JP5432600B2 - Electronic control unit with built-in actuator - Google Patents

Description

  The present invention relates to an electronic control device that incorporates an actuator such as a motor and can perform various controls using the actuator. Here, the actuator is a general term for machines, mechanisms, and devices that convert various kinds of energy such as electricity and air pressure into mechanical motion, and includes a motor, a hydraulic cylinder, and the like.

  An electronic control device that controls a motor as an example of an actuator is used in various industrial fields. A conventional electronic control apparatus will be described with reference to FIG. 2. In this apparatus, a three-phase brushless motor 1 is used as an actuator. In order to supply a three-phase drive current to the brushless motor 1, a motor drive circuit 3 including a plurality of MOS-FETs is used.

  The power relay 5 switches whether the motor drive circuit 3 is connected to the battery power source 7 or not. The power supply relay 5 is turned on when the apparatus is operating, and is turned off when the apparatus is stopped. The MOS-FET included in the motor drive circuit 3 is controlled using a PWM signal output from the CPU 9 which is a control unit, and the phase from the motor drive circuit 3 to the brushless motor 1 is different by 2π / 3 in a sine wave shape. A changing three-phase driving current is output.

  When the brushless motor 1 is driven using the PWM signal in this way, the current flowing from the battery power supply 7 to the motor drive circuit 3 via the power supply relay 5 greatly fluctuates in a short time, and a current ripple is generated.

  Therefore, a capacitor 15 is provided between the power supply lines 11 and 13 to absorb this current ripple. The capacitor 15 accumulates charges, and discharges the accumulated charges when the current flowing from the battery power source 7 to the motor drive circuit 3 is insufficient. Thereby, current ripple can be absorbed.

  In the conventional electronic device, when the device is stopped, all the MOS-FETs included in the motor drive circuit 3 are controlled to be in an off state, and thereafter, the power relay 5 is in an off state. At this time, it is necessary to discharge the electric charge accumulated in the capacitor 15.

  Therefore, in this motor drive circuit 3, a resistor 17 is provided as a discharge circuit between the power supply lines 11 and 13. After the power supply relay 5 is turned off, the electric charge accumulated in the capacitor 15 is discharged through the resistor 17.

  The reason why the electric charge accumulated in the capacitor 15 is discharged when the power supply relay 5 is turned off is that when the power supply relay 5 is inspected for the next time when the power supply relay 5 is turned on, the inspection is performed if the electric charge is accumulated in the capacitor 15. This is because it cannot be done correctly.

  This failure inspection will be described.

  When the power supply relay 5 is controlled to be turned off by the control from the CPU 9, the power supply relay 5 may be welded and cannot be turned off. When the power relay 5 is normal, the terminal voltage Vcc of the power terminal of the motor drive circuit 3 is Vcc≈0V, but when the power relay 5 is welded, the terminal voltage Vcc of the power terminal is Vcc≈battery power. 5 voltage, for example, 12V. The CPU 9 diagnoses the state of the power supply relay 5 from the terminal voltage Vcc. This diagnosis requires that the capacitor 15 has been discharged.

  However, in the above configuration, when the resistor 17 is provided as a discharging circuit, a current flows through the resistor 17 even during the operation of the device, so that there are problems such as an increase in current consumption during device operation.

  As shown in FIG. 3, a circuit in which a resistor 17 and a switch 19 are connected in series can be provided as a discharging circuit. In the apparatus shown in FIG. 3, the switch 19 is turned on after the power supply relay 5 is turned off.

  In view of the above problems, as shown in FIG. 4, the charge accumulated in the capacitor 15 for absorbing the current ripple when the power is turned off is indicated by the arrow a → b in a part of the current path necessary for the rotation of the brushless motor 1. By discharging in the order of paths indicated by → c → d, the charge accumulated in the capacitor 15 for absorbing current ripple is discharged without using a dedicated circuit as shown in FIGS. Proposed.

JP 2006-21645 A JP 2004-330877 A JP 2008-94342 A

  However, in the apparatus shown in FIG. 4, since the brushless motor 1 is included in the discharge path, it is necessary to consider the behavior of the brushless motor 1, and there is a problem that the control in the CPU 9 is complicated.

  Accordingly, the present invention provides a device that can reduce current consumption during device operation and discharge a capacitor in a short time with simple control.

  In the electronic control device with built-in actuator according to the present invention, a power supply relay is connected in series in a power supply line between a battery power supply and a power supply terminal of the actuator drive circuit, and between the power supply terminal and the ground terminal of the actuator drive circuit. The both end electrodes of the capacitor are connected in parallel, and the power supply relay is diagnosed from the voltage value of the power supply terminal in the off-control state of the power supply relay when the battery power is turned on by the control unit. In the electronic control device with built-in actuator for discharging the accumulated charge through the discharge path, a coil is connected in series between the power supply terminal of the actuator drive circuit and the power supply relay, and the coil and the switch are connected to both end electrodes of the capacitor. Are connected in series to form the discharge path, and the power relay is turned off. It is on the occasion, and is characterized in that discharging the charges accumulated in the capacitor by turning on the switch.

  According to the present invention, when the battery power is off, the electric charge accumulated in the capacitor for absorbing current ripple is discharged through the switch. Therefore, the electric charge accumulated in the capacitor for absorbing current ripple can be discharged without using a resistor, so that the current consumption of the device can be reduced. In addition, the charge accumulated in the capacitor for absorbing current ripple when the power is off is not discharged through a part of the current path necessary for driving the actuator, so there is no need to consider the behavior of the actuator. , Control is simpler than before.

FIG. 1 is a diagram showing a circuit configuration of an electronic control device according to an embodiment of the present invention. FIG. 2 is a diagram showing a circuit configuration of a conventional electronic control device. FIG. 3 is a diagram showing a circuit configuration of another conventional electronic control apparatus. FIG. 4 is a diagram showing a circuit configuration of still another conventional electronic control device.

  Hereinafter, an actuator built-in electronic control device according to an embodiment of the present invention will be described with reference to the accompanying drawings. In this embodiment, description will be made by applying to a motor as an actuator, but the actuator is not limited to a motor. Further, the electronic control device of the embodiment is not limited to any device.

  FIG. 1 shows the circuit configuration of the above apparatus. Referring to FIG. 1, 1 is a brushless motor, 3 is a motor drive circuit, 5 is a power relay, 7 is a battery power supply, 9 is a CPU, 11 and 13 are hot and ground power lines, and 15 is a capacitor.

  In the embodiment, the power supply relay 5 is connected in series in the hot power supply line 11 between the battery power supply 7 and the power supply terminal Vcc of the motor drive circuit 3 as in the prior art, and the power supply terminal Vcc of the motor drive circuit 3 is connected to the power supply terminal Vcc. When both ends of the capacitor 15 are connected in parallel to the ground terminal Vg, the CPU 9 turns on the power supply relay 5 and turns on the battery power supply 7. In addition to diagnosing the power supply relay 5, when the power supply relay 5 is turned off, the charge accumulated in the capacitor 15 is discharged through a discharge path indicated by an arrow A in the figure.

  In the embodiment, the noise suppression coil 21 is connected in series between the power supply terminal Vcc of the motor drive circuit 3 and the power supply relay 5, and the noise suppression coil 21 and the discharge switch 23 are connected to both ends of the capacitor 15. Are connected in series to form a capacitor charge discharge path, and the CPU 9 turns on the discharge switch 23 to store the capacitor 15 when the power supply relay 5 is turned off to diagnose the power supply relay 5. Electric charges are discharged using the noise suppression coil 21 as a discharge load.

  In the above configuration, in the embodiment, the electric charge accumulated in the capacitor 15 for absorbing current ripple is discharged through the noise suppression coil 21 and the discharge switch 23 when the battery power supply 7 is turned off. The electric charge accumulated in 15 can be discharged without using a resistor, and the current consumption of the device can be reduced. In addition, since the electric charge accumulated in the capacitor 15 is not discharged through a part of the current path necessary for driving the motor when the power is turned off, it is not necessary to consider the motor behavior and the control is simpler than before. Turn into.

DESCRIPTION OF SYMBOLS 1 Brushless motor 3 Motor drive circuit 5 Power supply relay 7 Battery power supply 9 CPU (control part)
11, 13 Power line 15 Capacitor 21 Noise suppression coil 23 Discharge switch

Claims (1)

A power relay is connected in series in the power line between the battery power supply and the power supply terminal of the actuator drive circuit, and both end electrodes of the capacitor are connected in parallel between the power supply terminal of the actuator drive circuit and the ground terminal. Thus, when the battery power is turned on, the power relay is diagnosed from the voltage value of the power terminal in the power-off state of the power-supply relay, and at the time of power-off control of the power-supply relay, In the control device,
A coil is connected in series between the power supply terminal of the actuator drive circuit and the power supply relay, and the coil and the switch are connected in series to both end electrodes of the capacitor to form the discharge path. An electronic control device characterized in that, in the off control, the switch is turned on to discharge the accumulated charge of the capacitor.

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