The input voltage of the CLLLC resonant converter usually fluctuates with a certain magnitude

and such disturbances are easily transferred to the output

resulting in the increase of output voltage ripple

which in turn weakens the overall performance of the converter. To address the above issues

a composite control method based on linear active disturbance rejection control (LADRC) and fuzzy feedforward is proposed in this paper. By establishing the mathematical model of the CLLLC resonant converter

the voltage gain characteristics are analyzed

and the LADRC controller is designed to achieve the estimation and compensation of perturbation and effectively suppress the output voltage ripple. On the basis of considering the influences of output voltage and output power on voltage gain

the influence mechanism of input voltage change on the output voltage of CLLLC resonant converter is analyzed

and the feedforward compensation channel is constructed based on fuzzy logic controller (FLC). The feed-forward compensation channel dynamically adjusts the control signal according to the real-time changes of the fuzzy controller output and input side disturbance to achieve the feedforward compensation of the system. Simulation and experimental results show that the control method proposed in this paper can be adopted to significantly reduce the output voltage ripple and improve the stable operation performance of the system.