FUNDAMENTAL-STUDY ON HIGH T-C SUPERCONDUCTING MAGNETIC BEARINGS FOR FLYWHEEL SYSTEM

Basic quasi-static tests of the super conducting magnetic bearings are carried out using YBa2Cu3O7-alpha (hereafter mentioned as YBCO) and N d-Pe-B permanent magnet. In the thrust type tests two kinds of c-axis oriented YBCO bulks are used. These YBCO bulks are produced by a melt process using a seed crystal. The measured maximum repulsion pressure between the YBCO and the magnet between the YBCO and the magnet is 0.1 4 MPa at 77K under the zero-magnetic-field cooling condition. This rep ulsion pressure, which is a top level value, enables the authors to co nsider the application of the superconducting magnetic bearings. The a ttractive forces between the YBCO and the magnet under the field cooli ng condition are also measured at 77K. In the radial type tests the fo rce between a ring-shaped YBCO bulk and a shaft combined with multi-ri ng magnets are measured in the liquid nitrogen. A simplified formula i s proposed to evaluate the repulsion force. As an application of the s uperconducting magnetic bearings, a flywheel system is preliminary des igned for the energy storage of one kilowatt-hour. The flywheel, which is made of the fiber reinforced plastic, is a ring shape having an ou ter diameter of 600 mm and a height of 100 mm.