Protection method and device for alternating current permanent magnet synchronous motor

Abstract

The invention discloses a protection method and device for an alternating current permanent magnet synchronous motor. The method comprises the following steps of acquiring the stator current of the motor and the voltage of the motor; obtaining an estimation rotor magnetic field angle according to the stator current and voltage; obtaining a detection rotor magnetic field angle; acquiring a directional deviation angle according to the estimation rotor magnetic field angle and the detection rotor magnetic field angle; judging whether the directional deviation angle is larger than or equal to a preset deviation angle or not; and when the directional deviation angle is larger than the preset deviation angle, generating a control command for controlling the motor action protection, so that the motor operates according to the control command. According to the method provided by the invention, the directional deflection angle of the rotor of the motor is detected in real time, and the condition that the motor control system loses the control capability on the motor speed caused by the overlarge directional deflection angle can be avoided.

Description

technical field [0001] The invention relates to the technical field of motors, in particular to a protection method and device for an AC permanent magnet synchronous motor. Background technique [0002] In the vector control system of AC permanent magnet synchronous motor based on position encoder feedback, the field oriented control angle is obtained by adding the encoder bias angle to the current feedback angle of the encoder. When the encoder feedback is normal, the field oriented control effect It is greatly affected by the encoder offset angle. [0003] When there is a deviation in the field orientation, the real effective torque current under vector control is where θ err is the orientation deviation. If the orientation deviation angle is within ±90°, such as figure 1 As shown, the effective torque current is less than the control given value, the output torque of the motor is insufficient, the current is too large, and the motor heats up seriously; if the orienta...

AI Technical Summary

Problems solved by technology

Motor stall speeding is a serious control accident. On the one hand, excessive speed may cause damage to the mechanical system; on the other hand, due to the existence of the rotor permanent magnet, the back electromotive force generated by the motor stator increases with the increase of the speed. When the speed reaches a certain level, the motor feeds back energy to the control system. If the energy is too large, the control system will be damaged

Excessive directional control deviation will cause the control system to lose control over the motor speed, and the control system needs to detect this abnormality and take corresponding protection actions

The traditional control system only performs overspeed protection for the motor at high speed, and the protection signal is output only after the encoder feedback speed exceeds a maximum value, and the protection has a large hysteresis

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