Bidirectional Hybrid-type Dual-Mode Isolated Resonant DC-DC Converter for Wide Voltage Range Application

A bidirectional hybrid-type dual-mode isolated resonant three-level DC-DC converter is proposed in this paper. The proposed topology integrates the advantages of both the full-bridge (FB) converter and the active neutral-point-clamped three-level (ANPC-3L) converter. Under the high output voltage application, the proposed converter operates in the three-level mode, offering the benefits such as the low voltage stress, balanced losses, reliable voltage clamping, and high efficiency. Under the low output voltage application, the proposed converter is reconfigured from ANPC-3L topology to the FB topology by reusing the power switches to reduce the current stress. Through the adaptive topology reconfiguration, the converter exhibits the advantages of the lower voltage and current stress and the high-efficiency operation under the wide voltage range. In addition, a switching logic is designed to enable the seamless singe-cycle-level four-step online transition between the two modes without shutdown. A 1 kW experimental prototype covering 200-800V is built and compared with the conventional ANPC-3L converter. Experimental results show that, under low-voltage conditions, the current stress of proposed converter is half of that in the ANPC-3L converter. And the mode-transition is safely completed within the single switching period. The effectiveness of the proposed converter and mode-transition strategy is validated.