PERFORMANCE ANALYSIS OF MULTI CARRIER BASED PULSE WIDTH MODULATED THREE PHASE CASCADED H - BRIDGE MULTILEVEL INVERTER

Abstract

A Multilevel inverter is a power electronic device built to synthesize a desired A.C voltage from several levels of DC voltages. Multilevel inverters have been an important development in recent years, owing to their capability to increase the voltage and power delivered to the motor with semiconductor switches which are available today. There are many methods available to control the cascaded multilevel inverter. In this paper, comparison of various multi carrier Sine Pulse Width Modulation (SPWM) control like Alternative Phase Opposition Disposition (APOD), Phase Opposition Disposition (POD), Phase disposition (PD), Phase shifted (PS) and Hybrid-carrier techniques in both uni polar and bipolar mode of three phase cascaded H-bridge 5- level inverter have been analyzed. Effective results have been demonstrated by simulation using mat lab 7.6.. Total harmonic distortion and distortion factor (DF) have been estimated for different modulation indices and the comparative results indicate that the cascaded multi level inverter triggered by the developed phase shifted SPWM strategy exhibits reduced total harmonic distortion. Hardware implementation has been carried out for the phase shifted SPWM strategy which has exhibited better performance