Filtering method for demagnetization and commutation of brushless motor

Abstract

The invention discloses a filtering method for degaussing and commutation of a brushless motor, which comprises the following steps of: interrupting sampling by a controller at a set time interval, and acquiring phase voltages of two conducting phases and a suspension phase of the brushless motor in real time in a PWM-ON (Pulse Width Modulation-ON) stage; and judging whether the suspension counter electromotive force meets a high-voltage preset condition or a first medium-voltage preset condition or a first solid-pressure preset condition or a low-voltage preset condition or a second medium-voltage preset condition or a second solid-pressure preset condition or not. According to the method, different preset conditions met by the counter electromotive force of the suspension phase are set in one electric commutation period, so that the degaussing point waveform corresponding to the rising trend or the falling trend of the counter electromotive force is filtered out, the error rate of zero-cross detection of the counter electromotive force of the suspension phase is further reduced, the commutation accuracy and the motor control performance are improved, and the reliability of the motor is improved. And normal operation of the motor is ensured.

Description

【Technical field】 [0001] The invention relates to the field of brushless and non-inductive motors, in particular to a filtering method for degaussing and phase commutation of the brushless motor. 【Background technique】 [0002] Brushless motor has the advantages of large starting torque, good speed regulation performance, high efficiency, strong overload capacity, stable performance, simple control structure, etc., and at the same time retains the excellent mechanical characteristics of ordinary motors. It has been used in more and more industries Wide range of applications, such as automobiles, tools, industrial industrial control, automation and aerospace, etc. [0003] When the brushless motor adopts the sensorless square wave drive control, it relies on the back electromotive force or phase voltage to obtain the rotor position information, and relies on the back electromotive force zero crossing to obtain the commutation information. When the brushless motor is working ...

AI Technical Summary

Problems solved by technology

When the brushless motor is working under load, due to the inductive characteristics of the stator winding, there is freewheeling electric energy in the suspended phase, resulting in degaussing phenomenon, especially under the condition of high power load, the degaussing phenomenon is particularly obvious, which is manifested as a sudden increase in the suspended opposite electromotive force waveform or Reduced, and the degaussing phenomenon will cause false detection of back electromotive force, bring false zero crossings, lead to errors in commutation information, affect motor control performance, and even stop abnormally

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