Fixed-Time Sliding Mode Control for DC/DC Buck Converters With Mismatched Uncertainties

In this paper, the fixed-time control problem of DC-DC buck converter systems with mismatched disturbances is investigated. Firstly, the sliding mode fixed-time observers are constructed to estimate the matched and mismatched disturbances of the systems. Secondly, a novel segmented terminal sliding mode control (TSMC) variable considering the mismatched disturbance of the system is designed based on the observations. To improve the tracking performance, a new second-order fixed-time reaching law is proposed. Then, in order to make the DC-DC buck converter systems with mismatched disturbances achieve accurate control in a fixed-time independent of the initial state, a novel fixed-time nonsingular TSMC based on the fixed-time observers is proposed. Finally, comparative experiments are conducted to verify the effectiveness and practicality of the proposed control strategy.