JPH0686448A - Servo motor drive - Google Patents

Abstract

PURPOSE:To stop the revolution of a servo motor instantaneously when abnormality is detected by generating the stop command signal of the servo motor in a servo motor drive regardless of a speed command signal to the drive when the drive detects abnormality and the servo motor is stopped. CONSTITUTION:When an abnormal signal 6 is input to an abnormal signal detector 5, the detector 5 controls a relay circuit 13, and a speed command to a speed-error amplifier circuit 11 is transmitted over the OV side. Consequently, the same as a state, in which a stop command is input to the amplifier circuit 11, is brought. Since a motor 1 is rotated at certain speed yet at that time, the amplifier circuit 11 outputs the maximum value of a deceleration command. As a result, maximum brake torque capable of being generated by the motor 1 and a driver 3 is generated, thus quickly stopping the motor 1 as much as possible. Accordingly, the overrun of the motor can be inhibited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a synchronous type AC servo motor used in machine tools, industrial robots and the like.

[0002]

2. Description of the Related Art The structure of a drive unit for a synchronous type AC servo motor is generally shown in FIG. Figure 3
In the figure, 1 is a synchronous type AC servo motor (hereinafter abbreviated as motor), and the motor is a drive device (hereinafter abbreviated as driver)
The rotation speed is controlled by. The driver receives two speed command signals to control the rotation speed. On the other hand, the rotation speed of the motor 1 is detected by the speed detection device 7 attached to the motor 1, and the movement of causing the motor 1 to always follow the speed command signal 2 by the control circuit 4 is compared with the speed command signal 2. Has been done.

However, various abnormal states may occur in the drive system. Overload, overspeed, speed detector abnormality, driver abnormal heat generation, etc. When such an abnormality occurs, the abnormal signal 6 is input to the abnormal signal detection circuit 5 of the driver, and the output of the abnormal signal detection circuit 5 is normally 9 of the dynamic braking brake (hereinafter abbreviated as dynamic brake) circuit. To stop the motor as soon as possible.

[0004]

If any abnormality occurs, unless the motor is stopped immediately, the device to be driven will be destroyed or, in the worst case, a personal injury will occur. Shorter is better, and the result is less motor overrun. Mechanical braking has a problem of response time.

In the above-mentioned conventional example, if an attempt is made to stop the motor by the dynamic brake after some abnormality is detected, the dynamic brake in principle causes the brake torque to depend on the rotational speed of the motor. In a region where the speed is relatively slow, that is, immediately before the stop, the brake torque force is weakened, resulting in continuous rotation of the motor, and it takes time to stop the motor, resulting in unnecessary overrun of the control target. FIG. 4 shows the brake torque generated by the motor during dynamic braking and the change in the rotational speed of the motor.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a servo motor drive device that immediately stops the rotation of a motor after an abnormality is detected.

[0007]

In order to achieve this object, the servo motor drive device of the present invention forms a conventional dynamic brake circuit to stop the motor when various abnormality detection signals are input to the driver. Instead of the method described above, a means is provided for generating another stop command signal inside the driver regardless of the speed command signal input to the driver.

A circuit configuration example will be described in detail with reference to FIG. 1 of the following embodiment.

[0009]

By making the speed command signal unconditionally a stop command signal (hereinafter, this state is referred to as speed command 0) inside the driver, the brake torque for stopping the motor is almost immediately before the motor stops. Since the maximum torque that can occur is continuously generated, the motor can be stopped in a shorter time than when the motor is stopped by the dynamic brake.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the configuration diagram shown in FIG.

1 is a servo motor, 2 is a speed command signal, 3
Is a driver. Driver 3 during normal normal rotation
The speed command signal 2 is input to the motor 1 and the motor 1 is rotating.
On the other hand, the speed of the motor 1 is fed back to the driver 3 by the speed detector 7 and constantly compared with the speed command signal 2 to instruct to accelerate if it is slower or to decelerate if it is faster.
Is a speed error amplifier circuit. The gain of the speed error amplifier circuit 11 is usually set to be very high.

Now, when some abnormality occurs, the abnormality signal detection circuit 5 controls the relay circuit 13 to input a speed command to the speed error amplifier circuit 11 to the 0V side. The speed command signal is 0V, that is, the stop command is input. At that time, since the motor is still rotating at a certain speed, the speed error amplifier circuit 11 outputs the maximum value of the deceleration command. Since this generates the maximum braking torque that can be generated by the motor 1 and the driver 3, the motor 1
Can be stopped as soon as possible.

[0013]

EFFECTS OF THE INVENTION According to the present invention, an emergency stop due to the occurrence of an abnormality at the time of driving a motor is maximized by dynamically setting a speed command to 0 from the dynamic brake, and the time from the occurrence of the abnormality to the stop of the motor is minimized. As a result, it is possible to suppress the overrun of the motor.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a servo motor drive device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a signal waveform of each part and time in one embodiment of the present invention.

FIG. 3 is a block diagram of a conventional servo motor and driver.

FIG. 4 is an explanatory diagram showing a time relationship between motor speed and generated torque during dynamic braking.

[Explanation of symbols]

 1 Motor 2 Speed Command Signal 3 Driver 4 Control Circuit in Driver 5 Abnormal Signal Detection Circuit 6 Abnormal Signal 7 Speed Detector 8 Speed Feedback Signal 9 Dynamic Brake Circuit 10 Power Control Circuit in Driver 11 Speed Error Amplifier Circuit 13 Relay Circuit

Claims (1)

[Claims] 1. A servo motor control system comprising a synchronous type AC servo motor and a drive device for the servo motor, wherein when the drive device detects an abnormality and stops the servo motor, A servo motor drive device for generating a stop command signal for the servo motor in the drive device regardless of a speed command signal.