A Constant Frequency Second Order Sliding Mode Controller for Buck Converter

Sliding mode control technique is one of the best methods to regulate the output voltage of a DC - DC converter. The conventional first order sliding mode controller regulates the output voltage to the desired value but is effected by chattering. Chattering can be reduced by generating continuous version of the discontinuous control signal in the boundary layer sliding mode controller but this method may cause steady state error. Without affecting the system performance chattering can be reduced by using second order sliding mode controller. In this paper, Super-Twisting Algorithm is used for the implementation of second order sliding mode controller. Generated continuous control signals are compared with a repetitive sequence to obtain constant frequency switching signals for the buck converter. Simulation results indicate that the super twisting second order sliding mode controller not only reduces the chattering but also ensures accurate and fast response as compared to that of the boundary layer controller.