Robust Current-Limited Voltage Controller for Buck Converter Using Discrete Sliding Mode Design
This paper presents a robust voltage control of a buck converter with inductor current limitation applying discrete-time sliding mode control. The proposed voltage controller is designed in a hierarchical cascade structure comprising an inner current loop with current limiting and an outer voltage loop. Both loops employ sliding mode control in discrete time because of the achievement of finite-time dynamic performance. To ensure robustness against matched external and parametric disturbances, a disturbance estimation is introduced based on the integral of the sliding variable combined by an anti-windup mechanism to suppress overshoots. Including the current limiter ensures that the inductor current remains within safe operational boundaries, even during transient conditions, preventing hardware stress and enhancing reliability. The controller is implemented using pulse-width modulation (PWM) ensuring a fixed switching frequency and ease of practical implementation. The simulation results validate the proposed approach, demonstrating high performance, strong disturbance rejection, and negligible overshoot, while maintaining a straightforward and efficient control design.