Instantaneous magnetic field distribution in brushless permanent magnet DC motors. II. Armature-reaction field

For pt.I see ibid., vol.29, no.1, p.124-135 (1993). An analytical technique for predicting the open-circuit magnetic field distribution in the airgap/magnet region of a brushless permanent-magnet DC motor equipped with a surface mounted magnet rotor and a slotless stator was presented in Pt.I. In the present work, the analysis is extended to the prediction of the armature reaction field produced by the three-phase stator windings. As before, th motor model is formulated in polar coordinates and accounts for the large effective airgap, but it is not developed further to consider the effect of winding current harmonics on the airgap field distribution. Predicted instantaneous armature reaction field distributions are validated by a comparison with corresponding finite element calculations