Comprehensive Investigation on Harmonic Spreading Effects of SPWM and RPWM Methods

Abstract

Random pulse width modulation (RPWM) technique has emerged as a most used modulation strategy instead of sinusoidal pulse width modulation (SPWM) for the voltage source inverter (VSI) fed AC motor drives when the issues like acoustic noise, vibration etc. are the main concern. A comprehensive comparison of SPWM and Pseudo Random Binary Sequence (PRBS) bit based RPWM is presented in this paper. The distribution of harmonic power in the output voltage of VSI when controlled using SPWM is studied for three phase star connected resistive load. A MATLAB based organized comparative analysis of SPWM and RPWM methods characteristics such as total harmonic distortion (THD) in output line voltage, DC bus utilization and the harmonic spread factor (HSF) is presented.

Keywords: Harmonic spread factor (HSF), random pulse width modulation (RPWM), total harmonic distortion (THD)