Design of an Optimal Super Twisting Sliding Mode Controller for the Application of Voltage Control of a DC-DC Buck-Boost Converter

Abstract

DC-DC converters efficiently and quickly transform a direct input voltage to regulated direct output voltage. Control of DC-DC buck-boost converters is challenging because of the nonlinearity in its dynamics and complexities in the system. Proportional Integral Derivative (PID) controller is frequently used to obtain the required output voltage from converter due to its simplicity. However, using a PID controller for non-linear systems is neither dependable nor satisfying. In this thesis, Super-Twisting Sliding Mode Controller (STSMC) is designed for such converter system based on Genetic algorithms (GA) and Particle Swarm optimization (PSO) methods. To compare the designed controller, GA-based PID controller was designed. The study begins by formulating the mathematical model of buck-Boost converter and defining its control objectives. The STSMC is then designed and implemented using MATLAB/Simulink software package. The STSMC is a robust control technique that offers fast transient response and high disturbance rejection capabilities. it is capable of yielding the desired voltage under uncertainties due to variations in input load, voltage and also the reference. its performance is assessed by analysing its response characteristics, including settling time, overshoot, and robustness to disturbances. The simulation results demonstrate that the STSMC achieves excellent voltage control performance for the converter. In line with this, the PSO based STSMC has settling time for 0.3108msec, rise time for 0.19573msec and overshoot for 0.1402%. On the other hand, the PSO based STSMC for voltage control has improved performance than GA based STSMC and GA-PID controller. The proposed control systems are compared based on performance analysis. Additionally, under the influence of an external disturbance, the effectiveness of controllers is assessed. Finally, PSO based STSMC controller was acceptable rather than GA based STSMC and GA-PID controller for voltage control of the proposed system.