Control of Permanent Magnet Linear Synchronous Motor Servo System Based on Periodic Learning Disturbance Observer

To solve the problem of periodic disturbance in repetitive motion tasks for permanent magnet linear synchronous motor (PMLSM) servo system, a novel periodic learning disturbance observer (PLDOB) was proposed. Firstly, the dynamic model of PMLSM with the uncertainties was established, and a lumped disturbance was estimated by the disturbance observer (DOB). It consists of parametric variation, unmodeled dynamics, friction force and force ripple; and then, it was updated for each time period by the periodic learning law. This scheme requires no mathematical models of disturbances and control laws of model parameters, and it was designed from the point of view of disturbances directly. Also, it is possible to compensate for disturbances above as well as below the bandwidth of the Q-filter of DOB. Finally, the system experimental results confirm that the proposed scheme is effective and feasible. The tracking and disturbance rejection performance of system are improved greatly. © 2018, Electrical Technology Press Co. Ltd. All right reserved.