Analysis of Cascaded H-Bridge Multilevel Inverter

The multilevel inverter concept improves the quality of inverter over classic two level inverter. The increasing number of output level reduces the THD, results improved power quality. Based on the comparative benefits of the popular multilevel inverters, Cascaded H-bridge (CHB) inverter is selected for the analysis purpose. In this paper, considering the ease of sinusoidal pulse width modulation (SPWM) control techniques, both phase shifted (PS-SPWM) and level shifted (LS-SPWM) are used for generating the pulses for the considered inverter. The CHB inverter topology is generally apply for moderate and high power applications. The detailed construction and operating states for single phase 5 level, 7 level and 9 level inverter are presented. The device counts are observed, which shows the complexity for higher levels. But the simulation results for the same carried in MATLAB software depicts the lower Total Harmonic Distortion (THD) for higher level inverter.