JP2007056704A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device capable of driving a motor even if a semiconductor switch is broken open.
Of two terminals connected to each other, a series motor 7 in which the terminal 19 is connected to a battery is connected to the terminal 20 and an open point when turned on, and to the ground when the terminal 20 is turned off. When the relay 8 is connected, the FET 20 that connects the terminal 20 and the ground when turned on, the FET 13 that shuts off the terminal 20 and the ground when turned off, and any one of predetermined conditions is satisfied, When the relay 8 is turned off and all the predetermined conditions are not satisfied, the relay 8 is turned on, and the control unit 18 that performs PWM control of the FET 13 is provided. The series motor 7 is provided between the terminal 19 and the terminal 20. A driving force is given by the current flowing, and the predetermined condition includes an open circuit failure of the FET 13.
[Selection] Figure 1

Description

  The present invention relates to a motor control device that is mounted on a vehicle and performs PWM (Pulse Width Modulation) control.

  Patent Document 1 describes a technique for PWM control of a semiconductor switch, that is, a technique for turning on and off a semiconductor switch at a desired frequency and duty ratio. Here, the frequency is the number of times that a unit operation consisting of one on operation and one off operation is performed in unit time, and the duty ratio is one on time and one off time. Ratio. An example of the semiconductor switch is an FET (Field Effect Transistor).

  In the technique described in Patent Document 1, since the driving force is applied to the motor only when the semiconductor switch is turned on, the rotation speed of the motor (that is, the rotation speed of the rotation shaft of the motor) is determined by the duty ratio. The higher the frequency, the smoother the drive. Therefore, the rotational speed of the motor is controlled by PWM control of the semiconductor switch. The fuel pump is driven by driving the motor.

Therefore, the technique described in Patent Document 1 calculates the optimum duty ratio according to the engine speed, and performs PWM control of the semiconductor switch at the optimum duty ratio, so that the motor can be operated at the optimum speed according to the engine speed. Drive. Thereby, fuel consumption improves.
JP-A-10-266920

  However, the conventional motor control device does not drive the motor when the semiconductor switch fails to open. Here, the open failure of the semiconductor switch means that the semiconductor switch does not turn on (that is, keeps the off state) even if an on signal is given to the semiconductor switch. For this reason, in the conventional motor control device, there is a possibility that the fuel pump may not be driven when the semiconductor switch is broken down, that is, the vehicle may not be able to run on its own.

  The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to provide a motor control device capable of driving a motor even if a semiconductor switch is broken open. There is.

  In order to achieve the above object, in the motor control device mounted on a vehicle, the invention according to the present application includes a motor in which one of the two motor terminals connected to the battery is connected to a battery, Connect the other motor terminal and the open point. When off, connect the other motor terminal to the ground. When on, connect the other motor terminal to the ground. When off, connect the other motor terminal to the ground. When any of the predetermined conditions is satisfied, the relay is turned off. When all the predetermined conditions are not satisfied, the relay is turned on and the semiconductor switch is turned on by PWM. And a control unit for controlling the motor, a driving force is given by a current flowing between one motor terminal and the other motor terminal, and a predetermined condition is Semiconductor switch involves the open-circuit failure.

  The invention according to the present application turns off the relay when the semiconductor switch fails to open. As a result, the battery, one motor terminal, the other motor terminal, and the ground are electrically connected, so that a driving force is applied to the motor. Therefore, the invention according to the present application can drive the motor even when the semiconductor switch has an open failure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a configuration of a motor control device 1 according to the present embodiment.

  The motor control device 1 is mounted on a vehicle and used for driving a fuel pump. The motor control device 1 includes a fuel pump relay 3, a series motor 7, a relay 8, FETs 13 and 15, an open / overcurrent / short-circuit detection unit 14, a reset IC 16, an abnormality determination unit 17, and a control unit 18. And comprising. The fuel pump relay 3 includes a coil 4 and terminals 5 and 6. The series motor 7 includes terminals 19 and 20 connected to each other. The relay 8 includes a coil 9 and terminals 10 to 12.

  The battery 2 is mounted on the vehicle. The negative terminal of the battery 2 is connected to the ground, and the positive terminal is connected to the terminal 5 of the fuel pump relay 3 via a fuse.

  One end of the coil 4 is connected to the ignition, and the other end is connected to the ground. The terminal 5 is connected to the positive terminal of the battery via a fuse, and the terminal 6 is connected to the terminal 19 of the series motor 7 and one end of the coil 9. When the fuel pump relay 3 is turned on, the positive terminal of the battery 2 is connected to the terminal 19 and one end of the coil 9, and when it is turned off, the fuel pump relay 3 is disconnected.

  The series motor 7 is given a driving force only when a current flows between the terminal 19 and the terminal 20. The series motor 7 is stopped in the initial state, and starts driving when a driving force is applied during the stop. The series motor 7 gradually decreases the rotation speed (that is, the rotation speed of the rotation shaft of the series motor 7) when no driving force is applied during driving, and stops when the speed becomes zero. The series motor 7 increases the rotation speed when a driving force is applied during driving. When the series motor 7 is driven, the fuel pump is driven. The terminal 20 is connected to the terminal 10 of the relay 8, the open / overcurrent / short-circuit detection unit 14, and the drain of the FET 13.

  The terminal 11 of the relay 8 is connected to the ground, and the terminal 12 is opened. The other terminal of the coil 9 is connected to the drain of the FET 15. When the fuel pump relay 3 is turned on and the relay 8 is turned off, the path R1 connecting the battery 2, the terminal 19, the terminal 20, and the point B is conducted, so that the terminal 19 and the terminal 20 of the series motor 7 are connected. Current flows between them. That is, a driving force is applied to the series motor 7. The relay 8 is turned off in the initial state.

  The gate of the FET 13 is connected to the open / overcurrent / short-circuit detection unit 14 and the control unit 18, and the source is connected to the ground. Accordingly, when the fuel pump relay 3 and the FET 13 are turned on, the path R2 connecting the battery 2, the terminal 19, the terminal 20, and the point C is conducted, so that the terminal 19 and the terminal 20 of the series motor 7 are connected. Current flows. That is, a driving force is applied to the series motor 7.

  The open / overcurrent / short-circuit detection unit 14 is connected to the drain of the FET 13, the gate of the FET 13, the control unit 18, and the abnormality determination unit 17. The open / overcurrent / short-circuit detection unit 14 detects the voltage at the point A, the current flowing through the point A, and the ON signal transmitted to the gate of the FET 13. The open / overcurrent / short-circuit detection unit 14 determines that the FET 13 has an open failure when the voltage at the point A becomes larger than the predetermined value V0 even though the ON signal is transmitted to the gate of the FET 13. Then, an open failure signal to that effect is output to the control unit 18 and the abnormality determination unit 17. The open / overcurrent / short-circuit detection unit 14 determines that an overcurrent is flowing to the point A for some reason when the current flowing to the point A becomes larger than the predetermined value I0, and the overcurrent indicating that. The signal is output to the control unit 18 and the abnormality determination unit 17. Here, as a cause of the overcurrent flowing to the point A, for example, a foreign object may be caught in the series motor 7 or a circuit around the series motor 7 may be short-circuited.

  The gate of the FET 15 is connected to the abnormality determination unit 17 and the control unit 18, and the source is connected to the ground. When the fuel pump relay 3 and the FET 15 are turned on, a current flows through the coil 9, so that the relay 8 is turned on. When the FET 15 is turned off, no current flows through the coil 9, so the relay 8 is turned off. .

  The reset IC 16 is connected to the abnormality determination unit 17 and the control unit 18. When an abnormality occurs in the control unit 18 for some reason, the reset IC 16 outputs an abnormal signal to that effect to the abnormality determination unit 17 and resets the control unit 18. Here, as a case where an abnormality occurs in the control unit 18, for example, a case where the control unit 18 does not operate according to a program is considered.

  The abnormality determination unit 17 turns off the relay 8 by turning off the FET 15 when an abnormality signal is given from the reset IC 16. Therefore, even if an abnormality occurs in the control unit 18, the abnormality determination unit 17 turns off the relay 8. Therefore, if the fuel pump relay 3 is on, the series motor 7 is continuously driven. The abnormality determination unit 17 turns off the FET 13 when an abnormality signal is given from the reset IC 16. Therefore, when an abnormality occurs in the control unit 18, no current flows through the FET 13, so that the FET 13 is protected from overcurrent.

  The control unit 18 is connected to the gates of the FETs 13 and 15, the open / overcurrent / short-circuit detection unit 14, the reset IC 16, and the abnormality determination unit 17. The controller 18 turns on the relay 8 by turning on the FET 15. When the relay unit 8 is turned on, the control unit 18 controls the rotation speed of the series motor 7 by PWM control of the FET 13. PWM control is performed by outputting an on signal and an off signal to the FET 13. When receiving an open failure signal from the open / overcurrent / short-circuit detector 14, the controller 18 continuously drives the series motor 7 by turning off the relay 8. When the control unit 18 is given an overcurrent signal from the open / overcurrent / short-circuit detection unit 14, the relay 8 and the FET 13 are turned off to continuously drive the series motor 7, while the FET 13 Protects against overcurrent.

  Next, the operation of the motor control device 1 will be described along the timing chart shown in FIG. In FIG. 2, the motor operation on means that the driving force is applied to the series motor 7, and the motor operation off means that the driving force is not applied to the series motor 7.

  When the ignition is turned on at time t0, the fuel pump relay 3 is turned on. Since the relay 8 is turned off, the path R1 becomes conductive, a current flows between the terminal 19 and the terminal 20, and the series motor 7 starts driving. Since a current continues to flow between the terminal 19 and the terminal 20, a driving force is always applied to the series motor 7. Therefore, the series motor 7 is driven at the maximum (ie, 100 percent) rotation speed.

  At time t1, the control unit 18 turns on the relay 8 and performs PWM control of the FET 13. When the relay 8 is turned on, the path R1 is interrupted, but when the FET 13 is PWM controlled, the path R2 is repeatedly turned on and off, so that the series motor 7 continues to drive. However, the rotation speed is determined by the duty ratio.

  When the ignition is turned off at time t2, the fuel pump relay 3 and the relay 8 are turned off. Since both the paths R1 and R2 are blocked, no driving force is applied to the series motor 7. The serial motor 7 gradually decreases the rotational speed and then stops.

  When the ignition is turned on at time t3, the motor control device 1 performs an operation at time t0.

  At time t31, the motor control device 1 performs an operation at time t1.

  At time t4, the open / overcurrent / short-circuit detecting unit 14 opens the FET 13 when the voltage at the point A becomes larger than the predetermined value V0 even though the ON signal is transmitted to the gate of the FET 13. It is determined that a failure has occurred, and an open failure signal to that effect is output to the control unit 18 and the abnormality determination unit 17. The open / overcurrent / short-circuit detection unit 14 determines that the overcurrent flows to the point A for some reason when the current flowing to the point A becomes larger than the predetermined value I0. The overcurrent signal is output to the control unit 18 and the abnormality determination unit 17. The control unit 18 turns off the relay 8 when an open failure signal or an overcurrent signal is given. Thereby, since the path R1 is conducted, the series motor 7 is continuously driven. In addition, since a current continues to flow between the terminal 19 and the terminal 20, a driving force is always applied to the series motor 7. Therefore, the series motor 7 is driven at the maximum rotational speed. The control unit 18 turns off the FET 13 when an overcurrent signal is given. Thereby, FET13 is protected from overcurrent. Since the open / overcurrent / short-circuit detection unit 14 outputs the open failure signal and the overcurrent signal to the abnormality determination unit 17 in addition to the control unit 18, the process performed by the control unit 18 at time t4 is determined to be abnormal. The part 17 may perform. Further, if the abnormality determination unit 17 is caused to perform the process at time t1, the control unit 18 is not necessary.

  When the ignition is turned off at time t5, the motor control device 1 performs an operation at time t2. The open / overcurrent / short-circuit detection unit 14 stops signal output.

  After the FET 13 is repaired and the cause of the overcurrent is removed, when the ignition is turned on at time t6, the motor control device 1 performs the operation at time t0. At time t61, the motor control device 1 performs an operation at time t1.

  When an abnormality occurs in the control unit 18 at time t <b> 7, the reset IC 16 outputs an abnormality signal to the abnormality determination unit 17 and resets the control unit 18. The abnormality determination unit 17 turns off the relay 8 when an abnormality signal is given from the reset IC 16. Therefore, since the path R1 is conducted, the series motor 7 is continuously driven. Further, the abnormality determination unit 17 turns off the FET 13. Thereby, FET13 is protected from overcurrent.

  When the control unit 18 returns at time t8, the reset IC 16 stops outputting signals. The control unit 18 turns on the relay 8 and performs PWM control on the FET 13.

  When the ignition is turned off at time t9, the motor control device 1 performs an operation at time t2.

  As described above, in the present embodiment, the motor control device 1 can drive the series motor 7 even if the FET 13 has an open failure. The motor control device 1 can drive the series motor 7 even if an overcurrent flows at the point A, and can protect the FET 13 from the overcurrent. The motor control device 1 can drive the series motor 7 even if an abnormality occurs in the control unit 18, and can protect the FET 13 from overcurrent. Since the current flowing through the FET 13 and the amount of heat generated by the FET 13 are reduced, the semiconductor switch can be made smaller, the structure for radiating the semiconductor switch can be simplified, and as a result, the motor control device 1 can be downsized. The manufacturing cost of the motor control device 1 can be reduced.

  Note that the present embodiment can be changed without departing from the spirit of the present invention. For example, the series motor 7 may drive a fan that cools the engine. In this case, as the cause of the overcurrent flowing to the point A, for example, the flooding lock of the series motor 7 can be considered.

It is a circuit diagram showing a motor control device concerning one embodiment of the present invention. It is a timing chart which shows the operation timing etc. by a motor control device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Motor control apparatus 2 ... Battery 3 ... Fuel pump relay 4 ... Coil 5, 6, 10-12, 19, 20 ... Terminal 7 ... Series motor 8 ... Relay 9 ... Coil 13, 15 ... FET
14 ... Open / overcurrent / short-circuit detector 16 ... Reset IC
17 ... Abnormality determination unit 18 ... Control unit

Claims (4)

In a motor control device mounted on a vehicle,
Of the two motor terminals coupled to each other, one motor terminal is connected to the battery, and
When on, connect the other motor terminal and the open point, and when off, connect the other motor terminal and the ground,
A semiconductor switch that connects the other motor terminal and the ground when on, and shuts off the other motor terminal and the ground when off;
A control unit that turns off the relay when any one of predetermined conditions is satisfied, and turns on the relay when all the predetermined conditions are not satisfied, and performs PWM control of the semiconductor switch. And comprising
The motor is given a driving force by a current flowing between the one motor terminal and the other motor terminal,
The motor control apparatus, wherein the predetermined condition includes an open failure of the semiconductor switch. The motor control device according to claim 1,
The predetermined condition includes that a current flowing through the semiconductor switch is larger than a predetermined value,
The control unit is a motor control device that turns off the relay and the semiconductor switch when a current flowing through the semiconductor switch becomes larger than the predetermined value. The motor control device according to claim 1 or 2,
A reset unit that resets the control unit when an abnormality occurs in the control unit;
A motor control device comprising: an abnormality determination unit that turns off the relay when the reset unit is activated. The motor control device according to claim 3, wherein
The abnormality determination unit is a motor control device that turns off the semiconductor switch when the reset unit is activated.

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