Method and device for detecting abnormal operation of asynchronous motor

Abstract

The invention discloses a method and device for detecting abnormal operation of an asynchronous motor. The method includes: obtaining the stator current and voltage of the motor; obtaining the output torque of a reference motor according to the stator current and voltage; obtaining the output torque of the detected motor; calculating The difference between the output torque of the reference motor and the output torque of the detected motor is obtained to obtain a deviation value of the output torque of the motor; it is judged whether the deviation value of the output torque of the motor is greater than a preset threshold; when the deviation of the output torque of the motor When the value is greater than or equal to the preset threshold, a motor failure signal is output. Through this method, it is detected in time that the motor is running at a low speed frequency. At this time, the positive direction of the encoder defines the rotation direction and the positive direction of the asynchronous motor. Protective measures to prevent the motor speed out of control from further expanding the impact of the fault.

Description

technical field [0001] The present application relates to the field of motor technology, and in particular to a method and device for detecting abnormal operation of an asynchronous motor. Background technique [0002] The asynchronous motor current model based on the rotor field orientation is widely used in the asynchronous motor vector control device because the formula is simple and easy to calculate, and the required motor parameters are few. The current feedback frequency of the encoder plus the integral of the motor slip frequency required for control is calculated. This vector control device is called indirect field-oriented vector control. [0003] Whether the speed direction of the encoder feedback is opposite to the rotation direction of the asynchronous motor is determined by the physical relationship between the two when they are installed on the one hand, and is also related to the phase sequence of the output signal on the other hand. When the rotation direct...

AI Technical Summary

Problems solved by technology

When the rotation direction defined by the positive direction of the encoder is opposite to that of the asynchronous motor, the above-mentioned indirect field oriented vector control device is in a state of abnormal control, which is specifically reflected in the fact that the asynchronous motor runs at a lower frequency, and the motor speed cannot Run according to the speed command, the motor speed is out of control, and the output current is large at the same time. If there is no other detection and protection mechanism, this state will cause the motor to stop or run at a low speed, causing the motor to burn out.

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