Loss Analysis and Efficiency Improvement of the Axial Flux Type Generator with Coreless Windings

Abstract

Lately, the application of axial flux type permanent magnet machine with coreless windings for high speed electric machines and electric vehicles have been discussed, from the standpoint of efficiency and size.
In this paper, loss analysis and efficiency improvement of the axial flux type with coreless windings generator are given. The loss is examined based on the experimental data. In order to separate each loss, the prototype was fabricated of which component materials are interchangeable. The eddy current loss generated in the frame structure and the inside of the copper wire are examined. To decrease the eddy current loss, the thin Litz wire and the non -magnetic frame structure are recommended. Finally, the prototype having the output of 750W and the rated speed of 3, 600rpm, has been constructed, which has shown high efficiency of 96% (including machine loss) and 98.9% (excluding machine loss).