Analysis of force harmonics and eddy current damping for 2 DOF moving magnet linear motor

This paper presents the analysis of force harmonics and eddy current damping for 2 DOF moving magnet linear motor (MMLM), which is utilized in magnetically levitated (maglev) positioning systems. A novel current-force model considering higher-order harmonics is proposed for MMLM in this paper, and this model provides an analytical tool to analyze the force ripple effect in MMLM theoretically. A commutation law is derived based on the proposed current-force model, which can ideally eliminate the force ripple in theory. In addition, the eddy current damping effect for a moving Halbach permanent magnet (PM) array on the conductive plate is analytically modeled in this work. By utilizing this model, the damping effect of MMLM can be derived using first principle. Finally, a prototype of MMLM is fabricated and experiment is conducted to implement the proposed commutation law and verify the eddy current damping model.