Chattering free sliding mode control based on reduce order extended state observer method for a DC-DC Buck converter system

A novel chattering free sliding mode control (SMC) based on a reduced-order extended state observer (RESO) is proposed for a pulse width modulation based DC-DC buck converter with total disturbances and chattering. First, a novel tracking error state space model is introduced to define the matched and mismatched disturbances as a uniform matched disturbance. Second, a RESO is designed to improve estimation rapidity of tracking error differentiation and system disturbances. Moreover, the influence of load mutation, input voltage variation and system parameter uncertainties can further be attenuated by RESO via a feedforward channel. Third, an estimation of tracking error differentiation based sliding mode controller is designed to attenuate the disturbance estimation error, since the rapidity and accuracy of the buck converter voltage tracking can be improved due to achievement of the chattering free by defining the switching gain of sliding mode controller as zero. In addition, Lyapnuov stability criterion is developed to prove the stability of the proposed closed-loop controller. Finally, the simulation results show that the proposed method can effectively improve the robustness and dynamic performance of Buck converter by attenuating the chattering and total disturbances. © 2021, Editorial Department of Control Theory & Applications South China University of Technology. All right reserved.