A Low Voltage High Power Bidirectional Multi-Port DC-DC Converter for DC Microgrids

Multi-port DC-DC converters (MPCs) are gaining attention in recent times as it can integrate more than one energy sources and energy storage devices into a single converter block. In this paper, a MPC topology is proposed for battery and supercapacitor-based hybrid energy storage system which is suitable for low voltage high power application in a DC Microgrid. The converter utilizes a three-phase current fed Dual Active Bridge (DAB) structure which provides galvanic isolation between the battery bank and the load. A low voltage high power supercapacitor bank is integrated at the load side by means of two stage conversion to achieve high voltage gain. The wide range zero voltage switching (ZVS) of the three-phase current fed DAB and bidirectional operation between any two ports are the key features of the proposed MPC. In addition, the input current ripple of both the storage devices are greatly reduced due to the interleaved structure. The operation of the proposed MPC and closed loop control strategy are discussed. A 20kW system is designed and simulated in the MATLAB Simulink environment to verify the proposed converter topology.