Modeling and Current Control Strategy for Independent-Coil-Based Permanent Magnet Linear Synchronous Motor

The independent-coil-based permanent magnet linear synchronous motor (ICPMLSM) has great flexibility due to the minimum unit control, and it plays an important role in advancing industrial automation. However, research on its modeling and current control is still limited. This paper presents a comprehensive study on both aspects. First, general linear models of inductance and back electromotive force (EMF) are established under different coupling conditions between the mover and the coils. Based on the principle of constant electromagnetic thrust, a current distribution strategy is developed, and a minimum-distance current switching strategy is further derived through the calculation of current zero-crossing points. Considering parameter variations under different coupling states, a model-free predictive current control (MFPCC) strategy is adopted to ensure robust current regulation. Furthermore, a model-free adaptive feedforward (AFF) controller is integrated into the MFPCC, forming an adaptive MFPCC (AMFPCC). This enhanced control scheme enables real-time compensation of both back EMF and resistive voltage through online parameter adaptation. Finally, the proposed control strategies are experimentally validated. The results confirm the effectiveness of the current distribution and switching methods, and demonstrate that the AMFPCC achieves near-zero steady-state current error while exhibiting strong robustness.