Model-assisted Active Disturbance Rejection Control of LLC Resonant Converter

When the load changes frequently, the main issues in LLC resonant converters with traditional controllers are large overshoot of the output voltage and long regulation time. To solve above issues, a model-assisted active disturbance rejection control(MADRC) is proposed. First, based on the extended describing function method, the small-signal model of the LLC resonant converter is established. Then, the transfer function of the LLC converter is obtained through order reduction. Next, the application of MADRC in the voltage loop of the LLC resonant converter is proposed, and the detailed design process of the MADRC controller is presented, and the Bode diagram of the system after compensation by PID controller, linear active disturbance rejection controller and model-assisted active disturbance rejection controller is compared. Finally, the operation and performance of the proposed control strategy are verified with a 300 W LLC resonant. Comparative experiments are conducted among PID controller, linear active disturbance rejection control(LADRC) and model-assisted active disturbance rejection control. The results demonstrate that the model-assisted active disturbance rejection control exhibits better performance in terms of fast response and robustness under load disturbances.