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Machines 2014, 2(2), 120-133; doi:10.3390/machines2020120

A Complete Design of a Rare Earth Metal-Free Permanent Magnet Generator

1,* , 1
1 Division of Electricity, Department of Engineering Sciences, Uppsala University, Box 534, Uppsala SE-751 21, Sweden 2 Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK
* Author to whom correspondence should be addressed.
Received: 25 February 2014 / Revised: 2 April 2014 / Accepted: 13 May 2014 / Published: 16 May 2014
(This article belongs to the Special Issue Advances in Machinery for Renewable Power Generation)
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The price of rare-earth metals used in neodymium-iron-boron (NdFeB) permanent magnets (PMs) has fluctuated greatly recently. Replacing the NdFeB PMs with more abundant ferrite PMs will avoid the cost insecurity and insecurity of supply. Ferrite PMs have lower performance than NdFeB PMs and for similar performance more PM material has to be used, requiring more support structure. Flux concentration is also necessary, for example, by a spoke-type rotor. In this paper the rotor of a 12 kW NdFeB PM generator was redesigned to use ferrite PMs, reusing the existing stator and experimental setup. Finite element simulations were used to calculate both electromagnetic and mechanical properties of the design. Focus was on mechanical design and feasibility of construction. The result was a design of a ferrite PM rotor to be used with the old stator with some small changes to the generator support structure. The new generator has the same output power at a slightly lower voltage level. It was concluded that it is possible to use the same stator with either a NdFeB PM rotor or a ferrite PM rotor. A ferrite PM generator might require a larger diameter than a NdFeB generator to generate the same voltage.
Keywords: rare earth metal-free; permanent magnet; synchronous generator rare earth metal-free; permanent magnet; synchronous generator
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Eklund, P.; Sjökvist, S.; Eriksson, S.; Leijon, M. A Complete Design of a Rare Earth Metal-Free Permanent Magnet Generator. Machines 2014, 2, 120-133.

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