Comparison on unbalanced-load handling capability of two power electronic transformer topologies

Power electronic transformer (PET) has many merits as compared with traditional power transformer. In this paper, the unbalanced-load handling capability of two H-bridge based modular PET topologies, the separate-phase-connection (SPC) one and the cross-phase-connection (CPC) one, are analyzed. The two topologies consist of input stage, isolation stage and output stage. The related operating ranges for the two topologies are obtained if the system is confirmed. It finds that the former can deal with full-range unbalanced load if device current stress of the input-stage is increased to 115% while the latter is suitable for dealing with partial unbalanced-load conditions. From practical point of view, the former is more suitable for practical applications. Simulation results verify the analysis.