Asymmetrical Bidirectional Converter for PV and EV Charging Systems Based on Solid-State Transformer

To meet the requirement for asymmetrical bidirectional power transfer in solid-state transformer(SST) applications, this paper proposes an Asymmetrical Bidirectional Active Bridge (AB2) DC-DC converter. On its secondary side, the converter employs a parallel connection of an active full-bridge and an uncontrolled rectifier bridge, significantly reducing the number of switching devices and thus lowering system cost. In forward mode, the converter operates as a dual half-bridge to enhance power-transfer capability; in reverse mode, it switches to a full-bridge configuration to accommodate lower-power flow. The proposed topology combines the advantages of reverse circulating power suppression and wide-range zero-voltageswitching (ZVS). Finally, a small prototype is built and experimentally tested, and the results validate the correctness and feasibility of the AB2 converter topology and the proposed modulation strategy.