Switching sliding-mode control strategy based on multi-type restrictive condition for voltage control of buck converter in auxiliary energy source

In this paper, a switching sliding-mode control strategy is proposed for the voltage control of a buck converter in auxiliary energy source. The aim of this study is to solve the singularity problem of the terminal sliding-mode control strategy and simplify the implementation of the exponential operation of the non-singular terminal sliding-mode control strategy in practical applications. To achieve this goal, the state-space model of the buck converter in the auxiliary energy source is established. Furthermore, a novel switching sliding surface is defined based on the non-singular terminal sliding-mode control strategy. To ensure the stability of the switching sliding mode control system, a multi-type restrictive condition, including non-singular type and reachable type, is designed based on equivalent control law and Lyapunov stability criterion, respectively. Simulations and experiments are presented to verify the effectiveness of the proposed switching sliding-mode control strategy. The results show that both the non-singular terminal sliding-mode control and the switching sliding-mode control can effectively solve the singularity problem. Compared with the terminal sliding-mode control strategy, the non-singular terminal sliding-mode control and the switching sliding-mode control strategies have over 18% and 34.4% settling-time improvement of voltage adjustment to deal with the large load variation, respectively. The proposed switching sliding-mode control strategy can not only ensure the robust voltage control of the buck converter in the auxiliary energy source, but also simplify the implementation of exponential circuit in practical applications.