Sliding Mode Control For PMLSM Based On Singular Perturbation

Owing to the permanent magnet linear synchronous motor(PMLSM) possessing the trait of high response, high rigidity, high precision and etc, it has been subjected to apply to occasions of high speed, hypervelocity and precision machining and etc, and the study of the control strategy for PMLSM has been subjected to concern. The coupling between variables, parameter uncertainty, load disturbance and end effect consisting in the PMLSM servo system make precise control complex problem. The sliding mode controller containing flat sliding mode switching laws based on singular perturbation for PMLSM is designed based on embedded studying parameter perturbation, external disturbance and coupling relationship consisting in mechanical and electrical variables in the PMLSM servo system.For resolving the nonlinear variable coupling of the PMLSM, singular perturbation theory is dealt with coupling between velocity and current. To the problem of parameter uncertainty and external disturbance, the sliding mode control method is adopted, and the flat sliding mode switching laws is brought to PMLSM servo system to weaken buffeting phenomenon attributing to the sliding mode control.Owing to PMLSM servo system having characteristics of multiple time scales, the coupling between variables and nonlinear problem in PMLSM servo system is resolved by the sliding mode theory combining with the singular perturbation theory, complicated degree in course of design controller is reduced, and has high robustness for uncertain parameter perturbation and external disturbance. There are quasi steady state method and block diagonalizable method in singular perturbation theory, and the former resolves the system which time scale difference is small and the latter resolves the system which scale difference is big. First, the system is decomposed two different time scale subsystems by two methods respectively, then continuously differentiable sliding mode controller is used to design control laws for slow subsystem and fast subsystem, and two control laws of subsystems are combined the compound controller of PMLSM at last. Simulation results show that double sliding mode controllers containing flat sliding mode switching laws make PMLSM servo system possess fast dynamic response and the system has high robustness for parameter perturbation and external disturbance.