Parallel inductor multilevel current source inverter with energy‐recovery scheme for inductor currents balancing

Abstract

Current source inverters (CSIs) have increasingly become popular because of their inherent advantages over voltage source inverter. In a single phase system, the operation of multilevel current source inverter (MCSI) requires large and bulky DC link inductor and the employment of switching state redundancy to balance the inductor currents limit the advantages of MCSI. This study proposed a new configuration for parallel MCSI. The proposed energy-recovery scheme provides a major path to release its stored energy in order to balance the sharing inductor currents and introduces a novel single state switching technique for the generation of MCSI output current. In addition, a chopper circuit with smaller inductor size is employed to replace the large and bulky input DC link inductor. An integration of five-level MCSI and a chopper based DC-current source with energy recovery scheme circuits produce a five-level MCSI with a simple converter structure. The performance of the proposed MCSI is analysed through MATLAB and is verified by constructing a prototype. The results demonstrate that the proposed circuit with the balancing inductor current scheme significantly reduces the input DC link inductor size, eliminate the control complexity in balancing the inductor currents and has excellent sharing inductor current characteristics.