Design and Implementation of Dual Active Bridge DC-DC Resonant Converter with Dual Phase-Shift Controls for Wide Voltage Range Applications

Resonant converters have been widely used in high power systems, but it is a great challenge for applications with wide range input/output voltages. The dual active bridge (DAB) DC-DC resonant converter is adopted as the main topology in this paper. When it operates with pulse-frequency modulation, the secondary-side switches serve as synchronous rectifiers to improve the efficiency. When the voltage gain of the converter is lower, the phase-shift control is applied to the primary-side switches to attain lower voltage gain; when the voltage gain of the converter is higher, the phase-shift control is applied to the secondary-side switches to achieve higher voltage gain. Thus, the resonant converter can be applied in wider input/output voltage condition. In this paper, the operating principles of the converter operated under different input and output voltages are discussed first, and then the relationships between the voltage gain and the phase-shift angles are analyzed. Finally, a DAB DC-DC resonant converter with input voltage (V_in) 200 V ~ 600 V, output voltage (V_o) 24 V ~ 48 V, rated power 1 kW, and resonant frequency 100 kHz is implemented. The experimental results validated that the phase-shift control method for the resonant converter is applicable in wider range input/output range. The highest efficiency of the system is 94.6% with V_in =400 V and V_o =48 V under full load condition.