Numerical Modeling of Iron Yoke Levitation Using the Pinning Effect of High-Temperature Superconductors

A ferromagnetic material can be levitated by the pinning effect of a field-cooled superconductor. This paper presents two methods for modeling this effect: 1) an approximate calculation to determine the relationship between attractive force and air gap at both room temperature and superconductive temperature (77 K) and 2) a novel way of modeling the pinning effect by a finite-element method (FEM). A comparison of analytical and FEM results with experimental results verifies the validity of the methods. The methods can be used to estimate the system´s behavior when the cylindrical yoke is replaced by a ring yoke. The stiffness of the system will increase by 70% (to 5.3 N/mm) when a ring yoke with the same surface area is used instead of a cylindrical yoke