To address the contradiction in traditional LLC resonant converters where a wide switching frequency range in wide voltage applications increases circulating current losses and leads to a decline in overall efficiency

an LLC resonant converter with a dual half-bridge three-channel topology is proposed. This converter employs a hybrid pulse width modulation-pulse frequency modulation (PWM-PFM) control strategy to establish three operating sub-modes: the synchronous dual-channel mode

the asynchronous three-channel bridge rectification mode

and the asynchronous three-channel voltage-doubler rectification mode. These sub-modes cover different gain ranges

enabling an ultra-wide output voltage range. The working principles under each mode and the derivation of gain formulas are analyzed in detail. Finally

an experimental prototype with an output voltage range of 15~150 V and a constant output current of 2 A is designed and built. Experimental results verify the feasibility and effec-tiveness of the proposed converter.