Control Designs for Low-Loss Active Magnetic Bearing: Theory and Implementation

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.

Department dc:contributor.department

Electrical and Computer Engineering

Grantor dc:publisher

Georgia Institute of Technology

Year dc:date.issued

2004

Author dc:creator

• Wilson, Brian Christopher David

Advisors dc:contributor.advisor

• Ferri, Bonnie H.
• Panagiotis, Tsiotras

Committee members dc:contributor.committeemember

• Habetler, Thomas
• Sadegh Nader
• Taylor David

• Generalized complementary flux condition
• Flux Bias, Nonlinear Control
• Flywheel battery
• Magneic bearings
• GCFC

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/1853/5228

OAI identifier oai:identifier

oai:repository.gatech.edu:1853/5228