Robust High Bandwidth Current Regulation for Permanent Magnet Synchronous Linear Motor Drivers by Using Two-Degree-of-Freedom Controller and Thrust Ripple Observer

Abstract

This paper proposes a high-performance current regulation scheme to enhance the current bandwidth and robustness of the permanent magnet synchronous linear motor (PMSLM). First, the disturbance caused by parameter variations and thrust ripple is considered in the modeling of PMSLM. Based on the model, a two-degree-of-freedom (2-DOF) controller consisting of improved predictive current control (PCC) and adaptive internal model control is derived. The improved PCC is used to overcome time delay and increase current control bandwidth, whilst the adaptive internal model is utilized to estimate the disturbance caused by parameter variations to compensate PCC. Second, a new discrete-time Jacobian linearization observer is designed to estimate the thrust ripple. The actual thrust ripple can be suppressed by injecting the estimated value into the control system. Subsequently, a comparatively smoother output thrust and higher precision position tracking is obtained. Finally, the precise test platform based on semiphysical system AD5435 is established. The experimental results verify the validity of the proposed approach.