Multisurface HTS-PM Levitation for a Flywheel System

In this paper, a multisurface levitation concept using three permanent magnets (PMs) and one high temperature superconductor (HTS) ring in a levitation configuration is studied to improve stiffness in a superconducting magnetic bearing system. A geometrical rule is defined to select the size of second and third PMs placed over and under the ring HTS to overlap the frozen images of all PMs. For different combinations of the PMs, experiments are realized and levitation forces are measured. Three levitation surfaces case with attractive polarization of the PMs provided the largest levitation force in the experiments.