A study on combination of number of poles and slots of motor and number of magnetic bearing phase for uniform control of rotor

Abstract

By applying the halbach arrangement, an integrated magnetic bearing structure can be designed that secures the space inside the rotor core as a space for inserting the magnetic bearing. In this case, since the bearing is present inside the rotor, the bearing magnetic flux for controlling the rotor position is affected by the magnetic field of the permanent magnet and the rotating magnetic field of the phase winding of the stator. At this time, in a specific combination of the number of pole slots, the arrangement of the windings of the stator facing the bearing teeth appears asymmetrically for each bearing phase. In this paper, for more linear control, the formula for the number of stator pole slots and the number of bearing teeth to eliminate structurally generated force asymmetry was presented, and the formula was verified by comparative analysis of the force waveform for each axis. The validity of the proposed model was verified using the finite element method.