Thrust Ripple Minimization of PMLSM Using Robust Two Degrees-of-Freedom controller and Thrust Ripple Observer

The permanent-magnet linear synchronous motor (PMLSM) has been widely applied in the servo control system. However, the thrust ripple and parameter mismatching inevitable exist in the PMLSM drive system, which reduces the tracking performance and stability. To improve the control performance of PMLSM, this paper proposes a hybrid control strategy by using a robust two-degree-of-freedom controller (RTDOFC) and thrust ripple observer (TROB). The designed RTDOFC is used to achieve preset dynamic response and satisfactory robustness to uncertain disturbance in current loop, and the constituent TROB is employed to suppress the thrust ripple by means of injecting the estimated value of thrust ripple to the reference current. Finally, the simulation is performed to validated the correctness and effectiveness of our method. The simulation results prove that the proposed control method can not only obtain strong robust performance to parameter mismatching, but also effectively suppress the thrust ripple.