Comparative study on various bipolar hybrid carrier PWM strategies for three phase five level cascaded inverter

This work presents the comparison of hybrid carrier Pulse Width Modulation (PWM) techniques for the chosen three phase Cascaded Multi Level Inverter (CMLI). In this paper, a CMLI is controlled with Sinusoidal PWM technique with Alternative Phase Opposition and Disposition and Carrier Overlapping (APOD + CO), Alternative Phase Opposition and Disposition and Phase Shift (APOD + PS), Alternative Phase Opposition and Disposition and Variable Frequency (APOD + VF), CO + VF, CO + PS, Phase Disposition and Variable Frequency (PD + VF), PS + PD, PS + VF , APOD + PD and CO + PD and the variation of Total Harmonic Distortion (THD) in the outputs is observed for various modulation indices ma. Simulation is performed using MATLAB-SIMULINK. It is seen that sinusoidal reference with PS+PD provides output with relatively low distortion. CO+VF PWM strategy is found to perform better since it provides relatively higher fundamental RMS output voltage and relatively lower stress on the devices.