Design of second order sliding mode and sliding mode algorithms: a practical insight to DC-DC buck converter

Abstract

This paper presents a simple and systematic approach to design second order sliding mode controller for buck converters. The second order sliding mode control U+0028 SOSMC U+0029 based on twisting algorithm has been implemented to control buck switch mode converter. The idea behind this strategy is to suppress chattering and maintain robustness and finite time convergence properties of the output voltage error to the equilibrium point under the load variations and parametric uncertainties. In addition, the influence of the twisting algorithm on the performance of closed-loop system is investigated and compared with other algorithms of first order sliding mode control such as adaptive sliding mode control U+0028 ASMC U+0029, nonsingular terminal sliding mode control U+0028 NTSMC U+0029. In comparative evaluation, the transient response of the output voltage with the step change in the load and the start-up response of the output voltage with the step change in the input voltage of buck converter were compared. Experimental results were obtained from a hardware setup constructed in laboratory. Finally, for all of the surveyed control methods, the theoretical considerations, numerical simulations, and experimental measurements from a laboratory prototype are compared for different operating points. It is shown that the proposed twisting method presents an improvement in steady state error and settling time of output voltage during load changes.