Thermal Modeling of Flux-Switching Permanent-Magnet Machines Considering Anisotropic Conductivity and Thermal Contact Resistance

The technique to consider the anisotropic thermal conductivity and thermal contact resistances, as well as convection heat transfer in the air gap in the 3-D thermal modeling of electrical machines, is elaborated in detail and incorporated in the finite-element (FE) package developed with the FE program generator (FEPG) for thermal modeling of the flux-switching permanent-magnet (FSPM) machine. A dissymmetric model to simulate the convection heat transfer in the air gap with different stator and rotor poles is proposed. Moreover, a lumped parameter (LP) thermal model of this machine is also established to calculate the temperatures of the main machine components for comparative study purpose. The calculation results with different methods are verified with experiments. The conclusion highlights the importance of considering thermal contact resistance between windings and the stator core. The proposed model can reduce the total number of mesh comparing with traditional FE thermal model and eliminate complicated establishment of the thermal network and calculation of thermal resistances comparing with LP method.