High Power Density Bidirectional Three-Port DC-DC Converter for Battery Applications in DC Microgrids

DC microgrids, which have a variety of energy sources must need energy storage systems (ESS)to stabilize the grid systems. A triple active bridge (TAB)converter has advantages of galvanic isolation, bidirectional power transfer, and small quantity of components. However, the conventional TAB converter requires power decoupling control to remove power correlation between ports, which brings complexity in control manner. In addition, it induces circulating current in the ESS port even when it is not used, which decreases the total power conversion efficiency. This paper presents an isolated bidirectional three-port DC-DC converter that has high power density, absence of the power decoupling control and the low circulating current in the ESS port remaining at zero power. All the functionality and performance of the proposed converter are verified by PSIM simulation and experiments with a 5-kW prototype converter.