In this paper, a novel adaptive continuous sliding mode (SM) control approach is proposed based on the robust stability analysis of buck converters with multi-disturbances. Instead of the traditional first-order SM methods, the twisting algorithm is adopted to realize the control continuity and further weaken their inherent chattering problem. By introducing the zero-crossing detection innovatively, the influence of the traditional twisting algorithm with fixed control gain led to the low precision is effectively eliminated, and the small region can be controlled due to the implementation of the adaptive time-varying control gain. In addition, the magnitude of the controller can be reduced to a minimal admissible level determined by the system stable conditions and the selection of optimization parameters. Furthermore, multiple model uncertainties and external disturbances are considered into the modeling of the buck converters and the proposed adaptive SM controllers to ensure the strong robustness of the whole system while suffering possible disturbances. Finally, comparative simulations and experiments are given to validate the effectiveness of the proposed adaptive control strategy.INDEX TERMS Adaptive continuous sliding mode control, buck converters, zero-crossing detection, multidisturbances, twisting sliding mode control.

In this paper, a novel adaptive second-order sliding mode (2-SM) control approach, based on online zero-crossing detection, was proposed to solve the problems of the chattering and fixed control gain for buck converters with multi-disturbances. In modeling, the possible parameter perturbations and external disturbances of the converter system were contained. Instead of the traditional first-order sliding mode (1-SM), the twisting algorithm with 2-SM was adopted for the controller design, which could overcome the chattering problem and realize control continuity. Meanwhile, a novel adaptive mechanism was introduced to replace the conventional fixed control gain by time-varying control gain, the idea of which is to calculate the number of the zero-crossing points of the sliding surface online. As a result, the control magnitude of the improved controller could be reduced to a minimal admissible level, and the steady error of the output voltage could converge to the expected value. Furthermore, the robust stability of the converter system with multi-disturbances wads investigated. Comparative simulations and experiments validated the advantages of this paper as offering better robustness and control performance.