Asymmetric Cascaded DC Sources Multilevel Inverter with Less Active Switches and Simpler Control Strategy

Abstract

Cascaded H-Bridge (CHB) multilevel inverter (MLI) is among the most preferred topology in solar PV systems. While traditional asymmetric CHB MLI is easy to achieve higher number of output voltage levels compared to traditional symmetric CHB MLI, charge balancing between the voltage sources remains a challenge for asymmetric CHB MLI. This drawback results in unsteady DC voltage levels due to unbalanced power drawn from each voltage sources. Besides that, in battery powered applications, unbalanced power drawn results in unequal discharged among the batteries. In this paper, an asymmetric half H-bridge (HHB) MLI topology is presented which is easy to modularize as for symmetric CHB MLI while maintaining the ease in charge balancing control. The performance of this proposed asymmetric HHB MLI with charge balance control has been evaluated using PSIM software.