Unidirectional Active-Passive Bridge (APB) DC-DC Converter based on Resonant Control: FSM, PMW operation with Soft-switching range and Step Power Control Method

This paper presents a novel unidirectional high-frequency-isolated DC-DC converter called an Active-Passive Bridge (APB) DC-DC converter. The APB converter is composed of primary active H-bridge converter, high-frequency transformer, and secondary passive diode-bridge rectifier circuit. The feature of the circuit topology is a small resonant capacitor ($\text{C}_{\text{r}}$) connected to the each diode in parallel in secondary circuit. As the results, the APB converter achieves same trapezoidal waveform and control with Dual Active Bridge (DAB), high TPF (Total Power Factor), the dc conversion ratio and transformer utilization factor are highly improved. Output power is adjusted by FSM (Frequency Shift Modulation) or by PWM (Pulse Width Modulation) with soft switching range and Step Power Control Method is presented. The behavior and design of the proposed converter are explained, calculated and verified by experiments using 1 kW,20kHz laboratory prototype.