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# Re: [FEMM] Need help in analytical fitting of steel B-H curve

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- Subject: Re: [FEMM] Need help in analytical fitting of steel B-H curve
- From: Keith Gregory <K.Gregory@lboro.ac.uk>
- Date: Tue, 20 Apr 2004 13:26:53 +0100
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I've used simple exponential functions of the form E=a0*F + a1*(1-exp(-b1F)) to model machine open-circuit characteristics (the emf E is a function of mmf F ) and I don't see why it wouldn't work for a B-H curve. It's not usually a brilliant fit but it has a well behaved derivative.
If you want well behaved derivatives then steer clear of polynomials, they don't behave well outside the fitted range.
Keith.

> One approach is an exponential function like that
> described in Paul Victor Birke's 1998 post to
> sci.physics.electromag, which can be seen at
> http://groups.google.com/groups?selm=364EE79A.F279CFE%40home.com&oe=UTF-8&output=gplain
> I've also tried this approach with a further factor on the
> exponential term and have obtained some reasonable-
> looking B-H curves.
> Chris
> > I'm searching for an analytical form of a function
> > with known derivative, other than piecewise
> > polynomial, fitting B-H curve of a given steel.
> > Any paper or advice about this will be appreciated.
> >
> > Thanks in advance.
> > Tsarafidy.
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- References:
  - Re: [FEMM] Need help in analytical fitting of steel B-H curve
    - From: "Chris Holt" <chris.c.holt@aeat.co.uk>

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