Progress toward 500 kg HTS bearings

We have tested a heavy load HTS radial bearing dedicated for use in motors, generators, and flywheels. The HTS bearing is of radial type design providing both radial and axial support. The stator and rotor are modular assemblies which allows up-scaling in size. The superconducting stator is made of polycrystalline melt-textured (pmt) YBCO 200 mm inner diameter hollow cylinder grown in cylinder-like a-b texture. The stator assembly is composed of axially stacked YBCO rings in a Cu tube and cooled from the outside by LN₂. The rotor consists of stacked annular PM rings in compression on a shaft. This results in a high radial magnetic field gradient. Three such YBCO stators have been fabricated, assembled, and tested for use with a 380 kW superconducting motor developed by SIEMENS. Maximum radial forces of more than 3.7 kN were measured (at a temperature of 68 K) with the shaft at center radial position. The goal is to demonstrate safe operation of heavy rotors in a desired frequency range by providing sufficient forces, stiffness, and damping at critical modes.