Vibration and Control of Flexible Rotor Supported by Magnetic Bearings

Many papers have been written on magnetic bearings. These papers are divided into two categories: One is the use of magnetic bearings taking the place of contact bearings, and the other is the use of noncontact actuators for active vibration control. These categories are combined in applications. The research on using magnetic bearings in place of contact bearings has been going on for years. As early as 1842 it was known that magnetic bearings should have at least one direction actively controlled [lJ. For the last century and a half there has been a great deal of research and development. Magnetic bearings have been used mainly in experiments and in aircraft and missile inertial guidance control. However, these bearings are now coming into use in the industrial world [2J for turbo-molecular pumps [3], machine tool spindles, etc. Although these magnetic bearings are for rigid rotors [4 to 6J, they recently have been used with flexible rotors [7 to 9J. In such applications. the magnetic bearings suppress unbalance vibration. Many papers have been published on this subject [10 to 16].