A Single-Stage Semi Dual-Active-Bridge AC–DC Converter With Seamless Mode Transition and Wide Soft-Switching Range

In this article, a novel single-phase single-stage ac–dc converter based on semi dual-active-bridge dc–dc converter is proposed for unidirectional power flow applications. Dual-phase-shift (DPS) and single-phase-shift (SPS) modes are adopted individually according to their operation. Only two control variables, which are primary side phase shift and the phase shift between the two bridges, are used. The optimal voltage and current waveforms in different operation modes are analyzed. The detailed transition process between the DPS mode and SPS mode is given, and the mode transition is seamless. The proposed converter can achieve high power factor correction without an inner current tracking loop. In addition, the switches can achieve zero-voltage switching on within a wide operating range and the rectifier diode can obtain zero-current switching off. The power transfer capability, mode transition mechanism, soft-switching range, mode operation range, and parameter design are analyzed. Besides, a 1 kW experimental prototype is built to verify the effectiveness of the proposed control strategy.