A new modulation strategy for improved DC bus utilization in hard and soft switched multilevel inverters

Multilevel inverters provide an attractive solution for high power, high voltage applications. While the multilevel topology permits higher voltages using devices of lower ratings, the DC link voltage balancing problem is a serious drawback which limits the applicability of multilevel topologies for motor drives. So far, redundant state selection has been the only method for regulating the capacitor voltages which results in a limited voltage capability. A new control strategy to improve the DC bus utilization, while generating low THD voltages is introduced. The proposed scheme is independent of the type of multilevel inverter topology and can be used for both hard and soft switching inverters. Simulation results are presented to demonstrate the validity of control scheme