Optimized Linear Motor for Urban Superconducting Magnetic Levitation Vehicles

The normal force that exists between primary and secondary of a linear motor plays an important role in Magnetically Levitated (MagLev) trains. In the particular case of the superconducting magnetic levitation (SML) method, based on the diamagnetic property of high-temperature superconductors (HTS) in the proximity of rare-earth permanent magnets, this issue is even more critical, as there is no control of the levitation gap, which changes according to the load. In this article, the previous experience of traction systems of MagLev trains in commercial operation serves as a background for the study and will be reviewed. The experience of other SML projects will also be considered to reach the proposed topology, similarly to the process of genetic evolution. The proposed solution for the normal force issue consists of a linear induction motor (LIM) optimized for an urban SML vehicle. Analytical equations and simulations with the finite element method (FEM) are presented. An innovative workbench for velocity tests was developed to measure the parameters of interest. Simulation and experimental results confirm the improved performance of the proposed LIM. The final results with the short primary LIM, designed and tested, showed excellent results. The LIM can be qualified as 3 times low: low-cost solution, for low-speed SML vehicles, and with low-normal force amplitudes.