Novel bidirectional snubberless naturally commutated soft-switching current-fed full-bridge isolated DC/DC converter for fuel cell vehicles

A novel naturally clamped zero-current commutated soft-switching bidirectional current-fed full-bridge isolated dc/dc converter is proposed. This proposed secondary-modulation technique naturally clamps the voltage across the primary-side devices with zero-current commutation, eliminating the necessity for active-clamp circuit or passive snubbers. Switching losses are reduced significantly owing to zero-current switching of primary-side devices and zero-voltage switching of secondary-side devices. Soft switching and voltage clamping are inherent and load independent. The voltage across primary-side devices is independent of duty cycle with varying input voltage and output power and clamped at rather low reflected output voltage, enabling the use of semiconductor devices of low voltage rating. These merits make the converter promising for fuel cell vehicles application, front-end dc/dc power conversion for fuel cell inverters, and energy storage. Steady-state operation, analysis, design, simulation results using PSIM 9.0.4, and experimental results are presented.