Analysis of Torque Production in Axial-flux Vernier PM Machines of the MAGNUS Type

The paper presents a study of the torque production in a novel vernier-type axial-flux permanent magnet (PM) machine topology named MAGNUS. Two computational methods are employed, one based on the 3D FEA Maxwell stress calculations on individual stator and rotor components and one based on the analytical derivation of the air-gap flux density harmonics. Examples are provided for a design with a 40-pole spoke-type PM rotor and two stators, one active including a 3-phase winding with 6 concentrated coils wound around main teeth in a single layer arrangement and a second stator that has neither coils nor main slots and is profiled towards the airgap in the same way as the active stator. It is shown that auxiliary small teeth included in the stator main teeth yield a significant increase in the output torque and that the profiled stator has a lower contribution than the active stator to the total torque. A brief report on the ongoing development of a prototype motor is included.