Digital implement of selective harmonic elimination based on digital signal processor

This paper proposes a digital implement method of selective harmonic elimination pulse width modulation (SHEPWM) based on digital signal processor (DSP). First, the switching angles for eliminating selective harmonics are calculated with computer-aided software, and functional relationships between modulation indexes and switching angles are obtained. The curve fitting technique is then used to fit the switching angle-modulation index curves, and fitting coefficients are stored in the memory of DSP. In vector control, the reference voltage is generated by the control loop. The modulation index is defined by its amplitude and switching angles are then calculated with the modulation index and fitting coefficients. By comparing the switching angles and the reference voltage phase angle, the PWM switching states are determined. Finally, experimental results are provided to verify the proposed method.