## 3 Results and Discussion  
Figure 3 shows microstructures of the Nd\({}_{2}\)Fe\({}_{14}\)B bonded magnets fabricated in this research. The polished microstructures (Figure 3a,b) of the Nd\({}_{2}\)Fe\({}_{14}\)B bonded magnets show Nd\({}_{2}\)Fe\({}_{14}\)B particles uniformly and densely dispersed in the sample. The observed powder size from SEM images was approximately 500 \(\upmu\)m.  
In order to confirm the influence of the magnetic flux emitted from the yoke at the time of magnetization, three kinds of magnetization yokes (cases 1 to 3) were designed and  
Figure 3: (a) Low- and (b) high-magnification SEM images of Nd\({}_{2}\)Fe\({}_{14}\)B bonded magnets. Figure 2: Schematics of motor assays and tear-down images of motor indicating stator and rotor (Nd\({}_{2}\)Fe\({}_{14}\)B bonded magnet). are shown in Figure 4. In case 1, the center of the yoke core and the center of the coil were designed to be the same and are shown in Figure 4a. In order to confirm the effect of the magnetizing coil that emits the magnetic field at the time of magnetization, the center of the yoke core and the coil were designed to be the same, and the center of each coil was designed to have a deviation of 100 \(\upmu\)m in the radial direction. This condition is shown in Figure 4b. For case 3, the center of the coil was designed to have a deviation of 50 \(\upmu\)m from the center of the yoke core and is shown in Figure 4c. The designed yokes were fabricated and then subjected to 3D non-destructive analysis with an X-ray, as shown in Figure 5. In case 1, we can confirm that the yoke core and the coil core coincide with each other, as seen in Figure 5a,d. In case 2, the position deviation of each coil is 100 \(\upmu\)m in the radial direction, and is shown in Figure 5b,e. In case 3, the center of the coil was shifted to the left by 50 \(\upmu\)m, as shown in Figure 5c,f. Figure 4: Magnetization yoke design for (**a**) when the yoke center and coil center coincide; (**b**) when the center of the winding coil has a 100 \(\upmu\)m deviation; (**c**) when the center of the winding coil has a 50 \(\upmu\)m shift from the center of the yoke core. Figure 5: Three-dimensional non-destructive analysis with magnetization yoke ((**a,d**) case 1, (**b,e**) case 2, and (**c,f**) case 3). A Nd\({}_{2}\)Fe\({}_{14}\)B rare-earth bonded magnet was magnetized using a yoke in each of the three cases. In order to achieve saturation magnetization, the power condition of the magnetizing yoke was set to 950 V and 800 \(\upmu\)F to generate 1.4 Tesla magnetic fields. To analyze the magnetic flux emitted from each pole of the magnetized yoke, the magnetic properties of each pole of the magnetized magnet were evaluated in the same manner, as shown in Figure 6.  
The surface magnetic flux density of the magnetized Nd\({}_{2}\)Fe\({}_{14}\)B magnet was measured [11,12]. Figure 7 shows the surface magnetic flux density of the Nd\({}_{2}\)Fe\({}_{14}\)B magnet with magnetizing yoke designs in all of the cases. In cases 1 and 2, it was confirmed that a uniform magnetic flux was generated in each pole as a whole. However, in case 3, a low magnetic flux was observed at the 2-7 poles. For a more accurate analysis, we analyzed the flux density, maximum flux peak value, and total harmonic distortion (THD) generated at each pole of the magnet magnetized using the magnetized yoke in cases 1 through 3, as shown in Figure 8 [13]. It can be seen that a constant flux density of 150 and 147 mT is generated in all the poles of the Nd\({}_{2}\)Fe\({}_{14}\)B bonded magnet magnetized with the yokes in cases 1 and 2, as seen in Figure 8a,b. However, in case 3, the magnet density of 135 mT can be observed at magnet poles 2-6, as in Figure 8c. As a result of the maximum flux peak analysis, it was confirmed that the maximum flux peaks of the magnets in cases 1 and 2 were similar. In case 3, we were able to confirm the low flux peak at the 2-7 pole. This finding is due to the non-uniform flux from the magnetized yoke because of the shift at the center of the coil.