Characteristics Investigation and Dynamic Test of Air-Cored Permanent Magnet Linear Synchronous Motor for null-flux PMEDS Vehicle

Potential of the null-flux permanent magnet electrodynamic suspension (PMEDS) had been delivered in terms of suspension and guidance. However, exploration of the propulsion system remains ambiguous, especially in analytical model and dynamic test. In this work, the electromagnetic characteristics of air-cored permanent magnet linear synchronous motors (PMLSM) are investigated, and a physical prototype equipped with complete measurement instruments are established and measured for the first time. Firstly, the structure and principle are introduced, followed by the tenable analytical model of air-cored PMLSM using the virtual displacement method. Additionally, the dependence of the exciting current, lateral gap and vertical offset on three-axis electromagnetic forces under two power angles are investigated through simulation and mathematical calculations. Finally, the complete measurement system, including positioning and speed system, a three-axis accelerometer, and auxiliaries, is constructed, along with the real-scale magnets. Linear dynamic tests are performed on the physical prototype, measuring and analyzing speed, displacement, and acceleration under varying exciting current and vertical offset. Results show that the analytical model enables fast and accurate calculations. In practical application, propulsion force decreases with vertical offset. Compared to current, the vertical offset possesses less contribution share of influencing propulsion performance. This work provides valuable insights for optimization design, coupled modelling and dynamic analysis, and test condition of null-flux electrodynamic suspension vehicle.