A Modular multilevel converter-based power electronic transformer

A Power Electronic Transformer (PET) performs the tasks of a conventional transformer by means of power electronic converters and medium-frequency transformers. A three-stage PET has high- and low-voltage AC and low-voltage DC output terminals. In this work, employing a Modular Multilevel Converter (MMC) at the first stage of a three-stage topology, a PET configuration is proposed, which not only has the common terminals, but also features a high-voltage DC terminal, enabling interfacing a DC distribution grid. Furthermore, the proposed configuration is readily scalable to high-voltage and power ratings. Besides, in the third stage of the proposed configuration, a simple two-leg inverter is used to supply a split-phase distribution system.