Affiliations: [a] School of Electrical Engineering and Computer Science,
Seoul National University, Seoul, Korea | [b] Creative Research Engineer Development, Seoul National University, Seoul, Korea
Correspondence:
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Corresponding author: Jong-Suk Ro, Creative Research Engineer Development, Brain Korea 21 Plus, Seoul National University. 1 Gwanangno, Gwanak-gu, Seoul, Korea, Tel.: +82 2 880 7262; Fax: +82 2 878 1452; E-mail: jongsukro@naver.com
Abstract: For a permanent magnet machine, temperature rise due to the losses
in the rotor can affect the performance of the permanent magnet. This is a
critical problem for the designers of electric machine. These losses,
especially eddy current losses in the conductive part of the rotor, cause heat
which cannot easily be mitigate due to the mechanical structure. Therefore, it
is very important to consider the losses in the designing step to ensure that
the machine operates stably. The most common technique of reducing the eddy
current losses is to divide them into smaller parts. The analysis for this
segmentation structure is only possible in 3D-FEM (Finite Element Method) and
though this requires a considerable amount of time during design step.
Therefore, it is necessary to calculate the eddy current losses rapidly and
accurately. In this paper, an eddy current loss analysis method in the retainer
of the permanent magnet machine which has a high power density is proposed.
First, the concept of effective conductivity is introduced to solve the
segmentation problems not to use 3D-FEM. Also, in order to improve the accuracy
of the proposed method, the skin effect which occurs in high speed driving
region is considered and a FFT analysis is also performed on the harmonic
components of air gap flux density. Finally the thermal analysis result which
is based on the loss analysis result is also demonstrated and it is verified to
compare with the thermal experimental results.
