A MMC-Based Multiport Power Electronic Transformer With Shared Medium-Frequency Transformer

A modular multilevel converter (MMC)-based multiport power electronic transformer (PET) topology with shared medium-frequency transformer (MFT) is proposed in this brief, where the proposed PET is suitable for the hybrid AC/DC distribution network because of the existence of four essential voltage ports, including medium-voltage AC and DC ports, low-voltage AC and DC ports. Moreover, a multi-frequency modulation and the design of voltage decoupling circuit are introduced. One MFT is shared by three-phase MMC arms, which contributes to the compact structure and reduced cost of PET. The operating principle, applied control strategy and parameter design of proposed PET are introduced in detail. The experimental results are provided to verify the feasibility of PET.