Ambient-temperature passive magnetic bearings: Theory and design equations

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Research has been underway at the Lawrence Livermore National Laboratory to build a theoretical and experimental base for the design of ambient-temperature passive magnetic bearings for a variety of possible applications. in the approach taken the limitations imposed by Earnshaw`s theorem with respect to the stability of passive magnetic bearing systems employing axially symmetric permanent-magnet elements are overcome by employing special combinations of elements, as follows: Levitating and restoring forces are provided by combinations of permanent-magnet-excited elements chosen to provide positive stiffnesses (negative force derivatives) for selected displacements (i.e., those involving translations or angular displacement of the axis of rotation). ... continued below

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16 p.

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Post, R.F. & Ryutov, D.D. December 30, 1997.

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Description

Research has been underway at the Lawrence Livermore National Laboratory to build a theoretical and experimental base for the design of ambient-temperature passive magnetic bearings for a variety of possible applications. in the approach taken the limitations imposed by Earnshaw`s theorem with respect to the stability of passive magnetic bearing systems employing axially symmetric permanent-magnet elements are overcome by employing special combinations of elements, as follows: Levitating and restoring forces are provided by combinations of permanent-magnet-excited elements chosen to provide positive stiffnesses (negative force derivatives) for selected displacements (i.e., those involving translations or angular displacement of the axis of rotation). As dictated by Eamshaw`s theorem, any bearing system thus constructed will be statically unstable for at least one of the remaining possible displacements. Stabilization against this displacement is accomplished by using periodic arrays (`Halbach arrays`) of permanent magnets to induce currents in close-packed inductively loaded circuits, thereby producing negative force derivatives stabilizing the system while in rotation. Disengaging mechanical elements stabilize the system when at rest and when below a low critical speed. The paper discusses theory and equations needed for the design of such systems.

Physical Description

16 p.

Notes

OSTI as DE98057423

Other: FDE: PDF; PL:

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  • 6. international symposium on magnetic bearings, Cambridge, MA (United States), 5-7 Aug 1998

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  • Other: DE98057423
  • Report No.: UCRL-JC--129214
  • Report No.: CONF-980832--
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 302210
  • Archival Resource Key: ark:/67531/metadc675354

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • December 30, 1997

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  • July 25, 2015, 2:20 a.m.

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  • April 10, 2017, 2 p.m.

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Post, R.F. & Ryutov, D.D. Ambient-temperature passive magnetic bearings: Theory and design equations, article, December 30, 1997; California. (digital.library.unt.edu/ark:/67531/metadc675354/: accessed October 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.