Unfolded Resonant Converter with Large Conversion Ratio

Abstract:
A novel isolated resonant converter architecture is presented, featuring a two-phase series input on the primary side and a single current doubler rectifier in the secondary side. This configuration is intended to achieve a large step-down voltage conversion ratio as each phase is supplied by half of the highvoltage DC bus. The output transformer couples both phases, enabling the phase-shift control of the output current and maintaining a constant switching frequency. Given its superior performance for high current applications, a current doubler rectifier is chosen as the output rectifier. The circuit is inherently designed for short-circuit protection due to its voltage-controlled-current-source nature. The proposal is validated through a battery charger application with a step-down conversion ratio of 800-to-48 V.