Efficiency-THD ratio in three-phase cascaded multilevel power converters of single DC source

This paper presents an experimental study of the relationship between performance and total harmonic distortion (THD) in cascaded H-bridges multilevel power converters. The aim of the study is to determine the existence of a relation between the decrease of the output voltage THD and the reduction of the converter performance. In the work, a three-phase H-bridge cascaded multilevel converter is implemented with nine stages per phase, using multiple PWM modulations with optimized harmonic content, which present different values of harmonic distortion. In this converter the performance and total harmonic distortion at the output voltage waveform for each of the modulations was analyzed and set the performance vs. THD.