Efficiency investigation of 2L-DAB and ML-DAB for high-power PV applications

This paper presents a comparison between efficiencies of the conventional two-level Dual-Active-Bridge (2L-DAB) and the Multi-Level Dual-Active-Bridge (ML-DAB) DC-DC converters for solar applications. A semiconductor chip-area-based comparison is employed to have a fair comparison between the two topologies. The definition of average efficiency for the European solar mix is utilized to make a comparison specific for a solar application. The rated power of the converters is 1 MW, and the switching frequency is swept from 10 kHz to 80 kHz to investigate its effect on the efficiencies of the converters. It has been shown that for a same amount of investment on the semiconductors, the 2L-DAB outperforms the ML-DAB both from efficiency and an operating junction temperature point of view. It has also been demonstrated that, by less than 70% more investment on the semiconductors, the efficiency of both converters can be increased by at least 0.7% while the operating junction temperature of the MOSFETs can be reduced by 50°C.