Comparisons of different three-stage three-phase cascaded modular topologies for Power Electronic Transformer

Power Electronic Transformer (PET) is one of the key elements for the future power electronics based power supply systems, especially in renewable energy field. In this paper, a series of new three-stage three-phase cascaded modular topologies comprising distinct AC-DC, DC-DC and DC-AC stages for large power rating PET are proposed. Comparisons of these topologies based on efficiency, cost, redundancy, control characteristics and supported functionalities, are performed. According to comparison, it has been concluded that one of these topologies is the most suitable one for large power rating PET.