An active magnetic bearing with high T{sub c} superconducting coils and ferromagnetic cores

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:416739

Brown, G V; DiRusso, E; Provenza, A J ^[1]

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1. NASA Lewis Research Center, Cleveland, OH (United States)

A proof-of-feasibility demonstration showed that high-T{sub c}, superconductor (HTS) coils can be used in a high-load, active magnetic bearing in LN{sub 2}. A homopolar radial bearing with commercially wound HTS (Bi 2223) bias and control coils produced over 890 N (200 lb) radial load capacity (measured nonrotating) and supported a shaft to 14000 rpm. The goal was to show that HTS coils can operate stably with ferromagnetic cores in a feedback controlled system at a current density similar to that for Cu in LN{sub 2}. The bias coil, wound with nontwisted, multifilament HTS conductor, dissipated negligible power for its direct current. The control coils, wound with monofilament HTS sheathed in Ag, dissipated negligible power for direct current. AC losses increased rapidly with frequency and quadratically with AC amplitude. Above about 2 Hz, the effective resistance of the control coils exceeds that of the silver which is in electrical parallel with the oxide superconductor. These results show that twisted multifilament conductor is not needed for stable levitation but may be desired to reduce control power for sizable dynamic loads.

• OSTI ID: 416739
• Report Number(s): CONF-950722--
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
AC LOSSES
FEEDBACK
HIGH-TC SUPERCONDUCTORS
MAGNETIC BEARINGS
PERFORMANCE
SUPERCONDUCTING COILS