JP2020048387A - Motor control device - Google Patents

Abstract

To enable execution of hardware reset without using an external mechanical relay at a motor control device.SOLUTION: A motor control device 1 comprises: a communication interface circuit 11 for exchanging communication signals P1 and P2 with a high-order controller 2; a drive circuit 15 that drives a motor; and a control circuit 12 that controls the drive circuit 15. The control circuit 12 is configured to receive a command at a pulse width of the communication signal P1 from the high-order controller 2 via the communication interface circuit 11. The control circuit 12 interprets the command to determine a control amount for the drive circuit 15 on the basis of the pulse width when the pulse width is in a first range (range of 10%≤W≤90%), and interprets the command to reset the control circuit 12 when the pulse width is in a second range (range of 0%<W<10% or 90%<W<100%).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor control device.

  2. Description of the Related Art In recent years, components mounted on automobiles, motorcycles, ships, and the like have a built-in microcomputer and are configured to perform detailed control by the components themselves. Command values are often given to these components by communication from a host controller. For communication between such components and the host controller, for example, pulse width modulation (PWM) can be used. Japanese Patent Laying-Open No. 2015-186260 (Patent Document 1) discloses an example in which PWM is used for communication between on-vehicle devices.

JP 2015-186260 A

  Conventionally, a power supply is turned on / off by a mechanical relay for an auxiliary device having a built-in motor such as an electric pump used for an automobile, a motorcycle, a ship, or the like. However, it is preferable that the mechanical relay is not provided from the viewpoints of reliability and space saving. In recent years, there has been a demand for an auxiliary device that is directly connected to the battery without passing through the mechanical relay.

  Conventionally, in order to initialize the auxiliary equipment when an error occurs in the auxiliary equipment, the host controller has performed a hardware reset in which the mechanical relay is turned off, the power is once cut off, and then the power is turned on again. As a result, a power-on reset when the power is turned on operates, and the auxiliary equipment is initialized. However, when a battery is connected to an accessory without passing through a mechanical relay, such a hardware reset cannot be performed, and some kind of accessory initialization method that can be executed by a host controller is required.

  Japanese Patent Laying-Open No. 2015-186260 (Patent Document 1) discloses a method of clearing data of a counter or the like using a PWM input, but does not mention a method of replacing hardware reset.

  The present invention is intended to solve such a problem, and its object is to provide an external mechanical relay in a motor control device mounted on an auxiliary machine including a motor used for an automobile, a motorcycle, a ship, or the like. The hardware reset can be executed without using it.

  The present disclosure relates to a motor control device. The motor control device includes a communication interface circuit for transmitting and receiving a communication signal to and from a host controller, a drive circuit for driving the motor, and a control circuit for controlling the drive circuit. The control circuit is configured to receive a command with a pulse width of a communication signal from the host controller via the communication interface circuit. When the pulse width is the width of the first range, the control circuit interprets that the command is to determine the control amount for the drive circuit based on the pulse width, and determines that the pulse width does not overlap the first range. If the width is two ranges, it is interpreted that the command is to reset the control circuit.

  Preferably, the motor control device further includes a watchdog timer circuit that resets the control circuit when a clear signal is not input from the control circuit for a certain period. The control circuit has a first mode in which a clear signal is repeatedly transmitted to the watchdog timer circuit, and a second mode in which transmission of the clear signal to the watchdog timer circuit is stopped, as operation modes. When the pulse width is in the second range, the control circuit transitions from the first mode to the second mode.

  More preferably, the control circuit transitions from the first mode to the second mode when the pulse width is repeated within the second range a predetermined number of times.

  Preferably, the control circuit monitors whether or not the drive circuit is operating normally, and notifies the host controller via the communication interface circuit that the abnormality has occurred when the drive circuit has an abnormality.

  According to the present invention, it is possible to realize a motor control device capable of performing hardware reset without using ON / OFF of a mechanical relay with a simple and inexpensive configuration.

FIG. 2 is a circuit diagram illustrating a configuration of a motor control device according to the present embodiment. 5 is a flowchart illustrating a motor monitoring process executed by a control circuit 12. 4 is a flowchart for explaining a process in which the motor control device 1 decodes a command given by a signal received from a host controller 2. FIG. 4 is a diagram illustrating a relationship between a duty ratio of a PWM signal and a motor current. FIG. 9 is an operation waveform diagram for explaining an example of a reset operation.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings below, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

  FIG. 1 is a circuit diagram showing a configuration of the motor control device according to the present embodiment. Referring to FIG. 1, motor control device 1 is connected to battery 5 and receives power supply voltage + B. The motor control device 1 controls the motor 3 according to a command from the host controller 2. The motor control device 1 receives an output of a rotation speed sensor 4 that detects the rotation speed of the motor 3, and monitors the operation of the motor 3.

  The motor control device 1 includes a communication interface circuit 11 for transmitting and receiving communication signals P1 and P2 to and from the host controller 2, a drive circuit 15 for driving the motor, and a control circuit 12 for controlling the drive circuit 15. The control circuit 12 includes a microprocessor, a memory, and the like.

  The control circuit 12 is configured to receive a command from the host controller 2 via the communication interface circuit 11 with the pulse width of the communication signal P1. When the pulse width is in the first range (10% ≦ W ≦ 90%), the control circuit 12 interprets that the command is to determine the control amount for the drive circuit 15 based on the pulse width. If the pulse width is the width of the second range that does not overlap the first range (a range included in 0% <W <10% or 90% <W <100%), the command resets the control circuit 12. Decipher it.

  In the configuration shown in FIG. 1, in order to reduce the number of components, the battery 5 is directly connected to the motor control device 1 without passing through a mechanical relay. Therefore, it is not possible to forcibly shut off the power supply to the motor control device 1 using a mechanical relay and to initialize the motor control device 1 by power-on reset as in the related art.

  However, in the present embodiment, since a part of the pulse width of the signal P1 for performing the PWM communication is assigned to the reset command, the host controller 2 forcibly sends the signal to the motor control device 1 using the mechanical relay. The motor control device 1 can be initialized without interrupting the power supply. Therefore, the motor 3 can be controlled with a configuration in which the mechanical relay is omitted, so that cost reduction and occupation space reduction can be realized. Further, if a mechanical relay is used, a problem such as welding may occur. However, if the configuration shown in FIG. 1 is used, the mechanical relay can be eliminated, so that the reliability of motor control can be improved.

  The motor control device 1 further includes a watchdog timer circuit 13 that resets the control circuit 12 when the input of the clear signal CLR from the control circuit 12 is not performed for a certain period. The control circuit 12 has, as operation modes, a first mode in which the clear signal CLR is repeatedly transmitted to the watchdog timer circuit 13 and a second mode in which the transmission of the clear signal CLR to the watchdog timer circuit 13 is stopped. When the pulse width is within the second range, the control circuit 12 transitions from the first mode to the second mode.

  More preferably, the control circuit 12 determines that the pulse width is a predetermined number of times that the pulse width is the width of the second range (the width of the range included in 0% <W <10% or 90% <W <100%). Then, a transition is made from the first mode to the second mode.

  Preferably, the control circuit 12 monitors whether or not the drive circuit 15 is operating normally. If an abnormality occurs in the drive circuit 15, the control circuit 12 informs the host controller 2 via the communication interface circuit 11 that an abnormality has occurred. Notify.

  FIG. 2 is a flowchart illustrating a motor monitoring process executed by the control circuit 12. The process of the flowchart of FIG. 2 is called and executed from the main routine of the motor control at regular intervals.

  Referring to FIGS. 1 and 2, control circuit 12 determines whether an error has been detected in step S1. For example, the control circuit 12 compares the current command sent to the drive circuit 15 with the rotation speed of the motor 3 detected by the rotation speed sensor 4 to determine whether or not the motor 3 is abnormal. Specifically, when the rotation speed is lower than the determination value while the motor current is flowing, it is determined that an abnormality has occurred in the drive circuit 15 or the motor 3. As a result, step-out of the motor 3 can be detected.

  In such a case, the control circuit detects a motor drive error (YES in S1), notifies the host controller 2 that a motor drive error has been detected in step S2, and returns the process to the main routine in step S3. . This notification is made by the signal P2 via the communication interface circuit 11. On the other hand, if no error is detected (NO in S1), the process returns to the main routine in step S3 without performing the process in step S2.

  In step S2 of FIG. 2, when an error is notified to the upper controller 2, the upper controller 2 transmits a reset command for initializing the motor controller 1 to the motor controller 1 using the signal P1. . For example, when the motor control device 1 is mounted on an automobile, it may be better to initialize the motor control device 1 while the vehicle is stopped. Therefore, when receiving a notification that a motor drive error has been detected, the host controller 2 thereafter transmits a reset command to the motor control device 1 at a time appropriate for initialization.

  FIG. 3 is a flowchart for explaining a process in which the motor control device 1 decodes what kind of command the signal received from the host controller 2 is. The process of the flowchart in FIG. 3 is called and executed from the main routine of the motor control at regular intervals.

  1 and 3, in step S11, the control circuit 12 detects the pulse width included in the signal P1 sent from the host controller 2, and calculates the pulse duty ratio. Depending on the duty ratio, the command indicated by the signal P1 may be a command for a control amount for the motor or a reset command for initializing the motor control device 1.

  FIG. 4 is a diagram illustrating the relationship between the duty ratio of the PWM signal and the motor current. When the duty ratio is 10% or more and 90% or less, signal P1 represents a command value of the motor current. When the duty ratio is within a predetermined range that does not overlap between 10% and 90%, the signal P1 indicates a reset command. The duty ratio indicating the reset command may be any range as long as it does not overlap the range indicating the motor current command value. For example, any range (for example, 4% or more and 5% or less) within the range shown by reset 1 in FIG. 4 may be used, and any range (for example, 94% or more and 95% or less) within the range shown by reset 2 in FIG. ) Is fine.

  Returning to FIG. 3 again, the control circuit 12 determines in step S12 whether the duty ratio indicated by the pulse width of the pulse included in the signal P1 corresponds to the reset command. If it does not correspond to the reset command (NO in S12), in step S13, the control circuit 12 drives the drive circuit 15 to supply a current value corresponding to the duty ratio of the pulse of the signal P1 based on the correspondence shown in FIG. Send a command to Although the duty ratio corresponds to the current in FIG. 4, the duty ratio may correspond to another control amount, for example, torque, rotation speed, and the like. Upon completion of the process in the step S13, the process proceeds to a step S14.

  On the other hand, if the duty ratio indicated by the pulse width of the pulse included in the signal P1 does not correspond to the reset command (NO in S12), the control circuit 12 determines in step S17 whether the reset command has continued N times (N is a natural number). Determine whether or not. Although N may be set to 1, for example, it is conceivable that noise of a pulse width corresponding to the reset command is accidentally added to the signal P1. Therefore, when N is set to 2 or more and the reset command is input plural times continuously, It is preferable to perform a self-reset. In addition, a combination of a small duty ratio and a large duty ratio such as less than 10% (for example, 5%) for the first time and more than 90% (for example, 95%) for the second time may be recognized as a reset command. In addition, in the combination, the order may be any.

  If the reset command is not consecutive N times in step S17, the process proceeds to step S14.

  In step S14, it is determined whether a predetermined time has elapsed since the previous transmission of the clear signal CLR to the watchdog timer circuit 13. If the predetermined time has elapsed in step S14, the control circuit 12 sends a clear signal CLR to the watchdog timer circuit 13 in step S15. The operation mode in which the clear signal CLR is periodically transmitted to the watchdog timer circuit 13 is referred to as a first mode. If the predetermined time has not elapsed in step S14, the process proceeds to step S16 without executing the process in step S15.

  By the processing of steps S14 and S15, the timer inside the watchdog timer circuit 13 is cleared at predetermined time intervals and does not overflow.

  On the other hand, if the reset command is input N times consecutively in step S17, the control circuit 12 stops transmitting the clear signal CLR to the watchdog timer circuit 13 in step S18. The operation mode in which the transmission of the clear signal CLR to the watchdog timer circuit 13 is stopped is referred to as a second mode. In step S18, the control circuit 12 changes the operation mode from the first mode to the second mode.

  Then, the timer inside the watchdog timer circuit 13 overflows after a while, and a reset signal is sent from the watchdog timer circuit 13 to the control circuit 12. As a result, when the control circuit 12 is reset, the drive circuit 15 also performs an initial operation with the reset, and it can be expected that the abnormality is eliminated.

  FIG. 5 is an operation waveform diagram for explaining an example of the reset operation. Referring to FIGS. 1 and 5, between times t0 and t2, the operation mode of control circuit 12 is the first mode, and signal P1 transmitted from host controller 2 has a duty ratio of 10% or more and 90% or less. Pulse signal. Then, the driving circuit 15 operates with a control amount corresponding to the pulse width. At this time, the count value of the internal counter of the watchdog timer circuit 13 does not reach the overflow value OVF due to the repeated transmission of the clear signal CLR.

  At time t3, when the control circuit 12 detects a motor abnormality and notifies the host controller 2 of the error, the host controller 2 sets the pulse width of the signal P1 to a width corresponding to the reset command and transmits a pulse repeated N times. Then, at time t5, the control circuit 12 changes the operation mode from the first mode to the second mode.

  Until time t5, the operation mode is the first mode, and since the clear signal CLR is sent to the watchdog timer circuit 13 at times t1, t2, and t4, the internal counter of the watchdog timer circuit 13 does not overflow. Was.

  However, when the operation mode changes from the first mode to the second mode at time t5, the control circuit 12 does not transmit the clear signal CLR to the watchdog timer circuit 13, so that at time t6, the internal counter overflows and the watchdog timer The circuit 13 sends a reset signal to the control circuit 12. As a result, it is expected that the control circuit 12 is reset, whereby the drive circuit 15 also performs the initial operation and the motor 3 returns to the normal state.

  As described above, according to the motor control device of the present embodiment, a reset can be performed from a higher-level controller that controls an auxiliary machine without using a mechanical relay. For this reason, a failure of the mechanical relay does not occur, so that the reliability is improved. Further, it is not necessary to newly add a terminal for resetting. Therefore, the size of the accessory can be reduced, and the cost of the accessory can be suppressed.

  The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 Motor control device, 2 host controller, 3 motors, 4 rotation speed sensors, 5 batteries, 11 communication interface circuit, 12 control circuit, 13 watchdog timer circuit, 15 drive circuit.

Claims (4)

A communication interface circuit for exchanging communication signals with the host controller;
A drive circuit for driving the motor;
A control circuit for controlling the drive circuit,
The control circuit is configured to receive a command with a pulse width of the communication signal from the host controller via the communication interface circuit,
When the pulse width is the width of the first range, the control circuit interprets that the command is to determine a control amount for the drive circuit based on the pulse width, and the pulse width is If the width of the second range does not overlap with the first range, the motor control device interprets that the command is to reset the control circuit. A watchdog timer circuit that resets the control circuit when a clear signal is not input from the control circuit for a certain period of time;
The control circuit has a first mode in which the clear signal is repeatedly transmitted to the watchdog timer circuit, and a second mode in which transmission of the clear signal to the watchdog timer circuit is stopped, as operation modes,
The motor control device according to claim 1, wherein the control circuit transitions from the first mode to the second mode when the pulse width is within the second range.   3. The motor control device according to claim 2, wherein the control circuit makes a transition from the first mode to the second mode when the pulse width is within the second range a predetermined number of times. 4.   The control circuit monitors whether the drive circuit is operating normally and, when an abnormality occurs in the drive circuit, notifies the upper controller via the communication interface circuit that an abnormality has occurred. The motor control device according to any one of claims 1 to 3.

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