JPH0923683A - Controller of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller of a motor which can improve further the reliability thereof, by sensing the presence of the abnormality of a current sensor itself for sensing the driving current of the motor. SOLUTION: A driving motor 1 of a power steering device is controlled in a PWM way by a control portion 4. When the driving current of the motor 1 is zero, a monitoring current is fed from a constant-current feeding circuit 12 to a current sensor 8 to sense the presence of the abnormality of the current sensor 8 itself on the basis of the sensed value of the monitoring current by the current sensor 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a drive motor such as a power steering device.

[0002]

2. Description of the Related Art Conventionally, as this type of control device,
For example, the one described in JP-A-2-81769 is known.

In such a device, the drive current of the drive motor of the power steering device is detected and monitored by a current sensor, and when the drive current exceeds a rated value, the drive circuit of the drive motor is automatically cut off. It has become. Further, when the drive current of the drive motor greatly exceeds the rated value, the electromagnetic clutch shuts off the transmission system of the drive force of the power steering device.

[0004]

The above-mentioned conventional device is not equipped with a means for determining abnormality of the current sensor itself for detecting the drive current of the drive motor.

An object of the present invention is to provide a motor control device capable of further improving reliability by detecting whether or not there is an abnormality in the current sensor itself which detects the drive current of the motor.

[0006]

According to a first aspect of the present invention, there is provided a motor control device which detects a drive current of an electric motor by a current sensor and controls the electric motor based on the detected current. In the control device, when a drive current is not supplied to the electric motor, a monitor current supply unit that supplies a monitor current for detection to the current sensor, and the current sensor when the monitor current is supplied to the current sensor. And a monitoring means for monitoring the change in the detected current.

According to a second aspect of the present invention, there is provided the motor control device according to the first aspect, wherein the monitoring current supply means is the current sensor when the pulse-width-modulated drive current of the electric motor is zero. It is characterized in that a monitoring current is supplied to.

According to a third aspect of the present invention, in the motor control device according to the first or second aspect, the monitoring means has a predetermined detection current of the detection sensor when the monitoring current is supplied to the current sensor. It is characterized in that the driving of the electric motor is stopped when it is out of the range.

According to a fourth aspect of the present invention, in the motor control device according to any one of the first to third aspects, the electric motor is a drive motor of a power steering device.

According to a first aspect of the present invention, the motor control device supplies a monitoring current to a current sensor for detecting the driving current when the driving current is not supplied to the electric motor, and the monitoring current is supplied to the current sensor. Is detected, the presence or absence of abnormality of the detection sensor itself is detected.

According to a second aspect of the present invention, the motor control device supplies the monitoring current to the current sensor when the drive current of the pulse width modulated drive motor is zero.
The presence or absence of abnormality of the detection sensor itself is detected during drive control of the drive motor.

A motor control device according to a third aspect of the present invention automatically stops the motor when the detected value of the current sensor when the monitoring current is supplied deviates from a predetermined range.

A motor control device according to a fourth aspect of the present invention controls a drive motor of a power steering device.

[0014]

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

(First Embodiment) FIGS. 1 and 2 are views for explaining a first embodiment of the present invention. The present embodiment is an application example as a control device in which a drive motor of an electric power steering device is a control target.

FIG. 1 is a circuit configuration diagram of a main part of the control device. In FIG. 1, reference numeral 1 denotes a drive motor of a power steering device, which includes four large current transistors 2A, 2B,
It is driven in the normal direction or the reverse direction by the switching operation of 2C and 2D. The transistors 2A and 2B are selectively turned on so as to determine the rotation direction of the motor 1, and the transistors 2C and 2D are on / off controlled with a duty corresponding to a pulse width modulated (PWM) drive signal. That is, the transistor 2A is turned on and the transistor 2C is controlled to be turned on / off, whereby the motor 1 rotates in one direction, and conversely, the transistor 2B is turned on.
Then, the transistor 2D is ON / OFF-controlled, so that the motor 1 rotates in the other direction. 3
Is a vehicle-mounted battery that supplies power to the drive circuit of the motor 1 and other circuits.

Reference numeral 4 is a control unit in the form of a microcomputer, which inputs detection signals from various sensors provided in the electric power steering system from an interface circuit 5 and drives and controls the motor 1 based on these detection signals. That is, the control unit 4 controls the corresponding transistors 2A, 2B, 2C, 2D by the driver circuits 6, 7, and determines the duty of the PWM output for driving the transistors 2C, 2D based on the detection signals of various sensors. . A resistance having a low resistance value is connected as a current sensor 8 in the drive circuit of the motor 1, and a voltage corresponding to the drive current of the motor 1 is output from a terminal of the resistance having the low resistance value. ing. Then, based on the output voltage of the current sensor 8, the overcurrent detection circuit 9 detects whether the drive current of the motor 1 has exceeded a predetermined value. The overcurrent detection circuit 9 outputs an "H" level signal when the drive current of the motor 1 is below the rated value, and outputs an "L" level signal when the drive current exceeds the rated value. Is set to.

The output signal of the overcurrent detection circuit 9 is input to the AND circuits 10A and 10B. The AND circuit 10A has a P for controlling the ON / OFF of the transistor 2C.
The logical product of the WM output and the output of the overcurrent detection circuit 9 is output to the driver circuit 7, while the AND circuit 10B outputs the PWM output for controlling the ON / OFF of the transistor 2D and the output of the overcurrent detection circuit 9. The logical product of and is output to the driver circuit 7. Normally, since the output of the overcurrent detection circuit 9 is at the “H” level, the transistors 2C and 2D are ON / OFF controlled based on the PWM signal from the control unit 4. Further, the output voltage of the current sensor 8 is converted into a digital signal by the current monitor interface circuit 11 as a monitoring means and input to the control unit 4 as a current monitor signal.

Reference numeral 12 denotes a constant current supply circuit as a monitoring current supply means, which is an ON / OFF control signal S1 for the control section 4.
Based on the above, a constant current as a monitoring current is supplied to the current sensor 8. The control signal S1 is the PWM-controlled motor 1
Drive current becomes zero, that is, the transistor 2C,
Constant current supply circuit 12 is turned on when 2D is turned off
As a state, a constant current is supplied to the current sensor 8.

Next, the operation will be described.

Normally, since the drive current of the motor 1 is less than the rated value, the output of the overcurrent detection circuit 9 becomes "H" level as described above, and the transistor 2C is output based on the PWM output from the controller 4. Alternatively, 2D is ON / OFF controlled, and the motor 1 is normally or reversely controlled according to which of the transistors 2A and 2B is ON. During such normal drive control, when the overcurrent detection circuit 9 detects an overcurrent greater than or equal to the rated value, its output becomes the “L” level and the drive circuit of the motor 1 is shut off. Further, the control unit 4 monitors the detected current of the current monitor interface circuit 11, and when the detected current exceeds a predetermined value, the control unit 4 takes measures such as disconnecting the drive system of the steering device with an electromagnetic clutch.

During normal drive control of the motor 1, the control section 4 supplies a monitoring current to the current sensor 8,
The current detected by the current monitor interface circuit 11 is monitored. FIG. 2 is a flowchart for explaining such a monitoring operation of the control unit 4.

During normal motor drive control for turning on / off the PWM output (steps S1, 2, 3, 4),
When the PWM output is OFF, as described above, the control unit 4 turns on the constant current supply circuit 12 and supplies the monitoring current to the current sensor 8 (step S5). The monitored current is detected by the current sensor 8, and the detected current is input to the control unit 4 by the current monitor interface 11. When the detected current is within the predetermined normal range, the control unit 4 turns off the constant current supply circuit 12 (steps S6 and 7), and then returns to the previous step S1.
On the other hand, when the detected current is out of the predetermined normal range, it is determined that the current sensor 8 has an abnormality, and the predetermined fail-safe control is started (step S8).

(Second Embodiment) FIG. 3 is a diagram for explaining a second embodiment of the present invention. Only the configuration of the constant current supply circuit 12 is different from the first embodiment described above. Be different.

The constant current supply circuit 12 in this example supplies a constant current as a monitoring current to the current sensor 8 when the drive current of the PWM-controlled motor 1 becomes zero based on the control signal S1. Has become. That is, the transistor 12A is controlled by the control signal S1 when the monitoring current is supplied.
ON / OFF control is performed, and when it is ON, the transistor 12B is also turned ON, the power supply voltage of the battery 3 and the resistance 1
The constant current determined by 2C is supplied to the current sensor 8.

Therefore, the constant current supply circuit 12 in this embodiment can supply the monitoring current to the current sensor 8 at the same timing as in the above-mentioned embodiments. In addition, in FIG. 3, 12D and 12E are resistors.

(Third Embodiment) FIG. 4 is a diagram for explaining a third embodiment of the present invention. The present embodiment is an application example as a control device of the hydraulic pump motor 1 of the power steering device, and the same parts as those in the above-described embodiments are designated by the same reference numerals and the description thereof will be omitted.

The motor 1 to be controlled in this embodiment is
ON / OFF of the transistor 2 based on the PWM output of the control unit 4
When the transistor 2 is OFF by PWM control and the transistor 2 is OFF, the constant current supply circuit 12 supplies a constant current as a monitoring current to the current sensor 8 based on the control signal S1. Therefore, it is possible to monitor whether or not the current sensor 8 is abnormal, as in the above-described embodiment. Reference numeral 10 is an AND circuit, and 20 is a diode.

[0029]

The motor control device according to the first aspect of the present invention, when the drive current is not supplied to the electric motor,
By supplying the monitoring current to the current sensor for detecting the drive current and detecting the monitoring current, it is possible to detect whether or not there is an abnormality in the detection sensor itself and further improve the reliability.

According to the second aspect of the present invention, the motor control device supplies the monitoring current to the current sensor when the drive current of the pulse width modulated drive motor is zero.
It is possible to reliably detect the presence or absence of an abnormality in the detection sensor itself during drive control of the drive motor.

The motor control device according to a third aspect of the present invention automatically stops the motor when the detected value of the current sensor when the monitoring current is supplied deviates from the predetermined range. The controllability of the motor can be improved.

In the motor control device according to the fourth aspect of the present invention, the reliability of the power steering device can be further improved by controlling the drive motor of the power steering device.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a main part of a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the first exemplary embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a main part of a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram of a main part of a third embodiment of the present invention.

[Explanation of symbols]

 1 Motor 2A, 2B, 2C, 2D Transistor 3 Battery 4 Control Section 8 Current Sensor 9 Overcurrent Detection Circuit 11 Current Monitor Interface Circuit (Monitoring Unit) 12 Constant Current Supply Circuit (Monitoring Current Supplying Unit)

Claims (4)

[Claims] 1. A motor control device for detecting a drive current of an electric motor by a current sensor and controlling the electric motor based on the detected current, wherein the current sensor is used when the drive current is not supplied to the electric motor. A monitoring current supply means for supplying a monitoring current for detection to the target, and a monitoring means for monitoring a change in the detection current of the current sensor when the monitoring current is supplied to the current sensor. Motor control device. 2. The monitoring current supply means supplies a monitoring current to the current sensor when the pulse-width-modulated drive current of the electric motor is zero. The motor control device described. 3. The monitoring means stops the driving of the electric motor when the detected current of the current sensor when the monitored current is supplied to the current sensor deviates from a predetermined range. The motor control device according to claim 1 or 2. 4. The motor control device according to claim 1, wherein the electric motor is a drive motor of a power steering device.