Title: Magnetic and thermal scaling of electric machines

Authors: Jason Pries; Heath Hofmann

Addresses: Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, USA ' Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, USA

Abstract: In this paper, we will investigate performance relationships between electric machines whose dimensions are related by a uniform scaling factor. It is shown, assuming that the voltages applied to the scaled machine windings possess the same magnitude as those applied to the original 'unit' machine, that a corresponding scaling of the time domain ensures the magnetic fields in the machine are consistent with the original, unscaled machine. Furthermore, under the assumption of linear thermal conduction within the machine materials, it is shown that the temperature profile is consistent as well, provided the scaled cooling system can maintain the same temperatures at the machine's boundaries. This serendipitous result allows for straightforward scaling of machine performance characteristics, such as torque-speed curves and efficiency maps, which may be particularly useful for variable-speed and automotive applications.

Keywords: magnetic scaling; thermal scaling; electric machines; vehicle design; design optimisation; numerically efficient analysis; optimal design; temperature profile; torque-speed curves; efficiency maps.

DOI: 10.1504/IJVD.2013.050849

International Journal of Vehicle Design, 2013 Vol.61 No.1/2/3/4, pp.219 - 232

Available online: 05 Dec 2012 *

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