Direct displacement control of rotor eccentric for bearingless introduction motor

The bearingless induction motor has complicated electromagnetism relation, and is a multi-variable, nonlinear, and strong-coupled complicated system. There is strong coupling between the torque windings and radial suspension force windings, so the rotor radial eccentric displacement must be controlled accurately for realizing suspension of rotor steadily. In the control system, the torque windings are controlled by a versatile frequency converter, the sub-system of suspension force are controlled by displacement closed loop control. The relation expressions are deduced between radial suspension force and radial eccentric displacement, the control is designed, and the simulation is carried out. The simulation results show that the method can realize direct control of the rotor eccentric displacement, and the control has good dynamic and static performance.