High-Voltage-Gain Soft-Switching Converter Employing Bidirectional Switch for Fuel-Cell Vehicles

Abstract

Conventional current-fed resonant converter suffers from high turn-off loss over wide range of fuel-cell voltage. To alleviate this problem, we propose high voltage gain current-fed resonant converter that achieves almost ZVS turn-off over a wide range of voltage gain. By employing a bidirectional switch across center nodes of the voltage doubler and corresponding modulation, the presented converter achieved almost ZVS at the turn-off instant; this trait significantly increases the power conversion efficiency even under high frequency operation. The inherent boost function of the current doubler, an additional boosting operation using a bidirectional switch, and double boosting of the voltage doubler enable the presented converter to achieve high voltage gain without having to use a transformer that has a high turns-ratio. Moreover, 180 degrees phase interleaving reduces the input current ripple to zero. The steady-state operation is analyzed comprehensively, and design considerations of the proposed converter are given. Finally, a prototype with input of 48-72 V, output of 380 V, and rated power of 1 kW is developed to validate the effectiveness and feasibility of the proposed converter.