COMPARATIVE ANALYSIS OF SINUSOIDAL PWM STRATEGIES FOR THREE PHASE SYMMETRICAL CASCADED H-BRIDGE SEVENTEEN LEVEL INVERTER WITH REDUCTION OF SWITCHES

Abstract

This paper presents the comprehensive analysis of three phase symmetrical cascaded H-bridge (CHB) seventeen level inverter with reduced number of switches. Different bipolar Multicarrier level shifted Pulse Width Modulation (MCPWM) techniques such as Phase Disposition PWM (PDPWM), Carrier Overlapping PWM (COPWM) and Variable Frequency PWM (VFPWM) with sinusoidal reference are used to implement the proposed multilevel inverter (MLI) topology. The proposed MLI uses reduced number of switching devices thereby reducing losses and Total Harmonic Distortion (THD) compared to the conventional MLI topology. The time domain simulation of the proposed seventeen level inverter is carried out in Matlab/Simulink environment. The various performance factors such as %THD, VRMS, and VPEAK are calculated for two different modulation indices and the results are compared. The results demonstrate that the PDPWM technique provides relatively low %THD and the COPWM technique provides relatively higher fundamental RMS output voltages for the proposed seventeen level inverter having unity modulation index.