PWM for Multilevel Inverter-State of Art and Comparison of its Various Techniques

Abstract

This paper suggests a comparison across various techniques of pulse width modulation (PWM) such as phase shift PWM (PSPWM), phase disposition PWM (PDPWM) and sine PWM (SPWM) applied across three phase cascaded HBridge inverter to yield seven level output in order to obtain a low distorted output waveform. Simulation has been carried out to analyse the comparison result in the form of waveforms and total harmonic distortion (THD) where it is found that that SPWM delivers lower THD and is reliable for the elimination of harmonics in the system comparatively.

Keywords: Multilevel Inverter (MLI), sine PWM (SPWM), Phase Dis-position (PD), Phase Shifted Carrier-based PWM (PSPWM)