Method and device for detecting back EMF zero-crossing point of brushless DC motor

Abstract

The present invention proposes a back EMF zero-crossing point detection method and detection device for a brushless DC motor, wherein the method includes: after entering the back-emf zero-crossing point detection, obtaining the turn-on moment and turn-off moment of each PWM cycle in the PWM wave, Obtain the delay parameters of the terminal voltage sampling circuit, and determine the on-sampling interval and the off-sampling interval according to the turn-on time, turn-off time and the delay parameters of the terminal voltage sampling circuit; in the turn-on sampling interval, the terminal voltage of the floating phase winding is measured several times Sampling, and sampling the terminal voltage of the suspended phase winding multiple times in the off-sampling interval, so as to detect the zero-crossing point of the back EMF of the brushless DC motor when the terminal voltage is sampled each time. The back EMF zero-crossing point detection method of the embodiment of the present invention can accurately detect the back-emf zero-crossing point of the brushless DC motor when the motor speed is very high and the number of PWM waves is small, reducing the commutation error at high speed, And the cost is low.

Description

technical field [0001] The invention relates to the technical field of motor control, in particular to a detection method and a detection device for a counter electromotive force zero-crossing point of a brushless DC motor. Background technique [0002] Brushless DC motors are widely used because of their small size, high efficiency, and simple control. In order to reduce the hardware cost of the control system, a control scheme without a position sensor is mostly used, that is, the commutation is realized by detecting the zero-crossing point of the back EMF. The detection accuracy of the back EMF zero point directly determines the commutation accuracy of the brushless DC motor, thus affecting the control performance of the brushless DC motor. Especially in the high-speed brushless DC motor control system, the number of PWM waves in each commutation cycle is very small, resulting in fewer counter-EMF zero-crossing detection times and lower detection accuracy. Contents of ...

AI Technical Summary

Problems solved by technology

The detection accuracy of the back EMF zero point directly determines the accuracy of the commutation of the brushless DC motor, thus affecting the control performance of the brushless DC motor

Especially in the high-speed brushless DC motor control system, the number of PWM waves in each commutation cycle is very small, resulting in fewer counter-EMF zero-crossing detection times and lower detection accuracy.

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