Analysis of a low-normal-force coreless PMLSM for HTSP maglev propulsion system: finite element and analytical modeling

For high-speed operation of the high-temperature superconducting pinning (HTSP) maglev, adopting a coreless permanent magnet linear synchronous motor as the propulsion system ensures sufficient thrust while maintaining low normal force, thereby reducing the additional load imposed on the levitation system. In this study, based on the linear motor adopted in the HTSP maglev high-speed engineering prototype vehicle and test line, a three-dimensional finite element (FE) model is established to analyze the characteristics of the air-gap magnetic field distribution. The electromagnetic force of coreless and iron-core designs is compared. Subsequently, a two-dimensional analytical model is developed and further refined by incorporating the lateral end effect. Based on the three-dimensional magnetic field distribution obtained from the FE analysis, the analytical model is extended to a quasi-three-dimensional model. By comparing the analytical and FE models, the validity of the proposed analytical model is verified. On this basis, the influence of the air-gap length and the amplitude of the stator current on the electromagnetic force is investigated. The proposed analytical model is highly efficient in electromagnetic force calculation, providing a foundation for electromechanical coupling dynamics simulation of the levitation and propulsion systems in HTSP maglev.