Presentation Information
[P1-40]High Magnetic Flux Rotor Core for IPM Motor through Partial Non-Magnetic Improvement of Silicon Steel
*Norihiko Hamada1, Hironari Mitarai1, Katsunari Oikawa2, Satoshi Sugimoto2 (1. Aichi Steel Corporation (Japan), 2. Tohoku University (Japan))
Keywords:
interior permanent magnet(IPM) motor,rotor core,leakage flux,partial non-magnetic improvement,Nd-Fe-B magnet
Leakage flux in the rotor core of a bridge remains a persistent issue for interior permanent magnet motors and has yet to be resolved. It is well-established that partial non-magnetization of the bridges reduces magnetic flux leakage, resulting in a rotor with higher magnetic flux [1]. In a preliminary experiment [2], we attempted to melt and mix the bridges of the rotor core with a Ni-Cr alloy wire using laser heating, based on the Schaeffler diagram [3]. This method produced a rotor with partial non-magnetization of the bridges. However, due to welding defects and the coupling of laminated bridges, these rotors were unsuitable for practical applications. To address this, we pre-treated the silicon steel sheets–intended to become the rotor bridges–by partially non-magnetizing them before laminating them to form the rotor core. We then evaluated the performance of the fabricated rotor.
Partial non-magnetization treatment involved mixed and melt with silicon steel sheets and Ni-Cr-B alloy powder by laser. A rotor (8 poles, 80 mm outer diameter, and 30 mm height) was produced by pressing and laminating the silicon steel sheets. Two types of permanent magnets were used for the experiments: one was an Nd anisotropic bonded magnet with a residual flux density (Br) of 0.77 T, and the other was an Nd sintered magnet with a Br of 1.3 T.
Magnets were inserted into the rotor, and the surface magnetic flux density at the center of the pole was measured. A conventional rotor was also fabricated for comparison, and the same evaluation was performed. The results, shown in Figure 1, indicate that the surface magnetic flux density of the sintered magnet was higher than that of the bonded magnet. However, both magnets experienced similar flux increases, as the amount of magnetic leakage in the bridge was the same for both types of magnets.
[Acknowledgement]
This research was supported by a Green Innovation Fund subsidy project (JPNP21026) of the New Energy and Industrial Technology Development Organization, which is a national R&D agency.
[References]
[1] M. Mita et al., J. Appl. Phys. 93 (2003) 8769.
[2] N. Hamada et al., Mater. Trans., 64 (2023) 1058.
[3] M. A. Pugacz, Weld. J. 23 (1944) 536s.
Partial non-magnetization treatment involved mixed and melt with silicon steel sheets and Ni-Cr-B alloy powder by laser. A rotor (8 poles, 80 mm outer diameter, and 30 mm height) was produced by pressing and laminating the silicon steel sheets. Two types of permanent magnets were used for the experiments: one was an Nd anisotropic bonded magnet with a residual flux density (Br) of 0.77 T, and the other was an Nd sintered magnet with a Br of 1.3 T.
Magnets were inserted into the rotor, and the surface magnetic flux density at the center of the pole was measured. A conventional rotor was also fabricated for comparison, and the same evaluation was performed. The results, shown in Figure 1, indicate that the surface magnetic flux density of the sintered magnet was higher than that of the bonded magnet. However, both magnets experienced similar flux increases, as the amount of magnetic leakage in the bridge was the same for both types of magnets.
[Acknowledgement]
This research was supported by a Green Innovation Fund subsidy project (JPNP21026) of the New Energy and Industrial Technology Development Organization, which is a national R&D agency.
[References]
[1] M. Mita et al., J. Appl. Phys. 93 (2003) 8769.
[2] N. Hamada et al., Mater. Trans., 64 (2023) 1058.
[3] M. A. Pugacz, Weld. J. 23 (1944) 536s.
