Design and control of a four-port bipolar DC converter with dual-LC structure for MVAC-integrated microgrid applications

In emerging energy applications such as electric ships, smart buildings, and electric aircraft, power systems demand higher efficiency, voltage stability, and multi-source integration. This paper proposes a universal four-port voltage self-balancing converter suitable for ±800 V bipolar DC microgrids. The proposed converter integrates two Dual Active Bridge (DAB) modules and a dual-LC interleaved branch, achieving functional fusion of power coupling and voltage balancing via device-sharing techniques. A phase-shift control strategy is employed to independently regulate the three power transfer paths, enhancing system responsiveness under unbalanced power conditions. The converter is then integrated into a medium-voltage AC (MVAC)–bipolar DC (BPDC) hybrid power system, where a grid-tied inverter is modelled. Simulation studies under multiple disturbance scenarios confirm that the proposed converter effectively maintains bus voltage stability, suppresses current ripple, and improves power quality at the AC interface. These results demonstrate its practical applicability and val ue in next-generation hybrid microgrids.