Highly Efficient Bidirectional Current-Fed Resonant Converter Over a Wide Voltage Gain Range

In this article, we propose a current-fed bidirectional resonant converter that has minimal switching loss over a wide voltage gain range. The proposed bidirectional resonant converter employs a double current-fed structure at the low-voltage side and an active voltage doubler with a bidirectional switch at the high-voltage side.The converter operates as a pulsewidth-modulation (PWM) double current-fed resonant converter in the forward mode and a PWM half-bridge resonant converter in the backward mode. By incorporating a bidirectional switch across center nodes of the active voltage doubler, the converter achieves almost zero-voltage switching at the turn-off instant, thereby, incurring little switching loss at all active switches. The proposed topology exhibits a high conversion ratio with low transformer turns-ratio and a low current ripple at the low-voltage side. The operating principles and theoretical derivations of the converter are discussed in detail. The performance of the proposed bidirectional converter are verified using a prototype that has 48-72-V low voltage, 380-V high voltage, and 1-kW output power.