Thrust Ripple Optimization of Double-Sided Permanent Magnet Linear Synchronous Motor Based on Specific Harmonic Elimination Technology

Double-sided permanent magnet linear synchronous motor (D-PMLSM) is widely used in precision linear motion systems due to its high power density, high thrust, and high precision. However, due to the end effect caused by end breaking and the non-sinusoidal air gap magnetic field, there is a problem of large thrust fluctuation. In this paper, the influence of the end effect on the air gap region is weakened by optimizing the primary length. Second, the expressions of mover magnetomotive force, stator magnetomotive force, and permanent magnet magnetization are derived, and the relationship between mover magnetomotive force and permanent magnet magnetization is pointed out. The source of thrust fluctuation is qualitatively derived and analyzed, and the harmonic number of the mover magnetomotive force corresponding to each harmonic of thrust fluctuation is obtained. By comparing with the finite element method calculation results, the number of thrust harmonics to be eliminated is determined, and the equations for eliminating the specific order of mover magnetomotive force are derived and iteratively calculated. Finally, the improved motor model is established according to the obtained modulation parameters, and the thrust performance is compared with the structure before modulation. The results show that the specific harmonic elimination technology can effectively eliminate the specific mover magnetomotive force harmonics, thereby eliminating the corresponding thrust harmonics, reducing the thrust ripple, and improving the stability of the motor operation. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.