Cascade Sliding Mode Decoupling Control of Coupled Inductor Single-Input Dual-Output Buck Converter Based on Super-Twisting Extend State Observer

To address the coupling effect between the output branches of the coupled inductor single-input dual-output (CI-SIDO) Buck converter, which leads to the cross-influence and thus affects the dynamic performance of the system, a cascaded sliding mode decoupling control strategy based on the super-twisting extend state observer (ST-ESO) is proposed. First, a state-space averaging model of the CI-SIDO Buck converter is established. Then, the coupling terms, internal perturbations, and unmodeled parts in the inner and outer loops of the converter are estimated by using the ST-ESO with a fast-convergence property, which are regarded as the total perturbations in the inner and outer loops. Next, the total perturbation in the inner and outer loops is compensated by using a super-twisting sliding mode controller to achieve the decoupling of the system and ensure the robustness of the system and the stability of the output voltage. Furthermore, the stability of the super-twisting extend state observer and super-twisting sliding mode controller is analyzed using the Lyapunov theory, providing theoretical verification of the feasibility of the control strategy. Finally, the proposed control strategy is experimentally validated on the experimental platform. The results show that the proposed control strategy realizes the decoupling of the system, suppresses the cross-influence and improves the dynamic performance of the system.