Comparative Study between Electromagnet and Permanent Magnet Rails for HTS Maglev

In this study, we investigated the magnetic levitation characteristics of a high-temperature superconducting (HTS) bulk with both permanent magnet guideway (PMG) and electromagnet guideway (EMG). Trying to have the magnetic fields of the two kinds of guideways with a similar structure, then the central magnetic flux density B-z and unit magnetomotive F-u were selected as the evaluation indexes respectively for the comparative study. Different magnetic field characteristics on magnetic levitation performance were studied, such as the gradient of magnetic flux density and magnetic flux density component in different directions. Several experiments were carried out at different magnetic field conditions by changing the exciting current of EMG or replacing different PMG specimens. The experiments were conducted with a high-precision force-measuring platform. The experimental results show that the EMG has several different characteristics as compared with PMG. As a result, the magnetic levitation performance is related to the gradient of magnetic flux density as well as the directional magnetic flux density components. The structure of the magnetic field also has great influence on the performance. The results will be helpful for further study of the properties of HTS maglev and provide guidance for the subsequent EMG design.