Rotational accuracy of superconducting magnetic bearings

Analytical and experimental study of rotational accuracy of superconducting magnetic bearings depending on the arrangements of permanent magnets is presented in this paper. With the aim of improving the rotational accuracy, the axial bearing magnet ring was divided into two rings in the radial direction and the radial bearing magnet sleeve was divided into three stacked rings in the axial direction. As a result, the magnetic flux density could be increased at the superconductor ring position, the static stiffness and the load capacity were increased, and hysteresis became large. Concerning the dynamic characteristics, the rotational accuracy of the shaft was improved remarkably and the shaft weighing 2.4 kg could rotate within 15μm peak to peak at 12 000 rpm.