Control Strategy of AC-DC Converter Based on Dual Active Bridge With Minimum Current Stress and Soft Switching

This article presents a control strategy for the single-stage dual active bridge (DAB) ac-dc converters. To reduce the conduction loss and achieve zero voltage switching (ZVS), the global optimal working modes are reviewed. Based on the global optimal working modes, the input current of the DAB ac-dc converter is analyzed for the sinusoidal input voltage. The control algorithm of the DAB ac-dc converter is proposed to achieve the unit power factor with the minimum current stress and ZVS. The range of the working modes is analyzed to meet the wide load power. The working mode is varied with the line-frequency angle and load power, which guarantees that the DAB ac-dc converter works in the optimal working modes. The conduction loss in the converter with the variation of the series inductance and the turns ratio of the transformer is analyzed. The series inductance and the turns ratio of the transformer are designed to further improve the conduction loss. The proposed control strategy is applied to a 1 kW DAB ac-dc converter with 220 V/50 Hz input voltage and 200 V output voltage. The experimental results demonstrate the working mode, the soft switching performance, fast dynamic response, high efficiency, and high power quality.