Enhanced four-port dual-active-bridge converter employing power decoupling capability for DC microgrid islanding mode operation

Abstract

Multiport DC-DC converters based on a dual-active-bridge (DAB) topology have attracted attention due to their high power density and bidirectional power transfer capability in DC microgrid systems. In addition, connectivity is high for various distributed resources (DRs). However, power coupling among ports magnetically connected by single or multiple transformers induces poor power control and voltage regulation performance. To mitigate these technical issues, an enhanced power decoupling method for a four-port DAB converter is proposed, which does not have supplementary power decoupling algorithms under the grid-connected mode and islanding mode operations of a DC microgrid system. In addition, a modular structure can be applied to individually connect a system with various loads. Finally, a 3-kW prototype four-port DAB converter is implemented to verify the validity and performance of the proposed method.