Instantaneous magnetic field distribution in permanent magnet brushless DC motors. IV. Magnetic field on load

For pt.III see ibid., vol.29, no.1, p.143-151 (1993). An analytical technique is developed for predicting the instantaneous magnetic field distribution in the airgap-permanent magnet region of radial-field topologies of brushless DC motors equipped with a surface-mounted magnet rotor and operating under any specified load condition. It accounts implicitly for the stator winding current waveform and the effect of stator slot openings. The 2-D field analysis, in polar coordinates, combines the armature reaction field component, derived from an analytical determination of the relative temporal and spatial position of the two field components. The predicted open-circuit, armature-reaction, and load field distributions all show excellent agreement with results from corresponding finite element analyses