Simplified SHE pulse‐amplitude modulation for multilevel inverters

Abstract

In this study, a selective harmonic elimination (SHE)-pulse-amplitude modulation method is suggested for the cascaded multilevel inverters. This method is based on the balancing of the voltage-second area under the output voltage waveform and reference sinusoidal signal. The proposed method is free from the conventional transcendental SHE equations as it is based on a composite midpoint rule of numerical integration which works on linear equations. Reduced computational burden enables real-time implementation of the proposed method with great ease even for the inverter with a huge number of levels. The switching angles remain constant for an inverter while the output voltage is controlled by varying voltage of dc sources linearly. The proposed method eliminates more harmonics and offers reduced total harmonic distortion (THD) in comparison to the conventional SHE methods without amplifying the amplitude of higher order harmonics. THD of the output voltage remains constant with variation in modulation index. Performance analysis of the suggested method is validated with simulation and experimental studies on cascaded H-bridge inverter.