**4. Performance Analysis**

*4.1. Prototype Design and FEM Analysis*

To verify the accuracy of the above analysis and study the characteristics of the machine, a prototype is designed and its parameters are illustrated in Table 1.


**Table 1.** The parameters of the HTR-ASD.

A 3D finite element model was established to calculate the electromagnetic parameters. Figure 12 shows the 3D-FEM model and the mesh of the rotor finite element model. Figure 13 shows the no-load magnetic field distribution of the axial and radial views at an excitation current of 6A.

**Figure 12.** Three-dimensional FEM of the HTR-ASD. (**a**) The FEM model of the HTR-ASD. (**b**) Mesh of the rotor finite element model.

**Figure 13.** No-load magnetic field distribution of the axial and radial views. (**a**) The no-load magnetic field distribution of the axial view. (**b**) The no-load magnetic field distribution of the radial view.

Figure 14 shows a comparison between the analytical calculations and the simulation of no-load air gap flux density distribution. This shows that the proposed air gap permeance function and the MEC model of the HTR-ASD are accurate and can be used to calculate the magnetic field of the machine. Figure 15 shows the air gap flux density distribution at different slip speeds and an excitation current of 6A. Additionally, Figure 16 shows the squirrel-cage current density distribution at different slip speeds and an excitation current of 6A.

**Figure 14.** No-load magnetic field distribution of the axial and radial views.

**Figure 15.** Air-gap flux density distribution under different slip speed at 6A excitation current.

**Figure 16.** Current density distribution under different slip speeds and an excitation current of 6A. (**a**) Slip speed = 40 r/min; (**b**) slip speed = 80 r/min; (**c**) slip speed = 120 r/min; (**d**) slip speed = 160 r/min.
