Investigation about SHM-PAM procedure for grid connected CHB seven level inverters

Abstract

This paper considers single phase cascaded H-bridges seven level inverters and proposes a pulse amplitude modulation procedure operating at fundamental frequency that mitigates many harmonics from its output voltage waveform, allowing to obtain low total harmonic distortion. The procedure fixes three switching angles and defines the values of the dc source voltages depending on them. Switching angles and total harmonic distortion are constant with modulation index m that can be changed by varying dc voltage sources that depend linearly on m. An investigation about results obtained by different switching angles choices is presented. Comparisons between simulated and experimental results are shown in order to highlight the accuracy of the proposed procedure.