Ambient-temperature passive magnetic bearings: Theory and design equations
Abstract
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.
- Authors:
- Publication Date:
- Research Org.:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Org.:
- USDOE Office of Financial Management and Controller, Washington, DC (United States)
- OSTI Identifier:
- 302210
- Report Number(s):
- UCRL-JC-129214; CONF-980832-
ON: DE98057423; BR: YN0100000
- DOE Contract Number:
- W-7405-ENG-48
- Resource Type:
- Conference
- Resource Relation:
- Conference: 6. international symposium on magnetic bearings, Cambridge, MA (United States), 5-7 Aug 1998; Other Information: PBD: 30 Dec 1997
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; MAGNETIC BEARINGS; AMBIENT TEMPERATURE; PERMANENT MAGNETS; DESIGN
Citation Formats
Post, R F, and Ryutov, D D. Ambient-temperature passive magnetic bearings: Theory and design equations. United States: N. p., 1997.
Web.
Post, R F, & Ryutov, D D. Ambient-temperature passive magnetic bearings: Theory and design equations. United States.
Post, R F, and Ryutov, D D. 1997.
"Ambient-temperature passive magnetic bearings: Theory and design equations". United States. https://www.osti.gov/servlets/purl/302210.
@article{osti_302210,
title = {Ambient-temperature passive magnetic bearings: Theory and design equations},
author = {Post, R F and Ryutov, D D},
abstractNote = {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.},
doi = {},
url = {https://www.osti.gov/biblio/302210},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 30 00:00:00 EST 1997},
month = {Tue Dec 30 00:00:00 EST 1997}
}