ABSTRACT
In an HTS bearing system, axisymmetric magnetic field of permanent magnet is locked by superconductor depending on flux pinning effect, and the movement in the axial direction will cause the change of the current and magnetic field states of the superconductor thus a levitation force would be generated. Radial HTS bearings are divided into two types: inner permanent magnet rotor type and outer permanent magnet rotor type. Rotation loss sources causing the rotation drag are not obvious. Efforts to identify and minimize the loss sources in HTS bearings were made in many research groups. Medium-scale category represents laboratory prototypes and engineering consideration of HTS bearings, and the bearing started to be used for the conceptual design of flywheel energy storage system. The research on the influence of superconducting materials on the rotation loss was carried out as early as the 1990s. The chapter provides preliminary information about rotational loss properties in the HTS bearings.
