Electromagnetic Characteristics Analysis in Double-Sided Permanent Magnet Linear Synchronous Motor with Asymmetrical Air-Gap

The double-sided permanent magnet linear synchronous motor (DS-PMLSM) is widely used in the industrial field with high precision and long strokes due to simple construction, high instantaneous thrust and high controllability. However, parasitic issues, such as unavoidable manufacturing tolerances, might cause the symmetrical position deviation of primary or secondary components, which results in an asymmetrical air-gap between components, affecting the motor's electromagnetic characteristics further. In this paper, it is taken into account secondary torsional or offset conditions (the secondary component is displaced sideways from a symmetrical position), and investigates the variations of electromagnetic characteristics on the 12-solt 14-pole short-primary DS-PMLSM. Based on the finite element method (FEM), the effects of secondary torsion or offset on the air-gap flux density, the back-EMF, the detent force, the thrust force, and the normal force are investigated and compared respectively. In addition, the analytical results of the back-EMF considering lower secondary torsion are verified on a lower secondary torsional prototype. From the analytical results of electromagnetic characteristics, it is revealed that with the torsional angle or offset distance rising, the normal force and detent force in the Y-axis gradually increase, while the thrust force and the back-EMF decrease. These theoretical researches can play an important role in the operation and assembly process of the DS-PMLSM. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.