Fixed-Time Sliding Mode Control for DC-DC Converters with both Matched and Mismatched Disturbances Based on Disturbance Observer

In this paper, disturbance observer based fixed-time sliding mode controller is proposed for buck converter to ensure fixed-time stability and to eliminate the disadvantages caused by external disturbances or parameter/unmodelled uncertainties. The buck converter model, which incorporates both matched and mismatched disturbances, is initially described in order to create a comprehensive and accurate state-space model. A sliding mode observer predicting disturbances is developed and the sliding surface of the proposed controller is improved by adding the observer's disturbance estimate. Finally, a fixed-time sliding mode controller is designed independently of the initial conditions of the converter system. Lyapunov stability analysis is used to prove that the suggested technique achieves fixed-time convergence. Simulation studies prepared in Matlab/Simulink toolbox prove that the proposed technique exhibits superior dynamic performance compared to existing methods under various disturbance conditions.