Low Order Harmonic Reduction of Three Phase Multilevel Inverter

In this paper, a cascaded H-Bridge multilevel inverter has been proposed using unequal dc power sources and less number of switches. A standard cascaded multilevel inverter requires h number of de sources for (2h + 1) levels. This proposed scheme allows less number of unequal DC power sources without the requirement of transformers. Cascaded H-Bridge multilevel inverter fed induction motor shows the better performance due to fundamental frequency switching scheme. High quality output is derived due to the absence of lower order harmonics. High conversion efficiency is also achieved for induction motor drive when it is operated with the proposed inverter. The performance of three phase cascaded H-Bridge multilevel inverter with unequal dc sources is simulated by using MATLAB platform. Harmonic analysis is done on cascaded H-Bridge seven level inverter and experimental results are presented to demonstrate the superiority of the proposed system.