Research of the voltage and current sharing issue of an H-bridge based power electronic transformer

Power Electronic Transformer (PET) is one of the most prospective components for future power electronics based power distribution systems. In this paper, the issue of the series-connected voltage sharing and the parallel-connected current sharing of a three-stage H-bridge based PET is discussed. Based on the present overall control strategy and application, it finds that the output-stage parallel-connected current sharing control serves to automatically achieve input-stage series-connected AC voltage sharing, however, the reverse does not work. In order to simplify the control strategy in the output stage, the output-current sharing control can be removed if the mismatch of the output filter inductors is within the range given by this paper. Simulation results verify the analysis.