Performance Evaluation of Sliding Mode Control-Based DC-DC Buck Converter

Abstract

Robust voltage control in DC-DC buck converters is important in application of modern power electronics such power supply system, where systems are commonly open to parameter uncertainties and disturbances. Buck converter are used in applications were step-down voltage is needed. This converter alone typically produces an output voltage that is unstable, oscillates, has an enormous overshoot, and exhibit long time convergence. Several converters are needed to solve this issue and achieve a steady output voltage with quick fast response. PID controllers are typically used with converters to achieve nominal output voltage due to their ease of usage. PID controllers however are not reliable when used with nonlinear systems. To overcome these limitations, this thesis presents performance evaluation of SMC methods for buck converter. Its state-space average is modeled using continuous conduction mode (CCM) and linearized around operating point. The linearized model is expanded to include uncertainties in parameter and load change. SMC controller is built by defining appropriate sliding surface including proportional-integral action, with tuned parameter using particle swarm optimization (PSO) to improve transient response and minimize control chattering. System stability is analyzed using Lyapunov theory. Proposed control method is insured using simulations MATLAB/Simulink and compared with PID controller. Results show that SMC improves the rise time by 6.27% and the settling time by 7.19%, while eliminating desired voltage overshoot that remains with PID control (reduced to 3.65%). The improved SMC presented minimal chattering, with control input energy comparable to PID controller. Controller also maintains performance under 58% increases in load resistance and variations in inductance values. Overall, simulation results confirm SMC strategy greatly exceeds PID control methods, bringing better performance with efficient control, making it reliable and robust solution for high-performance buck converters.