A Partial Power Converter Interface for Battery Energy Storage Integration with a DC Microgrid

A battery energy storage system (BESS) interface for a DC microgrid, featuring a partial rated power electronic converter, is proposed in this work. Universal schemes for implementing a partial rated BESS interface are discussed and a soft-switched, dual active bridge (DAB) converter-based solution is presented. The proposed scheme is analyzed and compared with a conventional full rated BESS interface converter to showcase its benefits. A control strategy that can enable multiple operating modes for the the partial rated power electronic BESS interface is discussed. Hardware prototypes of partial rated and full rated BESS interface converter solutions that are rated to transfer 3.3 kW to the BESS are developed and tested in the laboratory. Experimental evidence suggests that the partial rated BESS interface can improve the system efficiency by up to 3% while simultaneously reducing the converter rating by about 70% as compared to that of a full rated converter. Elimination of redundant power processing by the partial rated BESS interface offers tremendous potential to improve the efficiency and power density while drastically reducing the cooling overhead.