Magnetic bearings using bulk superconductors as a field shaping material

Magnetic bearings have been studied that use bulk superconductors as a field shaping material and need only a steel component on the rotor side. Two bearing configurations are considered: the bulk magnet type and the mixed-/spl mu/ type. In both systems, stable levitation of the steel rotor has been demonstrated. Electromagnetic force measurements have shown that the mixed-/spl mu/ type has better vertical force characteristics and similar radial force characteristics to the bulk magnet type. Rotation tests have been also carried out, which indicate that eddy current loss in the steel rotor is dominant and a larger loss was observed in the mixed-/spl mu/ type.