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Re: [FEMM] How does femm handle coercivity and core losses?



robert Macy wrote:

I'm trying to predict the performance of an inductor made
using two different core materials.

First core material, has extremely low coercivity, less
than 0.003 Oersteds. The second, has a coercivity of 0.05
Oersteds. The two core materials are placed into the
materials section using their BH characteristics.


When running AC analysis, does femm take into account the
hysteresis losses associated with a more "open" curve core
material?

- Robert -

Hysteresis loss can be modeled via the "hysteresis angle" parameter. This parameter can sometimes be obtained via manufacturer's spec sheets as complex permeability (e.g. for ferrites), by noting that the hysteresis angle used in FEMM is the negative of the argument of the complex permeability. If no complex permeability is given, one has to end up sweating out some appropriate parameter from "raw" core loss data, which can be nontrivial to do.

For a reference on how this sort of thing works, check out:

Methods for magnetically nonlinear problems involving significant hysteresis and eddy currents
Jack, A.G.; Mecrow, B.C.;
Magnetics, IEEE Transactions on , Volume: 26 Issue: 2 , Mar 1990
Page(s): 424 -429


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David Meeker
Senior Engineer
Foster-Miller, Inc.
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