Improved Sliding Mode Active Disturbance Rejection Control for SIDO Buck Converter Based on High-Order Filtering Super-Twisting ESO

When a single-inductor dual-output (SIDO) Buck converter is disturbed by the load, a serious cross-coupling effect arises between branches, and the output signals are vulnerable to uncertain factors such as high-frequency measurement noise. To address the above issues, an improved sliding mode disturbance-observer-based control strategy based on a high-order filtering super-twisting extended state observer (HOFST-ESO) is proposed. First, the internal parameter influences and external disturbances are decoupled as lumped disturbances based on the mathematical model of the SIDO Buck converter to establish a disturbance-observer-based model without considering physical parameters. Next, a high-order filtering super-twisting extended state observer is designed to more accurately estimate and compensate for the lumped disturbances, enhancing the ability to suppress noise and cross-coupling effects. The stability of the observer is proven based on the finite-time stability theory. Then, an improved super-twisting sliding mode feedback control law is designed to ensure rapid convergence in both the sliding mode phase and the reaching phase, while better suppressing chattering. A Lyapunov function is constructed to analyze the stability of the feedback control law. Finally, the proposed control strategy is verified by simulations and experiments, which effectively reduces cross-coupling effects, suppresses noise, and improves the transient performance of the system.