steering assistance by an electric power steering device PS2. The following description will mainly focus on differences from the first embodiment.

[0054] The control unit CU2 includes a control unit 6, a power supply relay 13, an inverter 14, a motor relay 15, and a motor 17. The control unit CU2 is connected to a power supply 20, an ignition mechanism IG21, a torque sensor 22, and a CANBUS 23. The control unit 6 includes a power supply unit 6S, a motor terminal voltage determination unit 6MV, a motor relay drive unit 6MD, a power supply relay drive unit 6PD, an inverter drive unit 6I, an abnormality monitoring unit 6M, and a motor angle detection unit 6A.

[0055] The power supply unit 6S has the same function as the power supply circuit 30 (FIG. 1). That is, the power supply unit 6S distributes power supplied from the power supply 20 to each device in the control unit CU2 (including other devices constituting the control unit 6). However, the power supply unit 6S can operate the control unit 6 using the motor terminals as a power supply source. The power supply unit 6S has a configuration similar to that of the power supply circuit 30 (FIG. 2), for example. That is, the power supply unit 6S has a rectifying element and a capacitor, and stores power supplied from the motor terminals in the capacitor. The power stored in the capacitor is discharged to each device in the control unit 6.

[0056] The motor terminal voltage determination unit 6MV has the same function as the motor terminal voltage determination circuit 31 (FIG. 2). That is, the motor terminal voltage determination unit 6MV determines whether the motor terminal voltage of any phase exceeds a predetermined voltage reference value, and outputs a determination result signal indicating the determination result to the motor relay drive unit 6MD and the inverter drive unit 61. The motor terminal voltage determination unit 6MV continues to output the determination result signal indicating that the motor terminal voltage exceeds the predetermined voltage reference value until a predetermined fixed time has elapsed since the motor terminal voltage became equal to or lower than a set voltage.

[0057] The motor relay drive unit 6MD has the same function as the motor relay drive circuit 10 (FIG. 1). The power relay drive unit 6PD has the same function as the power relay drive circuit 11 (FIG. 1). The inverter drive unit 6I has the same function as the assist control by the CPU 5 (FIG. 1) and the same function as the inverter drive circuit 12I (FIG. 1).

[0058] The abnormality monitoring unit 6M has the same functions as the abnormality detection unit 12A (FIG. 1) and the abnormality monitoring unit 5A (FIG. 1). The abnormality monitoring unit 6M notifies the motor relay driving unit 6MD, the power supply relay driving unit 6PD, and the inverter driving unit 6I of the detected abnormality detection information. The motor angle detection unit 6A includes a motor angle sensor. The motor angle detection unit 6A also calculates the motor rotation speed and the motor rotation direction based on the motor angle using a method similar to that of the CPU 5 (FIG. 1). The motor angle detection unit 6A notifies the inverter driving unit 6I of the calculated motor rotation speed.

[0059] When the motor relay drive unit 6MD receives a judgment result signal from the motor terminal voltage judgment unit 6MV indicating that the motor terminal voltage exceeds the voltage reference value, the motor relay drive unit 6MD generates a switching signal indicating an ON command to the switching element of the motor relay 15, and outputs the generated switching signal to the motor relay 15 regardless of whether an abnormality has been detected at that time.

[0060] The inverter driving unit 6I generates, instead of switching signals related to assist control, switching signals indicating an OFF command to the upper-stage switching elements of the inverter 14 and switching signals indicating an ON command to the lower-stage switching elements of the inverter 14. The inverter driving unit 6I outputs the generated switching signals to the inverter 14.

[0061] The whole or a part of the control unit 6 can also be regarded as a drive system for driving the motor 17 by controlling part or all of the power supply relay 13, the motor relay 15, and the inverter 14. The functions of the control unit 6 or each of the components constituting the control unit 6 may be realized by a computer system provided in the control unit CU2, or may be realized by dedicated hardware. The computer system has one or more CPUs and realizes the functions by executing processes instructed by commands written in a predetermined program. An existing microcomputer chip may be used as such a computer system.

[0062] Therefore, even if the power supply from the power source 20 is cut off, the control unit 6 according to this embodiment can operate using power supplied from the motor terminals based on the back electromotive force generated by the rotation of the motor 17. Even if the power supply is cut off due to a fault, the control unit 6 can continue to operate. Furthermore, when the motor 17 rotates at high speed based on the motor terminal voltage, the control unit 6 can configure a regenerative current path using the motor relay 15 and the lower-stage switching elements of the inverter 14. As a result, a braking force is generated by the induced electromotive force caused by the rotation of the motor 17, and the rotation speed can be reduced.

[0063] The control units CU1 and CU2 according to the embodiments of the present disclosure may be configured with dedicated hardware or may include a general-purpose computer system. A computer system generally includes a processor and a storage medium. The processor may read a program non-temporarily stored in the storage medium and execute the read program to implement the functions of each component of the control units CU1 and CU2 in cooperation with the storage medium and other hardware. While the above description primarily focuses on the case where the processor is a CPU, this is not a limitation. The processor may also be any of various integrated circuits that execute processing instructed by instructions written in a program. The motor 17 and motor angle sensor 16 may be omitted from the control units CU1 and CU2, and may be provided separately from the control units CU1 and CU2 in the electric power steering devices PS1 and PS2. While the above description focuses on the case where the control units CU1 and CU2 are applied to an electric power steering device for a vehicle, this is not a limitation. The control units CU1 and CU2 may be applied to equipment and structures that use motors as power sources, such as railroad cars, bicycles, elevators, robots, and conveyors.

[0064] As described above, the electronic control device (e.g., control units CU1 and CU2) according to the present disclosure is an electronic control device that drives and controls the motor 17, and includes: an inverter 14 that supplies power to the motor 17; a power supply relay 13 that connects and disconnects the power supply 20 and the inverter 14; a motor relay 15 that connects and disconnects the inverter 14 and the motor 17; and a drive system (e.g., a motor terminal voltage determination circuit 31, a motor relay drive circuit 10, a power supply relay drive circuit 11, an inverter drive circuit 12I, a motor relay / inverter drive circuit 18, a motor terminal voltage determination unit 6MV, an inverter drive unit 6I, a power supply relay drive unit 6PD, and a motor relay drive unit 6MD) that detects the motor terminal voltage of the motor 17, and, when the motor terminal voltage exceeds a predetermined voltage reference value, disconnects the inverter 14 from the power supply relay 13 and connects it to the potential reference point, and connects the inverter 14 and the motor 17 to the motor relay 15. With this configuration, when the detected motor terminal voltage exceeds the voltage reference value, the connection between the inverter 14 and the power supply relay 13 is interrupted, the inverter 14 is connected to the potential reference point, and the inverter 14 is connected to the motor 17. As a result, a regenerative current path for the motor 17 is formed by the motor relay 15 and the inverter 14. A braking force is generated in the motor 17 due to the back electromotive force generated by the rotation of the motor 17, causing the rotation speed to decrease. This prevents the back electromotive force generated by the high-speed rotation of the motor 17 from applying a voltage exceeding the withstand voltage to circuit elements constituting the inverter 14 and the like. This in turn reduces or avoids the risk of circuit element failure.

[0065] The above electronic control device may be realized as follows. When an abnormality is detected, the drive system may cause the inverter to stop supplying power to the motor, cause the power supply relay to disconnect the power supply from the inverter, and disconnect the inverter from the motor, and when the motor terminal voltage exceeds a voltage reference value, prioritize disconnecting the inverter from the power supply relay, connecting the inverter to the potential reference point, and connecting the inverter to the motor. When no abnormality is detected and the motor terminal voltage exceeds the voltage reference value, the drive system may prioritize disconnecting the inverter from the power supply relay, connecting the inverter to the potential reference point, and connecting the inverter to the motor. The above electronic control device may include a power supply circuit that uses the motor terminal of the motor as a power supply source and supplies power to the drive system.

[0066] The power supply circuit may be capable of supplying power to the drive system for a certain period of time or more after the motor terminal voltage drops below a predetermined lower voltage limit. The electronic control device may include a signal holding circuit that holds a determination result indicating that the motor terminal voltage exceeds a voltage reference value for a certain period of time or more after the motor terminal voltage falls below the voltage reference value. The drive system may reject a determination result indicating that the motor terminal voltage exceeds the voltage reference value in response to a predetermined instruction (e.g., function off). The drive system may be capable of outputting a determination result indicating whether the motor terminal voltage exceeds the voltage reference value. The electronic control device may include a processor that realizes the functions of the drive system.

[0067] According to the electronic control device according to the present disclosure, the risk of circuit elements failing due to the back electromotive force of the motor can be reduced or prevented.

[0068] CU1, CU2...control unit, PS1, PS2...electric power steering device, 1...power supply circuit, 2...IG I / F circuit, 3...torque sensor I / F circuit, 4...CAN communication circuit, 5...CPU, 6...control unit, 10...motor relay drive circuit, 11...power supply relay drive circuit, 12...drive circuit, 13...power supply relay, 14...inverter, 15...motor relay, 16...motor angle sensor, 17...motor, 18...motor relay / inverter drive circuit, 20...power supply, 21...ignition mechanism IG, 22...torque sensor, 23...CANBUS, 30...power supply circuit, 31...motor terminal voltage determination circuit, 32...drive signal hold circuit, 33...inverter upper stage off drive circuit, 34...inverter lower stage on drive circuit, 35...motor relay on drive circuit

Claims

1. An electronic control device for driving and controlling a motor, comprising: an inverter for supplying power to the motor; a power supply relay for connecting and disconnecting a power supply to the inverter; a motor relay for connecting and disconnecting the inverter to the motor; and a drive system for detecting a motor terminal voltage of the motor, and when the motor terminal voltage exceeds a predetermined voltage reference value, disconnecting the inverter from the power supply relay and connecting it to a potential reference point, and connecting the inverter to the motor relay.

2. The electronic control device according to claim 1, wherein, when an abnormality is detected, the drive system causes the inverter to stop supplying power to the motor, causes the power supply relay to cut off the connection between the power supply and the inverter, and cuts off the connection between the inverter and the motor, and when the motor terminal voltage exceeds the voltage reference value, prioritizes the cutting off of the inverter and the power supply relay, the connection of the inverter and the potential reference point, and the connection of the inverter and the motor.

3. The electronic control device according to claim 1, wherein, when no abnormality is detected and the motor terminal voltage exceeds the voltage reference value, the drive system prioritizes disconnecting the inverter from the power supply relay, connecting the inverter to the potential reference point, and connecting the inverter to the motor.

4. The electronic control device according to claim 1, further comprising a power supply circuit that uses the motor terminals of the motor as a power supply source and supplies power to the drive system.

5. The electronic control device according to claim 4, wherein the power supply circuit is capable of supplying power to the drive system for a certain period of time or more after the motor terminal voltage drops below a predetermined lower voltage limit.

6. The electronic control device according to claim 5, further comprising a signal holding circuit that holds the determination result indicating that the motor terminal voltage exceeds the voltage reference value for a certain period of time or more after the motor terminal voltage falls below the voltage reference value.

7. The electronic control device according to claim 5, wherein the drive system, in response to a predetermined instruction, rejects a determination result indicating that the motor terminal voltage exceeds the voltage reference value.

8. The electronic control device according to claim 5, wherein the drive system is capable of outputting a determination result as to whether or not the motor terminal voltage exceeds the voltage reference value.

9. The electronic control device according to claim 1, further comprising a processor that implements the functions of the drive system.

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