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

[Keith Gregory <K.Gregory@xxxxxxxxxxx>]

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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