Re: [femm] FEMM + MathCad

[David Meeker <dmeeker@xxxxxxxxxxxxxxxxx>]

Gal Janos wrote:

> Hi,
>
> I am a new FEMM user, dealing with rotating machine design; designing mainly
> large induction motors. Most of our calculations are in MathCad, and I
> intend to use the FEMM for leakage reactance calculation of high skin effect
> rotor slot shapes. Is there anyone who has already connected FEMM to MathCad
> for any reason?
> Is there anyone with the same interest?
>
> Janos Gal
>

Currently, I don't know of a way to hook into FEMM directly from MathCad. One
of the users is working on developing ActiveX automation for FEMM, which
according to the MathCad documentation would allow one to access FEMM directly
from within MathCad. This is a pretty cool extension to the program, but I need
to do a little bit more work to understand how the ActiveX automation stuff
actually works so that I can support it in a future release. (Can anyone have a
good place to start? ActiveX appears to be very poorly documented in the
material that comes with MSVC++).

In the mean time, it is currently possible to access FEMM from within some
mathematical analysis programs like Mathematica, Matlab, etc. without using
ActiveX, via calls to the operating system. This method works, although it is
pretty klunky. The reason that I think that you can't do this approach in
MathCad is that I can't find a way to make operating system calls in MathCad.

Anyhow, I'd been meaning to put up an example of this for a while, and I finally
got around to making one up. See:
http://groups.yahoo.com/group/femm/files/scripting/roters1b.zip
In this example, I've written a Mathematica function that calls FEMM to do
magnetic analysis. Specifically, the example is of a solenoidal actuator. The
Mathematica function takes the plunger position and coil current as inputs and
returns the magnetic field coenergy and force on the plunger. I then call the
function a bunch of times to make some graphs that can be compared to some
experimental data about this particular actuator from a classic book on magnetic
actuator design.

Dave.


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