LLC resonant DC/DC converter with current-driven synchronized voltage-doubler rectifier

This paper proposes a current driving scheme for synchronous rectifier (SR) in the LLC resonant converter with a voltage-doubler rectifier. The voltage-doubler rectifier has a simple-structure transformer which only needs one winding on the secondary side. The voltage stress across SRs is reduced to half of that in a center-tapped rectifier, which means SRs with smaller on resistance can be used. With one Current Transformer (CT), the proposed current-driven SR features simple and well performs. Most of the reflected current from the CT will be feed backed to the output so that the power loss is low. Due to the current balance in the two output capacitors of the voltage-doubler rectifier, the magnetic balance circuit for the CT is not required. A prototype with 300-400 V input and 16 V/5.6 A output is built to verify the theoretical analysis, and efficiency of the converter is up to 93.5% at 350 Vin and full load condition.