Zero passage detection method and device of counter electromotive force of permanent magnet direct current brushless Hall motor

Abstract

The invention provides a zero passage detection method of counter electromotive force of a permanent magnet direct current brushless Hall motor, comprising the following steps of: applying PWM (Pulse Wavelength Modulation) voltage on two phases of three stator windings of the motor; detecting the voltage of a conducting phase and a non-conducting phase of the motor after the follow current of thePWM waveform during low level is finished; and judging whether the counter electromotive force passes zero or not by calculating the difference between two times of non-conducting voltage and the voltage of the conducting phase. The invention also provides a zero passage detection device of the counter electromotive force of the permanent magnet direct current brushless Hall motor. Since the detection is not carried out when the PWM waveform is high level, the filter and high-frequency noise can be avoided; and the invention has the advantages of favorable control performance, high precision,wide application range and low cost and is simple for realization in the whole detection process, can conveniently determine the position of a motor rotor in the operation process and realize the control of a brushless direct current motor without a Hall sensor.

Description

technical field [0001] The invention relates to the technical field of permanent magnet DC brushless Hallless motors, in particular, the invention relates to a zero-crossing detection method and a zero-crossing detection device for the counter electromotive force of a permanent magnet DC brushless Hallless motor. Background technique [0002] For the permanent magnet DC brushless Hallless motor, in order to commutate accurately during operation, the position of its rotor should be determined first. In order to determine the position of the rotor, the counter electromotive force zero-crossing detection method can be used. Some existing back EMF zero-crossing detection methods include: [0003] (1) The detection method of measuring the terminal voltage of the non-conducting phase of the motor to determine the zero crossing point of the counter electromotive force. However, it needs to obtain the mid-point voltage of the motor winding, the signal-to-noise ratio is low, and fi...

AI Technical Summary

Problems solved by technology

But this method is not suitable for motors with small armature inductance, the freewheeling time is too short, an external comparator is required, and the cost is too high

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