Bidirectional Modular Multilevel Resonant DC Converter for MVDC and LVDC Application

Medium-voltage (MV) high-power DC-DC converters are essential components in DC transmission and distributed generation systems, as they are responsible for matching different voltage levels and regulating power flow. This paper proposes a bidirectional modular multilevel resonant DC converter (BM-MRC). The operation principle and modulation scheme are introduced, and the control strategy by changing the switching frequency is further investigated to regulate the bidirectional power flow. Moreover, the submodules on the MV side can achieve zero voltage switching (ZVS), and the H-bridge on the low-voltage (LV) side can achieve zero current switching (ZCS) with the proposed control method. Finally, the proposed BMMRC and its control strategy are verified by simulation and experiment.