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Subject: EMAG: 2D filed analyses of a brushless PM motor
Author: Andrej Stermecki
Date: 2002-06-07 05:59:00

Dear Sirs,

There's been a week around and here I am again seeking help with some new
problems. A week ago I explained in my letter that I am trying to do a
static 2D field
analyses of a brushless PM motor as a project for my final university
degree. Afterwards, I was
looking forward to be already near the solution, because I have already got
the result for magnetic flux density B.

And now I'm trying to calculate the torque. The torque I get is a way out of
expected,so there must be something wrong. I know that it is hard, if not
impossible
for you to say what exactly is the problem, but I will at least try to
explain as good as
possible what I believe it could be incorrect. And again, I would really
appreciate
any help of yours concerning this thoughts and possible solutions.

1. Magnetic flux density B seems to be OK (around 0.2T in the air gap).
By the way, is there any command (macro) that makes B arrangement along
the air gap possible to be seen?

2. I get different torque results depending on what type of element I am
using. I use PLANE13 or PLANE53. Is there any problem with any of those two
types
of element?

3. Because of the cylindrical geometry of the motor, I am building the whole
model in the cylindrical coordinate system CSYS,1 and LOCAL,12,1 is
attributed to all elements with AATT,X,,,12. So also the areas attributed
with current density are built in cylindrical CS. Should I attribute the
areas with current density in some other coordinate system, for instance in
Cartesian KS? I am transcribing current density to the areas by the command
BFA,ALL,JS,,,I (all necessary areas are selected with ASEL before). The
current density is 2,752E+06A/m2.

4. In /SOLU1 I select the elements in the middle layers of air gap (air gap
is divided into four layers, so I select the 2nd an the 3rd) and I ascribe
to those elements the magnetic force boundary conditions by
FMAGBC,'NAME_OF_THE
COMPONENT_OF SELECTED LAYERS'. After solution I am calculating torque by
the command: TORQC2D,R,144, where R is a distance from the center to the
exact middle of the air gap.

I guess I might be asking for too much, and that it is very unlikely for
anyone to be able to find my mistake just through my writting and on such
distance. But
to go on with my work I really need some help with this problem or at least
some
hints in which direction to look for the mistake and its solution.
I assume there must be something wrong with torque calculation or with
current density transcribing, because it seems that magnetic flux density B
is OK
(0.2T -0.3T in air gap).
Can you tell me, please, how to check if the current density is transcribed
correctly and how to be sure, that all boundary conditions are correct?

To you I might seem so lost in my work, but one of the reasons is, that I do
not have any example of any analysis similar to this one that I'm working on
at the
moment. All the paper materials I have are just the documents bought with
the
Ansys5.7.1 (Modeling and meshing guide , Electromagnetic Filed Analyses
Guide.) and there is no example of the electro motor analysis.

You can see I am very limited in information in my research. So I would
deeply appreciate it, if you can let me know about or possibly recommend me
any literature or even better some useful Internet sites concerning this
particular matter.

Thanks again for your time to read this through and your efforts to give me
any useful direction to the solution of my problem. I hope one day I might
be able to offer some help in return, too. But until then, I have to pass my
finals, so it is very possible that this is not my last problem seeking for
solution and for your help.

I hope to hear from you soon and wish you a nice day,

Andrej STERMECKI
University of Maribor
Faculty of Electrotechnics

Slovenia, Maribor, 7th June 2002

Posts possibly associated with message #38583AuthorDateScore
38583EMAG: 2D filed analyses of a brushless PM motorAndrej Stermecki2002/06/07 
38933Re: EMAG: 2D filed analyses of a brushless PM motorBill Bulat2002/06/19 
38952Re: EMAG: 2D filed analyses of a brushless PM motorAndrej Stermecki2002/06/19 
39022Re: EMAG: 2D filed analyses of a brushless PM motorBill Bulat2002/06/20 
39278Re: EMAG: 2D filed analyses of a brushless PM motorAndrej Stermecki2002/06/28