A Resonant DAB DC-DC Converter Using Dual Transformers With Wide Voltage Gain And Variable Switching Frequency

A series resonant dual active bridge DC-DC converter using dual transformers with variable switching frequency is proposed in order to be used in wide input and wide output voltage range applications. ZVS conditions for the switches are discussed in detail by using fundamental component analysis. The control trajectory of φ and D is designed to realize wide range ZVS for switches. Nominal operating point is designed to reduce circulating current by changing switching frequency. The design of the turn ratios and the resonant tank selection have been demonstrated. A 1-kW prototype was built to verify the effectiveness of the control strategy within wide voltage gain range. Besides, the switches can achieve wide range ZVS turn-on. The maximum conversion efficiency can reach 95.15%.