One-piece ring Nd-Fe-B permanent magnets and its performance for radial type superconductive magnetic bearing

摘要

One-piece ring Nd-Fe-B high performance permanent magnets are successfully produced for the radial type superconductive magnetic bearing (SMB) of 10 kWh class flywheel system. The inhomogeneity of magnetic flux density achieved is quite small and is less then +/-1% in the whole ring magnet with the size of OD 160.0 x ID 126.8 x 12.25 mm, where OD is outer diameter and ID is inner diameter. Levitation force density of 63,000 and 76,000 Pa was obtained for this SMB under 3 and 6 mm displacement at 77 K, respectively. Measured rotational loss was less than 0.14 W at zero initial load with 6000 rpm speed, which value is remarkably low compared with the previous data. (C) 2003 Elsevier B.V. All rights reserved. [References: None]