Second-order sliding mode controller design and its implementation for buck converters

A second-order sliding-mode (SOSM) control method is developed for the regulation problem of a DC-DC buck converter. By taking into account the model uncertainties and external disturbances in the mathematical model, a sliding variable with relative of degree 2 is first constructed. Then, a new SOSM controller is developed such that the output voltage will well track the desired reference voltage. Theoretical analysis shows that the resulting closed-loop system is globally finite-time stable, while similar SOSM control results only give the proof for finite-time convergence. The way on how to implement the proposed SOSM algorithm is also presented. The theoretical findings are verified by extensive simulations and experiments.