The co-phase power supply system can eliminate neutral sections and solve the problem of power quality. The isolated cascade converter realizes electrical decouple through isolated DC-DC converter, which can be widely used in the co-phase power supply systems. Canceling all of the isolated DC-DC converter can reduce the volume and cost. However, the large number of short-circuit paths decrease the available vector plane. In this paper, the influence of isolated DC-DC converter on the available vector boundary is analyzed. It is found that the partially isolated DC-DC converter of the power electronic transformer can be cancelled when the demand of the co-phase power supply system is satisfied. Therefore, a non-isolated and isolated hybrid power electronic transformer is proposed. The isolated module of the topology is located on both sides of the non-isolated module. The simulation and experiment result shows that compared with the three modules isolated cascade converter, the proposed topology can reduce two isolated DC-DC converters, and can increase the vector plane range by 142% compared with the non-isolated topology.

Co-phase power supply,Extended vector,non-isolated and isolated hybrid power electronic transformer,Short-circuit path