Solution trajectories for selective harmonic elimination pulse-width modulation for seven-level waveforms: analysis and implementation

A detailed analysis of a seven-level selective harmonic elimination pulse-width modulation method suitable for multilevel DC-AC converters is presented in this study. Solution trajectories that cover the normal range of modulation indices typical for the operation of multilevel inverters are documented. The properties and characteristics of these solutions with regard to the distribution of switching instants (angles) to the levels of the waveform are also reported. Selected simulation and experimental results are included for both steady state operation and under dynamic changes of the modulation index and the output frequency. The results confirm the effectiveness of the method.