Asymmetric multilevel hybrid inverter with reduced number of switches

Abstract

Multilevel Inverter is an array of power semiconductors and capacitors that allow the generation of a high quality load voltage. But it requires greater number of power semiconductor switches with increase in number of levels. In this paper, three phase hybrid topology of multilevel inverter is used to reduce the number of switching devices in the entire converter system. The proposed topology is a hybrid of cascaded H-bridge multilevel inverter (CHBMLI) and neutral point clamped inverter multilevel inverter (NPCMLI) so as to obtain seven level output in each phase. Third harmonic injection is adopted to increase the line to line voltage. Asymmetric dc bus voltage ratio is used to increase the number of levels. The main objective of this hybridised structure is to increase the number of levels with reduced number of switches.