RESEARCH ON THE SCHEME OF SENSING ROTOR POSITION OF BLDCM BASED ON THE THIRD HARMONIC COMPONENT
Zhang Zhong-chao · Proceedings of the CSEE · 2004
A novel method of sensing rotor shaft position of BLDCM (Permanent Magnet Brushless DC Motor) is presented based on the third harmonic component sensing. It is applicable to the BLDCM with trapezoidal back EMF waveform. Compared with the traditional back EMF, the third harmonic can be sensed even in a lower speed zone and only a small amount of low pass filter is needed. A digital phase locked up scheme is adopted in order to tracking on the 3rd harmonic precisely and quickly. A simulated phase voltage is sensed to help to verify the relationship between the 3rd harmonic wave and the rotor shaft position. The third harmonic sensing method is implemented in the laboratory based on a DSP 2407 control system. The experimental results shows the validity of the proposed method.