Design method and efficiency analysis of a DAB converter for PV integration in DC grids

This paper discusses the design method of a three-phase dual active bridge dc-to-dc converter (3ph-DAB) to integrate large-scale PV plants into medium-voltage (MV) dc grids. The DAB is employed as the maximum power point (MPP) tracker either on the string level or plant level. The converter's operation area is defined by the MPPs of the PV panels that are influenced by the environmental conditions. To maximize the converter's efficiency, a design process for the dual active bridge converter is developed to cover the largest possible operating area with the soft-switching operation of the 3ph-DAB. The efficiency of different design parameters is estimated over the whole operation range. Finally, the efficiency of the semiconductor devices and the transformer is calculated and analyzed.