Modulation Index Sweep for Selective Harmonic Elimination Technique for a 27-Level Asymmetric Multilevel Converter

Abstract

This work presents a sweep for the modulation index in a 27-Level Asymmetric Multilevel Converter that uses the Selective Harmonic Elimination modulation technique. Different set of solutions are obtained and presented in order to define the value of the firing angles for the multilevel waveform as well as the value of the modulation index. The number of levels in the converter decreases when the modulation index is low, which are calculated in order to minimize the Total Harmonic Distortion of the resulting voltage waveform. The plot of the firing angles is presented and the instants where the number of level changes is also shown, this is necessary for future implementation. Different waveforms for modulation indexes are shown as results. The proposal is validated using software simulations in time and frequency domains. Keywords—27-Level Asymmetric Multilevel Converters, Selective Harmonic Elimination, Modulation Index.