Influence of fluctuant external magnetic field on the lateral unrecoverable distance of HTS bulks

Abstract

High temperature superconducting (HTS) maglev has great potential for high-speed rail transportation due to its non-contact nature, simple structure, and environmental benefits. The lateral stability of the HTS bulk superconductor is crucial for the curve negotiation ability of maglev trains running at high speeds. The HTS bulk can provide guidance for the maglev train without active control due to its unique magnetic flux pinning property. However, when passing through curves, it can deviate from its original position due to centrifugal effects and may not fully return to its original position. This deviation, known as the unrecoverable distance (UD), is closely related to the guidance performance of the maglev system. In this paper, the lateral UD of the HTS bulk is analyzed through lateral round-trip guidance force experiments using a customized HTS maglev dynamic measurement platform (SCML-03) with a circular permanent magnet guideway (PMG). The guidance force under different rotational speeds of the PMG was tested to study the effect of the fluctuation frequency of the external magnetic field. The influence of maximum lateral displacement (MLD), field cooling height (FCH), and working height (WH) on the UD of the HTS bulk are also discussed. The results showed that the rotational speed of the PMG has little effect on the dynamic guidance performance. The UD can be reduced by lowering the FCH and raising the WH appropriately. Additionally, methods should be found to restrain the possible MLD of levitated vehicles. This experimental analysis shows the lateral recoverable performance of the HTS bulk and provides a reference for the future design of the HTS maglev train.