Re: Inductance calculations

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: acmq@xxxxxxxxxxxxxxxx 

> Original poster: "Gav D" <gdingley@xxxxxxxxx>
>
> Hi all,
> I've been writing some MATLAB code to explore the use of current
> filament analysis to calculate the inductance of the standard coil
> geometries: flat-disk, helical and conical. The results I've been
> getting have been interesting when compared to the traditional
> formulae used in calculating inductance. Assuming my code works, this
> is what I have found:-
>
> Helical: Wheeler works fine as long as the diameter/radius is greater
> than about 5, beyond this the error is small but still present. Below
> this it can get quite way-off.
>
> Flat-Disk: The code generates values of the right magnitude to the
> standard "Wheeler-variation" formula for this coil geometry, but the
> figures are quite different.
>
> Conical: Have not looked at this one yet.
>
> I was wondering if anyone else has looked into this, perhaps have a
> program by which I can compare my own code? Has anyone else noticed
> how inaccurate the standard formulae can be? Perhaps my code is just
> wrong.
>
See my Inca program, at http://www.coe.ufrj.br/~acmq/programs
It evaluates inductances using several precise formulas, and has
also a brute force method for verification.

Antonio Carlos M. de Queiroz