Dave, David and Linear induction motors

["Jose Roberto Camacho" <jrcamacho@xxxxxx>]

To: femm@xxxxxxxxxxx
From: Dave Squires <djsquires@xxxxxxxx>
Date sent: Sat, 05 Aug 2000 23:19:12 -0700
Send reply to: femm@xxxxxxxxxxx
Subject: Re: [femm] Linear induction motors

> Just to set the record straight. I did not write the FEMM program.
> It was written by David Meeker. Just want to prevent confusion.
> And I am no expert in using FEMM either. I have learned quite a bit
> and can do some things, but that is far from "expert" level.
> 
> Dave Squires
> 
> Jose Roberto Camacho wrote:
> 
> > To: femm@xxxxxxxxxxx
> > From: Dave Squires <djsquires@xxxxxxxx>
> > Date sent: Sun, 30 Jul 2000 09:39:31 -0700
> > Send reply to: femm@xxxxxxxxxxx
> > Subject: Re: [femm] Linear induction motors
> >
> > > Dr Camacho,
> > > I wonder if you have seen the same thing as I have with FEMM.
> > > It "appears" that magnetic saturation levels are not observed in
> > > the results. For example: silicon core iron as supplied in the
> > > installation of FEMM should saturate at about 2 Tesla, but will
> > > happily show 3 or 4 tesla or more of magnetic flux flowing
> > > through a core. This is obviously not correct. Have you found
> > > a way around this or is it just a simulator limitation? Or is is
> > > that your simulations do not approach magnetic saturation so that
> > > you don't see the problem. My workaround is to increase cross
> > > section so that the flux density goes below the "known" saturation
> > > level.
> > >
> > > Thanks,
> > > Dave Squires
> > >
> > Dear Dave,
> > Actually, I have a Doctoral student that is doing that work. We are
> > starting with the saturation right this moment. The thing is, we
> > made a double face linear induction motor, based on an ordinary
> > induction motor. So, we have the machine working at our lab but
> > we had no idea about saturation aspects. The question was: Are
> > we making an optimized linear induction motor? Probably not, so
> > we decided to use your program to see the saturation level. The
> > machine is working with no load at all, the load is only a flat
> > aluminum disk around 1 cm thick. Propelling the disk the motor
> > current was very small and as your program has proved there was
> > no saturation. We are now increasing the motor current, and we
> > decided to use the Iron-Si 4% magnetization curve. Which is the
> > closest material to our Iron-Si armature. I do not have an answer
> > about the FEMM performance yet, but as soon as I got them, you
> > be sure that I will exchange my experiences with the FEMM
> > comunity.
> > Concerning Gabrielle's idea, I think it is worth to have a good look
> > on it, and this could be a simulation limitation, but this can only be
> > answered with a thorough look at the source code.
> >
> > Many thanks for you attention to my query. I certainly will have
> > many questions to ask you about your program.
> >
> > With my sincere regards,
> >
> > Dr. J.R. Camacho - IEEE Member: 01981539
> > UFU - School of Electrical Engineering - P.O. Box: 593
> > Phone:+55.34.239.4166/250 - Fax: +55.34.236.9530
> > 38400.902 - Uberlandia - MG - Brazil
> >
> > 
> 
> 
> 
> 
> 
> 
Dear Dave and David, 
I must apologize for such confusion, so the e.mail was made to 
Dave and many questions where made also to David Meeker the 
high level expert in FEM here, and should be stated that he "David" 
is the person who did all this work. I expect to be writting to all the 
FEMM commuinty so, I need to add that in our work here we are 
working inside the saturation curve. 10 to 20% above the end of the 
linear range, where normally the synchronous and asynchronous 
machines work under the iron-Si core point of view. We had already 
the information that our machine is working on the linear range, so 
we are wasting iron core really. And the FEMM program is working 
well so far. We are hopping to push it into deep saturation to see 
what happen.
We are also interested in the possibility of coupling the program 
with time domain analysis. Anyone has the experience or a hint on 
how to do it with FEMM.

With my regards and apologies again for the confusion.

Sincerely,



Dr. J.R. Camacho - IEEE Member: 01981539
UFU - School of Electrical Engineering - P.O. Box: 593
Phone:+55.34.239.4166/250 - Fax: +55.34.236.9530
38400.902 - Uberlandia - MG - Brazil