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Mitsutoshi Natsumeda, Sumitomo Special Metals CO.,LTD

Abstract

Recently, various magnetic circuits have been precisely designed by a computer through the improvement of magnetic field analysis techniques, such as a finite element method.
When permanent magnets, such as NEOMAX, is used in a magnetic circuit, the demagnetization of the permanent magnet by temperature rise must be considered.
In the conventional method, though the qualitative estimation of demagnetization was possible, it was difficult to calculate the amount of demagnetization and therefore the magnetic circuit calculation after the demagnetization was insufficient.
Since permeance coefficients of each magnet element depend on the part of the magnet block, some magnet elements having lower permeance coefficient are easy to be demagnetized. Therefore, the amount of demagnetization was analyzed by-using re-defined B-H curve after the temperature rise and each permeance coefficient. This report shows the comparison between the calculated and the measured results after the demagnetization.
Key Words: finite element method, demagnetization, permeance coefficient, B-H curve