Super-twisting sliding-mode active disturbance rejection control strategy for LLC resonant converters
Abstract
To improve the dynamic response and disturbance rejection of the LLC resonant converter, a super-twisting sliding-mode linear active disturbance rejection control (STSM-LADRC) strategy is proposed. First, a small-signal model of the LLC resonant converter is established using the extended describing function method, and the converter transfer function is derived through model-order reduction. Then, a super-twisting extended state observer is designed to accelerate the estimation and compensation of lumped disturbances. By combining finite-time stability theory with input-to-state stability analysis, the proposed observer is proven to ensure the stability of the estimation error system and to achieve fast convergence. In addition, a STSM control law is introduced to replace the proportional-derivative control law in LADRC, thereby enhancing the dynamic regulation capability of the system. Its stability is also established based on finite-time stability theory. Finally, an experimental platform is built, and simulations are conducted to compare the proposed STSM-LADRC strategy with conventional LADRC and proportional-integral (PI) control. The experimental and simulation results demonstrate that, compared with PI and LADRC, the proposed STSM-LADRC strategy achieves superior dynamic performance and stronger disturbance rejection capability.