A novel cascaded multilevel converter drive system with minimum number of separated DC sources

Abstract

This paper proposes a novel cascaded multilevel converter for induction motor drives. By using systematic analysis, a novel multilevel converter with minimum number of separated DC sources has been developed. This multilevel converter requires only 50% of the number of DC sources required in conventional five-level cascaded converters. In addition, the three-phase output voltages of this converter can be easily balanced because they are synthesized by using the same DC sources. The harmonic reduction method is proposed to eliminate both the 5th and 7th harmonic. Simulation results show that the proposed converter can drive an induction motor with satisfactory speed responses. Moreover, the proposed method is easily realized. As a result, it can be applied in high power drive systems.