A New Singularity Problem Solved Fast Terminal Sliding Surface with Fixed Switching Frequency for DC-DC Converters

Abstract

Compared to other control types, Sliding-Mode Control (SMC) offers a more unbounded design potential in addition to its high precision, simplicity, robustness, rapid response, and insensitivity to disturbances within a given range. Using the design freedom feature, this study proposes a novel fast terminal sliding surface, which is one of the new generation surfaces of SMC. By comparing the new surface with its counterparts in the literature, it has been shown with simulation data how effective it is in obtaining fast dynamic responses. Furthermore, the new sliding manifold solves the singularity problem associated with fast terminal sliding surfaces and this is detailed by theoretical analyses. From an experimental perspective, the suggested surface is tested on a step-down DC-DC converter. To ensure that the converter operates at a fixed switching frequency, parabolic modulation (PM), which is given as a novel approach in the literature and directly creates the switching signal, is utilized. To highlight the importance of PM, the system is also run with hysteresis modulation (HM). The system is subjected to a variety of disturbances, and dynamic results are obtained separately for both PM and HM. The relevant experimental outcomes show that the innovative surface successfully controlled the converter's state variable in both dynamic and steady-state conditions. Experimental results further reveal that the fixed switching frequency is obtained with the PM approach.