Coupled Resonant Inductor-Based Interleaved Two-Phase SCLLC Converter With Auto Current Sharing and Ripple Reduction

The passive current sharing methods with coupled inductors for multiphase LLC converters typically cannot achieve interleaving operation, leading to high current ripple. To solve this problem, a coupled resonant inductor (CRI)-based topology is proposed with auto current sharing and interleaved operation. The proposed CRI topology is based on the switched-capacitor LLC converter (SCLLC), where the resonant inductors are moved out of the resonant tank and then combined into a coupled inductor. The improved coupled inductor method allows interleaving operation, achieving excellent current ripple cancellation effect while realizing auto current sharing. Besides, the partial power processing capability inherited from SCLLC reduces the losses in the coupled inductor. A 300W experimental prototype demonstrate that the current sharing error is within 4% across the load range of 5~25A. Besides, the prototype achieves a 56% reduction in output current ripple compared to a non-coupled implementation. Finally, the proposed topology maintains excellent efficiency performance (>96%) across the load range (5~25A), with a peak efficiency up to 97.5%.