In diverse applications

LLC resonant converters are widely used for high efficiency. However

traditional LLC topologies face an irreconcilable trade-off between switching frequency range and overall efficiency in wide-gain scenarios. To address this key issue

a three-channel LLC resonant converter with multi-mode switching was proposed via topology reconstruction. By controlling primary full-bridge/half-bridge switching and secondary bridge/voltage-doubler rectification

five operating modes covering five gain ranges were configured

enabling ultra-wide output voltage within a narrow frequency band. Efficiency is improved and cost is effectively reduced through switching device reuse. An experimental prototype(50-400 V output

400 W maximum power)was constructed to verify the proposed topology and control strategy. Experimental results confirm an 8x ultra-wide voltage gain range and smooth mode switching

demonstrating excellent performance and application potential.