Iron core length of hybrid-magnetic-circuit multi-couple motor

A fatal weakness of a hybrid stepping motor is the uneven distribution of air-gap magnetic field produced by the permanent magnet, which limits the choice of iron core length and volume to performance ratio of a motor. The paper puts forward a hybrid-magnetic-circuit multi-couple motor in which an axial field coil is added on the hybrid stepping motor to compensate for the uneven airgap magnetic field. A model motor is made and analyzed with 2D FEM. The iron core length of an actual motor is discussed.