An airgap flux oriented vector controller for stable magnetic suspension during high torque acceleration in bearingless induction motors

A bearingless induction machine has the combined characteristics of an induction motor and magnetic bearings. It is known that the magnetic suspension of the rotor becomes unstable at over load operation, particularly in transient conditions. A novel airgap flux oriented vector control scheme has been proposed to operate the bearingless induction motor during the high torque acceleration period. It has been found that there is an optimal flux orientation for complete decoupling in radial force generation. Test results in a laboratory bearingless induction motor validates the performance efficacy of proposed controller at overload conditions.