Super Twisting Algorithm Based Sliding Mode Controller for Buck Converter with Constant Power Load

Increasing DC distribution systems and the share of renewable energy sources in energy production allows the widespread use of multiple DC/DC converter systems. Cascade converter structure, which is frequently used in multi-converter systems, exhibits constant power load behavior. Constant power load leads to the instability effect on the open-loop system due to its negative incremental impedance. However, these systems can be stable as a closed-loop by using different control techniques. Compared to conventional control methods such as PI and PID, sliding-mode control, which is one of the non-linear control methods, is a robust stance against external disturbances. In this paper, a sliding-mode controller based on a super twisting algorithm has been designed for a DC/DC buck converter feeding constant power load. The super twisting algorithm is a technique added to the sliding mode controller to suppress the chattering effect. The proposed controller ensures the stability of the system during steady state as well as provides that the output voltage remains constant whenever there is an alteration in the input voltage or constant load power. Moreover, the chattering effect, which is the most important weakness of the sliding mode control, has been significantly reduced by means of developed controller. The performance of the proposed controller has been verified by performing simulations in a MATLAB/Simulink environment.