Magnet shape optimization of two-layer spoke-type axial flux interior permanent magnet machines

In this paper, the two-layer spoke-type (TLST) axial flux interior permanent magnet (AFIPM) machine is proposed. Simple flux barriers are added to optimize the air gap flux density, in which way there is no need to change the surface of the rotor. The optimization principle is revealed and the advantages of the TLST AFIPM machine compared with the spoke-type (ST) AFIPM machine are clarified. An optimization design process based on magnetic equivalent circuit combined with idealized and improved air gap flux density waveform is proposed, in which way the calculation time is saved by avoiding an excess of finite element method (FEM) simulations. Finally, 3D FEM simulation is adopted to verify the optimization results.