Re: [TCML] NST Measurements

[DC Cox <resonance@xxxxxxxxxxxx>]

I have Maxwell and it works good, but I'm certainly not a "master" in its
applications.

It does very nice asisymmetric and also symmetric electrostatic plots on
coils.

If you have come our Teslathon this next fall you can teach us how to use it
better.

Dr. Resonance





On Wed, Jan 21, 2009 at 10:31 AM, Kurt Schraner <k.schraner@xxxxxxxxxxx>wrote:

> One of those free finite element programs Jim Lux is mentioning, is David
> Meekers FE method magnetics simulator FEMM. I was using it for some of my
> induction coils, and it was not really hard to learn, giving results of i.e.
> L1,L2, which were in good agreement with my measured values.
>
> http://femm.foster-miller.net/wiki/HomePage
>
> Citing David Meeker:
> "A Windows finite element solver for 2D and axisymmetric magnetic,
> electrostatic, heat flow, and current flow problems with graphical pre- and
> post-processors."
>
> Well, my induction coils are axisymmetric, and there may be some error in
> modeling transformers as 2D. (The program version I was using is 3.2 of Dec
> 3, 2002 while the actual Version is 4.2).
>
> Regards, Kurt
>
> jimlux wrote:
>
>> Godfrey Loudner wrote:
>>
>>> It's too bad we can't get hold of the sophisticated software
>>> companies use to design transformers. The ones I saw advertised on
>>> the web cost about $80,000 or can be rented. They seem to use finite
>>> elements to deal with the horror of the differential equation
>>> involved. The programs can even deal with the thermodynamics of the
>>> transformers. I'm beginning to believe that the details of the
>>> mathematical methods are kept secret for financial reasons. The
>>> software Mathematica keeps some of their methods secret and that is
>>> a real horror. It would be much fun to enter the geometry of a mot
>>> or NST and run the calculations in particular cases. Godfrey Loudner
>>>
>>>
>> There's no secret math in finite element programs like Maxwell or HFSS
>>
>> What you get for your tens of $K is a useful user interface, both for
>> data entry and for looking at the results, lots of library support in
>> terms of materials and prebuilt models, etc.  You also get good
>> interfaces to CAD/CAM software (so you can model the part you're
>> actually going to build, without having to re-enter the model)
>>
>> They also have fairly efficient computational algorithms for doing the
>> FEM, rather than brute forcing it with a tiny time step and hoping
>> that numerical precision doesn't bite you.
>>
>> All of this costs real money to write in the first place, and it saves
>> engineers time to use it, so they can justify the price they charge
>> for it.  If a senior engineer costs about $250k/yr (salary, benefits,
>> office space, etc.) and you save 20% of their time, you've just
>> justified an analysis program that costs $50k/yr.  Whether or not an
>> engineer spends enough time doing analysis (as opposed to adjusting
>> Gantt charts in MS Project and doing powerpoint presentations) is
>> another factor, but I will say that modern design/analysis tools are
>> wonderful.
>> There ARE open source/free analysis codes out there, but after using
>> them, you'll see why folks are willing to pay the kilobucks, if
>> they're doing it for work. The free codes are often limited in terms
>> of model size, or require you to write software to describe what it
>> is you are modeling (i.e. you get the FEM grid stuff, but YOU have to
>> load the grid and constraints), or were done as a senior
>> project/master's thesis, and are 90% complete and untested, or, are
>> some toy built in BASIC back in the 1980s as demo on a TRS-80, etc.
>>
>> They won't import IGES or DXF, etc.  They might have bugs. They might
>> require doing many runs to understand numerical precision effects (you
>> can't just chop things up into a really fine grid and sum them all).
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxxxxxx
>> http://www.pupman.com/mailman/listinfo/tesla
>>
>
>
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
>
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla