Abnormal operation detection method and device for asynchronous motor

Abstract

The invention discloses an abnormal operation detection method and device for an asynchronous motor. The method comprises the following steps: acquiring stator currents and stator voltages of the motor; obtaining a reference motor output torque according to the stator currents and the stator voltages; acquiring a detected motor output torque; calculating the difference between the reference motoroutput torque and the detected motor output torque, so that a motor output torque deviation value is obtained; judging whether the motor output torque deviation value is larger than a preset thresholdor not; and when the motor output torque deviation value is equal to or larger than the preset threshold, outputting a motor failure signal. The method has the advantages that low-frequency operationof the motor, during which a forward defined rotation direction of an encoder is opposite to a forward defined rotation direction of the asynchronous motor, can be detected in time, so that within abearable failure operation range of the asynchronous motor, corresponding protection measures for the asynchronous motor can be taken in time to prevent greater failure effects further caused by an uncontrollable motor speed.

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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