Impact of the number of angles and levels on harmonic mitigation in multilevel converters

This paper investigates about the impact of the number of levels and of the corresponding modulations angles on the mitigation of harmonics in cascaded H-bridge multilevel inverters. A mathematical model to reduce Nth odd harmonics from the output voltage of a multilevel converter is represented as a constrained optimization problem. It is further transformed in an unconstrained optimization problem that can be solved more simply by using the particle swarm optimization method. By varying the modulation index, the procedure guarantees the constancy of the output voltage amplitude.