Secondary-Side Phase-Shift-Controlled Dual-Transformer-Based Asymmetrical Dual-Bridge Converter With Wide Voltage Gain

Abstract

A novel dual-transformer-based asymmetrical dual-bridge (DT-ADB) converter with secondary-side phase-shift control strategy is proposed. The primary side of the DT-ADB converter is a fully active full bridge, and the secondary side is a semiactive bridge comprising of one active leg and two passive legs. The current and power of the two transformers in the converter are shared automatically by adopting primary-side-series and secondary-side-parallel configuration, and the turns ratio of the transformer is reduced by employing two transformers. The high-frequency-link inductor is reduced because the voltage applied on the inductor is reduced compared to previous converters, and hence the efficiency and power density can be improved. Zero-voltage turn-on of all the active switches and zero-current turn-off of all the diodes are achieved in a wide operation range. Furthermore, the turn-off losses of the secondary-side active switches are reduced because only half of the output current flows through the switches. Moreover, the proposed topology offers several other advantages including continuous output current and smaller output filter requirement. The operation principle is analyzed and experimental results are provided to verify the effectiveness and advantages of the proposed converter.