Performance verification of saturated IPM bearingless motors considering magnetic pull variation

Interior permanent magnet (IPM) bearingless motors are becoming a good choice for high-speed applications. In these motors, reducing the thickness of the PM leads to the increase of the radial forces which affects the demagnetizing fields. Various types of PM motors have so far been recommended for enhancement of the radial forces and torque. In the proposed IPM motor the d-axis flux-linkage and the q-axis torque component are raised due to the armature reaction and this saturates the stator teeth. In addition, the magnetic attraction force generated by displacement force depends on the armature reaction. The mathematical model of IPM bearingless motor based on the dq transformation, considering saturation effect, is given. The model can be used to protect dynamic behavior of the IPM bearingless motors. On the other hand, this paper simulates a controller for a saturated IPM bearingless motor, in which the influence of armature reaction on the magnetic attraction force has been taken into account. The performances of the motor are simulated using SIMULINK and MATLAB softwares. Finally, simulations of the dynamic behaviors of a motor with controller are presented and compared with measured result and there exists a good agreement between them.