A Generalized Three-Phase Multilevel Current Source Inverter with Carrier Phase-Shifted SPWM

A Generalized three-phase multilevel current source inverter (CSI) structure is proposed in this paper. The novel multilevel CSI topology consists of n modules of current-source, three-phase six-valve converters and 2(n-1) sharing-current inductors. These inductors divide the dc link current into n-l different current ratings, and these current ratings are used to make up of 2n+1 current levels at the output of the CSI. In this structure, the bulky transformers in the ac side of the conventional CSI are eliminated, and current equilibrium problem of sharing-current inductors can be solved by redundant switching combination states. The operation principle and control strategy of the five-level inverter are analyzed in detail. The implementation of carrier phase-shifted SPWM scheme is investigated for digital control of the novel multi-module CSI structure. Simulated and experimental results demonstrate the proposition.