Comparative evaluation of symmetrical and non-symmetrical bipolar SHE-PWM techniques

The well-known SHE-PWM techniques for the bipolar waveform are critically reviewed in this paper. Recent research contributions on this topic have reported optimization methods which are able of finding the multiple sets of solutions for any given number of switching angles. Moreover, the assumed symmetries used in the past to define the problem are not necessary and they can be abolished resulting in new sets of solutions and PWM schemes. The paper presents different formulations of the problem namely, quarter-, half-wave symmetry and non-symmetrical waveform. A critical evaluation/comparison between the three schemes is be reported based on various aspects such as, number of eliminated harmonics, harmonic spectrum profile, harmonic phasing, inverter performance, computational time, and solution space limitations. Selected simulation and experimentally validated results are presented to confirm the theoretical work of this study.