A Single-Stage Dual-Active-Bridge AC-DC Converter Employing Mode Transition Based on Real-Time Calculation

In this article, a double degree-of-freedom variable control strategy with fixed frequency is proposed for a single-phase single-stage ac-dc rectifier based on dual active bridges. The proposed modulation strategy can achieve power factor correction without inner current ac current loop. In addition, the two control variables are calculated in real time without using look-up tables, and their combination not only achieves wider zero voltage switching range for switches but also lowers transformer current stress. The mode transition, the soft switching range, and working mode composition are analyzed. Besides, a 1-kW experimental prototype was built to verify the effectiveness of the control strategy.