Multi-Port Arm Shared DC-DC Converter with Decoupling Control for Multi-Voltage DC Grid

Multi-port dc-dc converters are the core exchange hubs of dc grids, especially in new energy partition access and complex ring network scenarios. This paper proposes a multi-port arm shared dc-dc converter with flexible control of voltage and current at each port. For the multi-port architecture, a decoupling control strategy using node voltage control instead of the energy balance control between arms and a split-arm start-up method based on MMC ac/dc side active charging are proposed. The proposed control enhances the stability and robustness of the arm shared dc-dc converters under complex power variations at multiple ports. And the proposed start-up method reduces the difficulty of start-up implementation and has the advantages of low start-up stress and strong independence of each port. A prototype of a downscaled arm shared dc-dc converter with bipolar dual-LV-port structure, rated at 1.5 kW, ±240 V/±75 V, is built. The experimental results agree with the theoretical analyses and show that the proposed dc-dc converter with its control strategy and start-up method is very effective.