Force prediction and radial force compensation of a switched reluctance motor

Switched reluctance drives (SRM) generate significant radial magnetic forces in an eccentric motor shaft position. When the rotor is operating e.g. in its principal axis of inertia, these forces must be compensated by the bearings. This is of major interest for long term storage Flyweels where bearing efficiency is a key factor for the overall system performance. Force calculation by integration of the maxwell stress tensor is highly mesh dependent and analytical approaches have no satisfying accuracy. In this paper a method to predict forces due to eccentricity by the principle of virtual work in combination with the finite element method is presented. Furthermore a method to compensate radial forces will be demonstrated.