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Three-Dimensional Modelling of Demagnetization and Utilization of Poorer Magnet Materials for EV/HEV Applications

Lookup NU author(s): Dr Kia Kimiabeigi, Dr James Widmer, Dr Nick BakerORCiD, Dr Richard Martin, Professor Barrie Mecrow



This is the authors' accepted manuscript of an article that has been published in its final definitive form by IEEE, 2016.

For re-use rights please refer to the publisher's terms and conditions.


High performance electric motor designs with ferrite magnets have recently gained interest due to the high and volatile price of rare earth magnets. However, due to the relatively poor coercivity of ferrite magnets, these designs are highly susceptible to demagnetization, as a result of which accurate modelling and better understanding of this phenomenon is particularly important. In this paper, the impact of the motor stack length and level of magnetic saturation on the demagnetization risk are studied based on 3-dimensional finite element simulations and a proposed lumped circuit model. It is shown that reducing the stack length can significantly enhance the demagnetization resistance with the effect being more pronounced for designs with a higher level of magnetic saturation. To benchmark the practicality of the concept, a previously presented high-performance ferrite-based design is modified by using a 30% weaker grade of ferrite magnet whilst shortening the stack length. It is shown that the demagnetization withstand capability of the design was significantly enhanced and exceeded the short circuit requirement with a good safety margin. The theoretical findings have been supported by prototype testing.

Publication metadata

Author(s): Kimiabeigi M, Widmer JD, Baker NJ, Martin R, Mecrow BC, Michaelides A

Publication type: Article

Publication status: Published

Journal: IEEE Transactions on Energy Conversion

Year: 2016

Volume: 31

Issue: 3

Pages: 981-992

Print publication date: 01/09/2016

Online publication date: 21/04/2016

Acceptance date: 14/04/2016

Date deposited: 26/10/2016

ISSN (print): 0885-8969

ISSN (electronic): 1558-0059

Publisher: IEEE


DOI: 10.1109/TEC.2016.2555786


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Funder referenceFunder name
Jaguar Land Rover under the Evoque-E Project
110130Innovate U.K.