Fault tolerant active magnetic bearing electric system

DETAILED DESCRIPTION An object of the present invention is to provide a fault tolerant system for an active magnetic bearing, including a redundant electrical power system coupled to a switched reluctance generator such that the system is capable of supplying a multi-phase active magnetic bearing with power sufficient to maintain operation even in the presence of faulted phases or phase power supplies.
In an illustrated embodiment, the invention employs a power distribution system coupling a switched reluctance generator to a multiple axis fault tolerant radial magnetic bearing.
In an illustrative form, the bearing has three radial control axes which are made up of twelve electromagnetic stator poles organized into six electromagnets or force-producing pole pairs with 60.
degree.
radial spacing.
Two pole pairs at 180.
degree.
radial separation combine to generate a single control axis.
The stator core is segmented with nonmagnetic sections in order to minimize magnetic coupling between adjacent pole pairs .
This segmentation prevents interference between pole pairs under fault conditions.
Only two of the three control axes are required to maintain stable rotor suspension, with the third redundant axis providing fault tolerance.
The bearing electric system, including the controls for the electric system, the power supplies and the power electronic pole drives, are also independently operated from separate power sources to provide the additional fault tolerance for the electric power system.
In particular, the system is illustrated in an aircraft engine electric system employing active magnetic bearings for rotor suspension.
The system employs three independent direct current (DC) electrical distribution buses powered by an integral fault tolerant/redundant switched reluctance generator.
The three independent DC buses feed power to radial magnetic bearing structures having three control axes, one for each independent source of power.
The active magnetic bearings are configured such that each of the control axes is physically isolated and powered by a different DC power bus, respectively, such that failure of any given DC transmission bus results in a loss of force for that control axis only