Initial guessing generalized formula for selected harmonic elimination PWM technique for cascaded multilevel inverter

Abstract

This paper proposes an accurate generalized initial guessing formula for calculating the initial values of the switching angles for the Selected Harmonic Elimination Pulse Width Modulation (SHEPWM) technique. This PWM technique is suitable for high-voltage, high-power Multilevel Inverters (MLI) used in fixed frequency applications. This PWM technique offers more degrees of freedom for specifying the harmonics content in the inverter output voltage, without any physical changes into the traditional configuration of MLI. By using the proposed generalized formula for switching angles initial guessing, the exact optimal switching angles solution of the nonlinear set of system equations was insured with minimum computational burden. Real-time implementation of SHEPWM technique for controlling MLI output voltage could be easily achieved. Different operating points for 5 levels inverter are documented for three-phase system. Selected simulated results are presented to verify and to validate the proposed approach. © 2011 Praise Worthy Prize S.r.l. - All rights reserved.