Superconducting axial bearing for induction machines with active radial magnetic bearings

A superconducting passive axial bearing has been developed for an induction machine with vertical rotor and two active radial magnetic bearings, resul ting a fully levitating system. This prototype has been designed on the bas is of a previous one reported by Salazar-Stephan as 4-pole 2-phase inductio n machine using windings of a standard motor. Each active radial bearing me asures four shaft-positions using eddy-current sensors displaced each 90 de grees. The levitation has been performed using two NdFeB permanent magnets and bulk pieces of seeded-melt-textured YBCO. The YBCO pieces have been cha racterized measuring the levitation forces and mapping the remanent magneti c field with Hall probes. The radial stability of that system is modeled an d discussed.