High-Performance Low-Cost Electric Motor for Electric Vehicles Using Ferrite Magnets

M Kimiabeigi, James Widmer, Raymond Long, Yi Gao, James Goss, Richard Martin, Timothy Lisle, J.M Soler Vizan, A Michaelides, B Mecrow

Research output: Contribution to journalArticlepeer-review

115 Citations (Scopus)
74 Downloads (Pure)


Permanent-magnet motors with rare-earth magnets are among the best candidates for high-performance applications such as automotive applications. However, due to their cost and risks relating to the security of supply, alternative solutions such as ferrite magnets have recently become popular. In this paper, the two major design challenges of using ferrite magnets for a high-torque-density and high-speed application, i.e., their low remanent flux density and low coercivity, are addressed. It is shown that a spoke-type design utilizing a distributed winding may overcome the torque density challenge due to a simultaneous flux concentration and a reluctance torque possibility. Furthermore, the demagnetization challenge can be overcome through the careful optimization of the rotor structure, with the inclusion of nonmagnetic voids on the top and bottom of the magnets. To meet the challenges of a high-speed operation, an extensive rotor structural analysis has been undertaken, during which electromagnetics and manufacturing tolerances are taken into account. Electromagnetic studies are validated through the testing of a prototype, which is custom built for static torque and demagnetization evaluation. The disclosed motor design surpasses the state-of-the-art performance and cost, merging the theories into a multidisciplinary product.
Original languageEnglish
Pages (from-to)113-122
Number of pages10
JournalIEEE Transactions on Industrial Electronics
Issue number1
Early online date25 Aug 2015
Publication statusPublished - Jan 2016
Externally publishedYes


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