JP2002234450A - Electric motor controlling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reduction of manufacturing workability and increase in costs due to complication of an output circuit structure for an off signal to four switching elements. SOLUTION: This electric motor controlling device is provided with a main processor unit 13 forming an electric current command value for assisting a DC motor 11 for a power steering and the four switching transistor elements 16-19 turning on/off a driving current to the DC motor on the basis of a control signal from the main processor unit. The main processor unit is provided with AND circuits 30 and 31 turning off only the two upstream side switching transistor elements 16 and 18 connected to a power source when an abnormal condition detecting signal is outputted from an abnormal condition detecting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device used for, for example, an electric power steering, and more particularly to a technique for stopping a switching element for turning on and off a drive signal for an electric motor.

[0002]

2. Description of the Related Art As a conventional motor control device of this type, for example, one described in Japanese Patent Application Laid-Open No. 5-185937 is known.

[0003] This motor control device is applied to a motor drive mechanism of an electric power steering device, and will be briefly described with reference to FIG. 4. According to the polarity of the current command value, four H-bridge type switching elements S
A current drive unit 1 for controlling W1 to SW4 by a pulse modulation method (PWM method) is provided.

Further, a motor line ground fault detection circuit 3 for detecting a voltage across the motor 2, a motor current detection circuit 4 for detecting a motor current from the voltage across the motor 2, and a detection result from the motor current detection circuit 4 And an overcurrent detection circuit 5 for inputting an overcurrent.

When the detection of the ground fault of the motor 2 is permitted, the voltage driving means 1 switches the switching elements SW1 to SW4.
Has the function of turning off all of the. Specifically, when the ground fault of the motor 2 is detected by the motor ground fault detecting circuit 3, the ground fault detection result is input to the CPU 6, and the output of the motor ground fault detecting circuit 3 is output through the OR gate 7. Is input to the drive control circuit 8, from which all the switching elements SW 1 to SW 4 are passed through the gate drive circuit 9.
Is turned off, the power supply to the motor 2 is cut off, and the driving is prohibited.

[0006]

However, in this conventional motor control device, the CPU 6 sends the signal to the drive control circuit 7 via the OR gate 7 in response to the detection signal from the motor line ground fault detection circuit 3 as described above. By turning off, for example, four AND circuits included therein, all four corresponding switching elements SW1 to SW
The power supply to W4 is cut off.

That is, four switching elements SW1
To turn off all the switches SW4, it is necessary to provide four AND circuits corresponding to the respective circuits in the drive control circuit 8, so that the circuit structure becomes complicated and the number of parts is inevitably increased. This has led to a reduction in manufacturing work efficiency and a rise in costs.

[0008]

SUMMARY OF THE INVENTION The present invention has been devised in view of the technical problems of the conventional devices, and the invention according to claim 1 turns on and off a drive current for an electric motor. Four switching elements connected in a bridge, abnormality detection means for detecting an abnormality of the motor control circuit, and when the abnormality detection signal is output from the abnormality detection means,
And stopping means for turning off only two upstream switching elements connected to the power supply among the two switching elements.

Therefore, according to the present invention, when the abnormality detecting means detects an abnormality in the motor control circuit and the detection signal is output to the stopping means, the stopping means turns off only the two switching elements. As a result, not only can all four switching elements be turned off, but also the stopping means can have a circuit structure that only turns off two switching elements, so that the number of parts can be reduced and the circuit structure can be simplified. I can do it.

According to a second aspect of the present invention, there is provided a control means for generating a current command value for assisting an electric motor of an electric power steering based on information signals such as a steering torque and a vehicle speed, and a control signal from the control means. Four switching elements connected in a bridge for turning on and off the drive current to the electric motor based on the following: an abnormality detection means provided in the control means for detecting an abnormality in the motor control circuit; and the abnormality detection When an abnormality detection signal is output from the means, a stopping means for turning off only two upstream switching elements connected to a power supply among the four switching elements is provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a motor control device according to the present invention will be described in detail with reference to the drawings.

In this embodiment, the present invention is applied to a device for controlling an electric motor (DC motor 11) of an electric power steering device. As shown in FIG. 1, detection is performed from a torque sensor 12 or a vehicle speed sensor (not shown). A main processor unit 13 and a sub-processor unit 14 each of which a built-in microcomputer calculates a current command value of an assist force based on an information signal such as the steering torque and the vehicle speed, and one of the processor units 13 and And an AND circuit 15 for inputting a control signal output from the DC / DC converter 14, and four switching transistor elements (MOSFETs) 16, 17, and 1 connected in a bridge for turning on and off a drive current for the DC motor 11.
8, 19, and the respective switching transistor elements 16 to
19 is provided with a power supply 21 for supplying a drive current via a relay circuit 20.

The main processor unit 13 and the sub processor unit 14 receive a relay drive signal from the relay circuit 20 by a relay drive circuit 22 and an AND circuit 2.
3 and the voltage difference between the upstream and downstream of the current detection resistor 24 is input via an operation amplifier 25. Further, both the processor units 13 and 14 are provided with abnormality detecting means for detecting an abnormality of the entire control circuit.

The current command value of the assist force calculated by each microcomputer of the main processor unit 13 and the sub-processor unit 14 is transmitted to each of the switching transistor elements 16 via four pre-drivers 26, 27, 28 and 29. To 19, and from here to the DC motor 11.

Further, downstream of the pre-drivers 26 and 27 on the two switching transistor elements 16 and 18 side, the two switching transistor elements 16 and 18 are turned on by a control signal (enable signal) from the AND circuit 15. Alternatively, the AND circuits 30, 3 for turning off
1 is connected. And the AND circuits 30, 3
1 is configured as a stopping means of the DC motor 11.

Hereinafter, the main processor unit 13
And the control of the DC motor 11 by the sub-processor unit 14 will be described with reference to the flowcharts of FIGS.

First, the control of the main processor unit 13 will be described. First, at step 1, it is determined whether or not the ignition key of the vehicle is turned on. Perform

Next, in step 3, the torsion bar torque is read based on the output signal from the torque sensor 12, and
Subsequently, in step 4, a necessary assist torque is calculated by calculation based on a detection signal such as a torsion bar torque.

Subsequently, in step 5, the target current value of the DC motor 11 is obtained by calculation, and in step 6, the current value of the DC motor 11 is read. In step 7, the voltage value of the DC motor 11 is calculated. In step 8, a voltage value is output to the DC motor 11 (PW
M output).

Next, in step 9, a signal from the abnormality detecting means is read, and in step 10, it is determined whether or not there is any abnormality. If it is determined that there is no abnormality, in step 11, it is further determined whether or not the ignition key is turned off. Is determined, and if it is determined that the switch is on, the process returns to step 3 to repeat the process. If it is determined that the switch is off, the process ends.

If it is determined in step 10 that the signal is abnormal, the process proceeds to step 12, where the enable signal is turned off to the AND circuit 15, that is, a prohibition signal is output. As a result, the two AND circuits 30 and 31 are turned off, and each pre-driver 2 is turned off.
The two switching transistor elements 16 and 18 are turned off via 6 and 27. As a result, the other two switching transistor elements 17 and 19 are not energized.

Subsequently, in step 13, it is determined by a timer whether or not a specified time has elapsed, and if it has elapsed, the process proceeds to step 14. Here, an off signal is output to the relay circuit 20, whereby the energization of the DC motor 11 is cut off and the rotation drive is stopped.

In step 15, it is determined whether or not the ignition key is turned off. If the ignition key is turned on, the process returns. If it is turned off, the process ends.

Next, control of the sub-processor unit 14 will be described with reference to FIG. 3. Basically, the same control as that of the main processor unit 13 is performed. That is, first,
At step 21, it is determined whether the ignition key is on or off. If the ignition key is on, the routine returns. If it is off, the initialization process is performed at step 22.

Subsequently, at step 23, the torsion bar torque is read, and at step 24, the current value of the DC motor 11 is read. Further, at step 25, a signal from the abnormality detecting means is read, and at step 26, it is determined whether there is any abnormality. Here, if it is determined that there is no abnormality, it is determined again in step 27 whether or not the ignition key is turned off. If the ignition key is turned off, the process ends. If it is turned on, the process returns to step 23.

If it is determined in step 26 that there is an abnormality, the process proceeds to step 28, in which the enable signal is turned off, that is, a prohibition signal is output.
1, both switching transistor elements 16, 18
Off.

Further, in step 29, it is determined whether or not this state has passed a specified time. If so, an off signal is output to the relay circuit 20 in step 30 to cut off the power supply to the DC motor 11. Control.

As described above, when an abnormality is detected in the control circuit, two switching transistor elements 16 and 18 are simply turned off instead of turning off all four switching elements as in the prior art. , Stopping means is provided for the two switching transistor elements 1
Since a circuit structure in which only the switches 6 and 18 are turned off is sufficient, the number of components can be reduced and the circuit structure can be simplified. As a result, the efficiency of the manufacturing operation can be improved and the cost can be reduced.

The motor control device of the present invention is not limited to the motor control of the electric power steering device of the present embodiment, but can be applied to the control of other motors. Further, the electric motor is not limited to the DC motor, but may be a polyphase motor.

[0030]

As is apparent from the above description, claim 1
According to the inventions described in (2) and (3), when the abnormality detection signal from the abnormality detection unit is output to the stop unit, the stop unit turns off only the two switching elements. This gives 4
As a matter of course, all of the two switching elements can be turned off, and the stopping means can have a simple circuit structure in which only the two switching elements are turned off, so that the number of parts can be reduced and the circuit structure can be simplified.

As a result, as a result, the efficiency of the manufacturing operation can be improved and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a motor control device of the present invention.

FIG. 2 is a control flowchart of a main processor unit provided in the embodiment.

FIG. 3 is a control flowchart of a sub-processor unit provided in the embodiment.

FIG. 4 is a block diagram of a conventional motor control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... DC motor 12 ... Torque sensor 13 ... Main processor unit 14 ... Sub-processor unit 15 ... AND circuit 16-19 ... Switching transistor element 21 ... Power supply 30 ... AND circuit 31 ... AND circuit

Claims (2)

[Claims] 1. An abnormality detection means for turning on and off a drive current for an electric motor to detect an abnormality in a motor control circuit, an abnormality detection means for detecting an abnormality in a motor control circuit, and an abnormality detection signal output from the abnormality detection means. When
A motor control device comprising: a stopping means for turning off only two upstream switching elements connected to a power supply among the four switching elements. 2. A control means for generating a current command value for assisting an electric motor of an electric power steering based on an information signal such as a steering torque or a vehicle speed; and a controller for controlling the electric motor based on a control signal from the control means. Four switching elements connected in a bridge shape for turning on and off the drive current; an abnormality detection means provided in the control means for detecting an abnormality in the motor control circuit; and an abnormality detection signal output from the abnormality detection means. When done,
A motor control device comprising: a stopping means for turning off only two upstream switching elements connected to a power supply among the four switching elements.