Three-Phase Asymmetric Multilevel Inverter Topologies with Better Charge Balancing

Abstract

Cascaded H-bridge multilevel inverter is among the most preferred topology in solar systems. While traditional asymmetric cascaded H-bridge multilevel inverter is easy to achieve higher number of output voltage levels compared to traditional symmetric cascaded H-bridge multilevel inverter, charge balancing between the voltage sources remains a challenge for asymmetric cascaded H-bridge multilevel inverter. 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 in the batteries. In this paper, two three-phase asymmetric cascaded H-bridge multilevel inverter topologies are proposed which offer easier in terms of modularity while maintaining the ease in charge balancing control. The performance of these two proposed topologies with charge balance control has been evaluated using PSIM software.