Comparative analysis of level shifted PWM techniques for conventional and modified cascaded seven level inverter

Abstract

Researchers are attracted to multilevel inverters now days due to their better power quality and low total harmonic distortions as compared to bipolar inverters. In this work, study of total harmonic distortions of various level shifted PWM techniques such as In Phase Disposition, Phase Opposition Disposition and Alternate Phase Opposition Disposition PWM techniques on traditional and modified seven level inverter is done in MATLAB/SIMULINK environment. Also it has been observed that traditional seven level inverter utilizes twelve switches, whereas, modified topology only uses six switches. Hence, modified topology is suggested to better choice due to less number of switches, reduced switching complexity and cost of the system. The study of total harmonic distortions on various modulation index (m) for level shifted modulation is also done in detail.