## 4 Comparative Evaluation of Magnetic Gear Core Materials
### Powder Metallurgy
effective at low frequencies and that SMC materials exhibit approximately 22% lower core losses than conventional electrical steels under high-frequency operation [46; 61; 91; 92; 93]. Figure 15 presents the magnetic permeability curves of the same materials. These curves reflect the permeability behaviors of the materials under varying magnetic field conditions. M400-50A exhibits a higher initial permeability at low magnetic field levels, while Vacodur 50 displays a broader permeability profile across a wide range of magnetic fields. Somaloy 700 HR 5P, on the other hand, offers more limited permeability at low field levels but provides advantages in terms of low core loss and lightweight characteristics. Following the analysis of magnetic characteristics, the variation of core losses with frequency, another critical parameter affecting material performance, has been examined. Below, a comparative presentation of frequency-dependent core losses for M400-50A, Somaloy 700 HR 5P, and Vacodur 50 materials is provided. As seen in Figure 16, the M400-50A material exhibits the highest core loss values with increasing frequency. Somaloy 700 HR 5P and Vacodur 50 show similar loss profiles in the low-frequency range, whereas Vacodur 50 demonstrates a more stable performance at  
Figure 14: B-H characteristic curves of M400-50A, Somaloy 700 HR 5P, and Vacodur 50 materials [94]. Figure 15: Magnetic permeability curves of M400-50A, Somaloy 700 HR 5P, and Vacodur 50 materials [94]. higher frequencies. Notably, at 400 Hz, the core loss of Vacodur 50 is approximately 30% lower than that of M400-50A. These results indicate that Vacodur 50 may be a more efficient choice for high-frequency applications. When selecting materials, not only magnetic characteristics but also factors such as density, core loss, and manufacturing cost must be considered. In this context, Somaloy (a soft magnetic composite) stands out in magnetic gear systems due to its low magnetic losses and high electrical resistivity. Vacodur alloys, on the other hand, are preferred for high-energy-density and efficiency-focused applications due to their high saturation flux density (2.35 T) and low iron losses [95, 96, 97, 98, 99]. In this study, Vacodur 50A was used in a laminated form, which contributes to the suppression of eddy current losses at high operating frequencies. Meanwhile, M400 50A electrical steel finds wide application in electromechanical systems thanks to its high permeability and low core loss [95, 97, 98]. Although SMC materials offer advantages with their low density and resistance to eddy current losses, they may experience increased saturation effects and, thus, higher iron losses in certain geometries due to their relatively low relative permeability when used in block form [67, 78]. The analysis of these fundamental characteristics is consistent with the general trends observed in the radar chart. Vacodur 50A stands out in terms of performance with its high saturation flux density, superior conductivity, and stable permeability profile. M400 50A electrical steel offers a more balanced profile, while Somaloy 700 HR 5P provides advantages in specific niche applications due to its light weight and low core loss. In conclusion, material selection is not solely limited to magnetic performance criteria. Multidimensional parameters such as thermal conductivity, core loss, material density, and manufacturing costs must also be considered. In particular, the use of hybrid materials, such as SMC-steel combinations or Vacodur steel composite solutions, will play a significant role in optimizing the performance of magnetic gear systems in the future. In this regard, material-based improvements in magnetic gear systems should be approached with an interdisciplinary perspective, as this is a critical requirement for increasing system efficiency and torque density.