Dual Transformer-Based Current-Fed Bidirectional DC-DC Converter With Wide Operating Range

A dual transformer (DT)-based current-fed bidirectional dc/dc converter is proposed to achieve soft switching operation over wide input voltage, wide output range, and wide power range. Hybrid modulation is adopted to achieve the zero current switching (ZCS) turn off and nearly zero voltage switching (ZVS) turn on for low-voltage (LV) side switches and ZVS turn on for high-voltage (HV) side switches over wide operating range. The proposed hybrid modulation incorporates three control degrees of freedom, which allows the leakage current of high-frequency (HF) transformer to commutate at different slope and makes the primary side voltage to be five level. Three feasible operating modes are identified for the wide operating range. A laboratory converter prototype has been built. Experimental results are presented to validate the analysis and design.