Magnetic field calculation in permanent magnet motors with rotor eccentricity: with slotting effect considered

An analytical technique has been developed to predict the instantaneous magnetic field distribution in the air gap of a permanent magnet motor. The effect of the stator slotting and rotor eccentricity on the magnetic field has been considered. The slotting effect is explained by a newly redefined boundary value problem in polar coordinates in the annular air gap/magnet region of a multipole permanent magnet motor. A perturbation technique is introduced to describe the effect of rotor eccentricity. The analytical method has been validated by a corresponding finite element model. Two prototype motors are used as examples to show the effectiveness of the analytical technique proposed in the paper. The analytical solutions are in good agreement with those obtained by the finite element method, both in amplitude and wave form