Evaluation of the Self-Cooling Performance of a Flux-Switching Permanent Magnet Machine With Airfoil-Shaped Rotor

The objective of this article is to evaluate the self-cooling performance of a novel integrated flux-switching permanent magnet (FSPM) machine with an airfoil-shaped rotor. The rotor of the proposed integrated machine is functioning as both a rotor of the motor as well as an axial fan. It rotates to draw air from the ambient into the rotor and accelerate the flow through the rotor stage. The high-speed flow provides forced convection to the rotor, stator, windings, and magnets. Therefore, self-cooling is achieved. Accounting for manufacturing challenges of the airfoil blades, three-dimensional (3-D) printed blade caps are designed and assembled over the laminated rotor poles for the airfoil-shaped rotor. The electromagnetic performance of the continuous-skewed stator slot is compared with the step-skewed stator slot. Three housing configurations are proposed in terms of housing with radial inlets, housing with axial inlets, and no housing. The electromagnetic performance is verified by 3-D finite element analysis (FEA). The convective heat transfer coefficients of the three housing configurations are calculated by analytical methods and numerical simulations by 3-D computational fluid dynamics. The effect of encapsulations on the windings is also evaluated by FEA. A prototype machine is built and tested. Experimental results of measured temperature distributions on the stator and windings are included to validate the numerical simulation results.