Robust nonlinear controller based on control Lyapunov function and terminal sliding mode for buck converter

Abstract

SummaryThis paper studies the sliding mode control (SMC) and terminal SMC (TSMC) techniques of output voltage regulation in dc–dc buck converters. In this paper, the conventional terminal sliding manifold (TSM), fast terminal sliding manifold, and adaptive terminal sliding manifold are investigated by using hysteresis‐modulated control. In addition, proportional‐integral‐derivative‐shaped TSM, PI‐shaped TSM, and proportional‐integral‐derivative‐integral‐shaped TSM are proposed in order to overcome the problems of conventional TSMs. Furthermore, a new continuous controller based on control Lyapunov function (CLF), with pre‐settable‐fixed switching frequency, is suggested. CLF‐based controller (CLF‐bC) is also adapted to the discontinuous digital input of the buck converter. In the proposed CLF‐bC, the switching frequency is completely independent and pre‐settable. Stabilization, reference tracking, high performance dynamic response, robustness against parameter uncertainties, and rejection of disturbances (e.g., input voltage changes and load variations) are some advantages of the proposed controllers. Impact of the controllers' parameters on the performance of the system is also summarized. Finite‐time stability of TSMs and proposed CLF‐bC, and the robustness of CLF‐bC against parameter variations and disturbances are mathematically proved. Performance of the proposed Adaptive TSMC (ATSMC), proportional‐integral‐derivative‐TSMC, and CLF‐bC has been verified through matlab simulations and compared with the conventional SMC and TSMC strategies. Copyright © 2016 John Wiley & Sons, Ltd.