ABSTRACT
The unique operating features of active magnetic bearings are explained, including their fundamental feedback control functioning, including (1) the role of real-time rotor motion sensors, (2) the role of A-to-D and D-to-A digital signal converters, and (3) the intervening digital processer. The unique programmable operating characteristics of magnetic bearings are delineated and most importantly include the control of (1) bearing rotor dynamic stiffness and damping characteristics, and (2) prevention of rotor unbalance generated dynamic force transmission to the non-rotating part of the machine. The shortcomings of magnetic bearings delineated are (1) the lack of substantial momentary overload capacity, (2) the need for backup fall-down secondary bearings in case of an interruption of electric power to the bearing, and (3) the relatively high monetary cost of magnetic bearings.
