Optimal Control of Three-level Dual Active Bridge DC-DC Converter Under Dual Phase-shifted Modulation

Three-level dual active bridge DC-DC converter is more suitable for high power and large capacity applications. Similar to traditional two-level dual active bridge DC-DC converter, its efficiency could be improved through soft-switching and little backflow power. In this paper, three-level neutral point clamped dual active bridge DC-DC converter under dual phase-shift modulation is analyzed. A modified control strategy is proposed to adjust phase-shift variables according to the rated power and bus voltages. Under this control strategy, the converter's operation could be optimized to achieve soft-switching and minimum backflow power. Finally, the feasibility of the proposed scheme is verified.