Optimal programmed staircase waveforms for cascaded multilevel inverter

This paper presents four optimization methods for cascaded multilevel inverter to improve harmonic performance. There are several performance indexes that can be optimized such as distortion factor (DF), total harmonic distortion (THD) and efficiency. Minimization of THD is selected as an example here. These methods can generate better programmed staircase waveforms than conventional selected harmonic elimination (SHE) technique. The corresponding optimization algorithm and selection of starting points for calculating switching angles of each method are given in detail. Computational results show that the proposed methods have good convergence and effect.