Selective Harmonic Mitigation (SHM-PWM) and THD Minimization: Performance Comparison of Different Formulations

Selective harmonic mitigation (SHM-PWM) is a low switching frequency modulation technique commonly employed in medium voltage - high power multilevel converters to increase their efficiency. Several different formulations, based on multi-objective cost functions, have been published in the technical literature to implement SHM-PWM together with total harmonic distortion (THD) minimization. However, a comparison is required to determine which formulation is more effective to solve the problem. In this way, this paper provides a novel comparison based on a study of the formulation equations and a brute force analysis. The formulation parameters have been optimized to offer a fair comparison in the brute force analysis. With the aim of considering the effect on the convergence of search algorithm effectiveness, the formulations have also been compared considering the results provided by a hybrid meta-heuristic-numerical search algorithm. As a result, the advantages and disadvantages of every formulation, besides some rules to optimize their parameters, have been extracted.