A dual-switch gain-enhanced step-up/step-down converter for fuel cell powertrain

To address the critical demand for matching the fuel cell stack output voltage with the vehicle DC-bus voltage in fuel cell vehicles (FCVs), this paper proposes a novel dual-switch gain-enhanced step-up/step-down converter (SUDC). The SUDC integrates a three-inductor structure with synchronized dual switches, and the synergy of its two inductors supports an ultra-wide input voltage range and realizes high voltage gain even under low duty cycle conditions. Meanwhile, the synchronous on/off control of the two switches not only simplifies the design of the control system but also minimizes input and output ripple. Additionally, the converter adopts a common-ground structure and provides positive output voltage that further optimizes its compatibility with the power systems of FCVs. This paper deeply analyzes the converter’s operating mechanism in continuous current mode (CCM), quantifies the voltage stress on switching and nonlinear components, and calculates the optimal inductance and capacitance parameters. The proposed converter effectively reduces system losses and improves conversion efficiency. A 300 W prototype was fabricated for validation. Experimental results show that the output voltage remains stable during input voltage fluctuations and load switching, and a maximum efficiency of 96.93 % is achieved under full-load conditions, verifying the correctness of the theoretical analysis and parameter design.