Novel control strategy for robustness of two DOF Smith predictor via active disturbance rejection method

This paper presents a novel control strategy that employs a Smith predictor for large delay- time systems. Although the classic Smith predictor structure is superior for large delay-time compensation, it exhibits weaknesses when confronted with time varying disturbances, parameter uncertainties, and unmodeled dynamics. To overcome this intrinsic problem of the Smith predictor, this paper proposes a novel two degrees-of-freedom Smith predictor structure with two decoupled controllers. For fast reference tracking and robustness against disturbance, the reference controller is designed as a sliding mode controller and is developed using linear quadratic regulation and a modified smooth super-twisting algorithm. The perturbation rejection capability is enhanced by using an adaptive method and sliding mode based active disturbance rejection control. Thus, the developed control system can achieve robustness, accurate trajectory tracking, and fast response despite disturbances, noises, and mismatched errors. The simulation results demonstrate the effectiveness of the proposed control strategy in reducing the delay-time and system uncertainties, resulting in improved PMSM speed control.