A novel structure for axial flux permanent magnet machines with internal stator

This paper proposes a novel structure for axial flux permanent magnet (AFPM) machines with internal stator (TORUS type) that offers higher torque density without increasing the cost of manufacturing in comparison to similar structures. The key is to employ permanent magnets and ferromagnetic materials in such way that they do not require any back irons for closing flux path in rotors. Therefore, machine becomes lighter and torque density increases. In this Paper the corresponding EMF and electromagnetic torque equations are analytically discussed. Then detailed finite element analysis (FEA) results are carried out to evaluate and verify the performance of the proposed structure for AFPM machines. Finally comparisons between the proposed and conventional structures are presented.