To address the difficulty of simultaneously achieving wide operating range and high efficiency in LLC resonant converters

as well as the poor dynamic performance and weak disturbance rejection associated with conventional controller-based loop design

an efficiency-optimized control strategy for hybrid-modulated LLC resonant converters is proposed. First

the gain and soft-switching characteristics of the converter under frequency and phase-shift control are analyzed

and a hybrid modulation control scheme is designed. Second

an improved self-disturbance rejection controller based on a low-pass filter is proposed to reduce measurement noise in the extended state observer and enhance the system’s disturbance rejection capability. Then

the losses of each component of the converter are analyzed to construct an efficiency optimization model

and an efficiency optimization method based on the mountain gazelle optimization algorithm is proposed to achieve efficiency maximization under hybrid modulation. By curve fitting of the optimal modulation parameters

the complexity of control loop design is reduced. Finally

an experimental platform is built to validate the theoretical analysis

and experimental results confirm the effectiveness and feasibility of the proposed efficiency optimization method and control strategy.