Control Designs for Low-Loss Active Magnetic Bearings: Theory and Implementation
Brian C. D. Wilson
327 Pages
Directed by Dr. Panagiotis Tsiotras and Dr. Bonnie Heck-Ferri
Active Magnetic Bearings (AMB) have been proposed for use in Electromechanical Flywheel Batteries. In these devices, kinetic energy is stored in a magnetically levitated flywheel which spins in a vacuum. The AMB eliminates all mechanical losses, however, electrical loss, hich is proportional to the square of the
magnetic flux, is still significant. For fficient operation, the flux bias, which is typically introduced into the electromagnets
to improve the AMB stiffness, must be reduced, preferably to zero. This zero-bias (ZB) mode of operation cripples the classical control techniques which are customarily used and nonlinear control is required. As a compromise between AMB stiffness and efficiency, a new flux bias scheme is proposed called the
generalized complementary flux condition(gcfc). A flux-bias dependent trade-off exists between AMB stiffness, power consumption, and power loss. This work theoretically develops and
experimentally verifies new low-loss AMB control designs which employ the gcfc condition. Particular attention is paid to
the removal of the singularity present in the standard nonlinear control techniques when operating in ZB. Experimental verification
is conduced on a 6-DOF AMB reaction wheel. Practical aspects of the gcfc implementation such as flux measurement and flux-bias
implementation with voltage mode amplifiers using IR compensation are investigated. Comparisons are made between the gcfc bias technique and the standard constant-flux-sum (cfs) bias method. Under typical operating circumstances, theoretical analysis and experimental data show that the new gcfc bias scheme is more efficient in producing the control flux required for rotor stabilization than the ordinary cfs bias strategy.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/5228 |
| Date | 12 April 2004 |
| Creators | Wilson, Brian Christopher David |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
| Format | 10256524 bytes, application/pdf |
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