Nonlinear cascade sliding mode control based on extended state observer method for a DC-DC buck converter: Design and hardware experimentation

A nonlinear cascade sliding mode control (NLCSMC) based on extended state observer method is developed for a DC-DC buck converter in the presence of matched disturbances and uncertainties in this paper. First, all the matched and mismatched disturbances in DC-DC buck converter have been defined as a uniformed matched disturbance, including load and input voltage variations. Second, extended state observer is used to estimate the state variables and disturbances of the system that cannot be obtained directly. Third, a novel nonlinear function-based cascade sliding mode control method is proposed to achieve better convergence and disturbance rejection ability. Subsequently, the detailed convergence analysis of the closed-loop system is derived based on Lyapunov tools. Finally, simulation and experimental results are carried out to illustrate the nonlinear cascade sliding mode control based on extended state observer method (nonlinear cascade sliding mode control - extended state observer) has better control performance than linear cascade sliding mode control based on extended state observer method.