Improvement of a magnetically levitated stepping motor using high T-c bulksuperconductor

A magnetically levitated stepping motor using high T-c superconductor has b een studied. The levitated stepping motor consists of a cylindrical rotor w ith superconductors and a stator with eight electromagnets. The rotor measu res 10 mm in diameter, 46 mm in length, and 18 g in mass. The superconducto rs of the rotor are field-cooled in liquid nitrogen. The levitated rotor is driven bp four-phase and eight-phase excitations. The rotation angles by e ach step are 90 and 45 deg, respectively. The rotor spins as the excitation phase shifts one by one. This paper discusses the dynamics of the motor dr iven by the four-phase and eight-phase excitations.