A Dual Active Bridge DC-DC Converter with an Active Capacitor

The phase shift control strategy cannot ensure the zero-voltage switching (ZVS) operation for a dual active bridge (DAB) DC-DC converter operating at a wide range of voltage ratio. This paper proposed a DAB converter topology based on a PWM controlled active capacitor. The mathematical model of the variable capacitance is built, and it can be regulated dynamically to ensure ZVS over the full range of power level. A 500W experimental prototype operating at 100 kHz is developed to demonstrate the proposed topology. The simulation and experimental results are compared with the DAB converter with conventional phase-shift control method and show that all power switches of the primary and secondary side converters realize ZVS and a maximum efficiency of 94.6% is achieved.