Short-circuit fault-tolerant control of bearingless permanent magnet slice machine

This paper investigates the controllability of a 6-phase single winding bearingless permanent magnet (PM) slice machine drive system under a variety of power electronic short-circuit conditions and the proper control algorithms to accomplish the successful rotor levitation under these short-circuit faults. Analysis shows that the bearingless PM slice machine drive system is only controllable under the following short-circuit fault conditions: 1) short circuit in one single phase winding, 2) short circuit in two adjacent phase windings, and 3) short circuit in two opposite phase windings. Experiments are performed for the above three short-circuit fault conditions to verify the proposed control algorithms.