Abstract
Ferrite-bonded magnets have been extensively used in small brushless DC (BLDC) motors for low torque applications such as fans and pumps. In particular, some motors of them with ferrite-bonded magnets, frequently called as plastic magnets, do not have a rotor core in order to reduce manufacturing costs and inertia of the rotating part. Accordingly, the magnetization distribution of the bonded magnets has a polar anisotropic direction to secure more magnetic flux. As a result, the magnetization orientation of the magnets is highly significant to accurately predict the performances of the BLDC motors. This paper deals with the magnetization analysis of the polar anisotropic ferrite ring magnet applied to an outer rotor type BLDC motor. The motor is employed for an electric water pump, and its rotor including the impeller consists of only the ferrite-bonded magnet material and made by injection molding. Consequently, a magnetizing fixture and an impulse magnetizer are not used for the magnetization of the outer rotor type motor. Instead, samarium–cobalt (SmCo) magnets having a relatively high curie temperature are applied for generating magnetic field. Finally, this paper presents a process to determine the anisotropic orientations of a ferrite ring magnet by finite element method. In addition, the validity of the analysis method is verified by test results.
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References
Ormerod J, Constantinides S (1997) Bonded permanent magnets: current status and future opportunities. J Appl Phys 81(8):4816–4820
Borghi CA, Casadei D, Cristofolini A, Fabbri M, Serra G (2002) Minimizing torque ripple in permanent magnet synchronous motors with polymer-bonded magnets. IEEE Trans Magn 38(2):1371–1377
Jung T-U (2014) Low cost design study of brushless dc motor for electric water pump application. J Electr Eng Technol 9(3):942–949
Fasil M, Mijatovic N, Jensen BB, Holboll J (2015) Performance variation of ferrite magnet PMBLDC motor with temperature. IEEE Trans Magn 51(12):8115106
Okada Y, Inoue H, Fusayasu H, Nishida H (1997) Analysis for permanent magnet motor taking account of magnetizing process. IEEE Trans Magn 33(2):2113–2116
Kim HJ, Koh CS, Shin PS (2010) A new anisotropic bonded NdFeB permanent magnet and its application to a small DC motor. IEEE Trans Magn 46(6):2314–2317
Nakata T, Takahashi N (1986) Numerical analysis of transient magnetic field in a capacitor-discharge impulse magnetizer. IEEE Trans Magn 22(5):526–528
Sakai T, Nakamura K, Morii A (1991) Plastics magnet manufacturing process: mixing, kneading, and injection molding. Int Polym Proc 6(1):26–34
Kitamura S, Ishihara Y, Todaka T, Inoue Y (1996) Magnetic field analysis of DC brushless motor considered volt-ampere characteristic of feedback diodes. IEEJ Trans Ind Appl 116(12):1268–1275
Nakata T, Takahashi N (1986) Finite element method in electrical engineering, 2nd edn. Morikita Shuppan, Tokyo
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This research was supported by the Academic Research Fund of Hoseo University in 2017 (20170065).
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Kim, SI., Lee, SJ., Lee, JJ. et al. Magnetization Analysis for Outer Rotor Brushless DC Motors Using Polar Anisotropic Ferrite Ring Magnets. J. Electr. Eng. Technol. 15, 1189–1194 (2020). https://doi.org/10.1007/s42835-020-00397-7
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DOI: https://doi.org/10.1007/s42835-020-00397-7