SRM Modeling

["Pradeepkumar Ashok" <pradeepkumar@xxxxxxxxxxxxxxx>]

Hi all, 

Has anyone used FEMM to model and evaluate the torque capacity of a
switched reluctance motor? I need help 

My FEM model only gives me half the torque that my analytical
calculations predict. For those interested, the plots and the machine
dimensions are in the file called comparisons.doc . The analytical
method I used was based on a paper by Radun ?Analytically Computing the
Flux linked by a Switched reluctance motor phase when the stator and
rotor pole overlap?. This paper uses the magnetic co-energy method to
calculate torque, while FEMM uses the stress tensor method. Could that
be a reason for the difference? I don?t think so?but I am not sure?

In the models, I used triangle to mesh the air gap between the stator
and the rotor poles (remodel.fem) . I also used a slightly different
model with a finer mesh (.0005) between the stator and rotor poles
(remodel2.fem) to see if this problem was due to my mesh being coarse.
The airgap is .0125 inch and so I felt that .0005 was more than
sufficient. I found the torque output from these two cases to be not too
different. So I went ahead a created a Lua script to plot the static
torque Vs Rotor position Vs Current. (Files inside the folder
torque_sim),and that is how I got the plot shown in comparisons.doc 

Simply put my question is ?Have I modeled the machine correctly?? If so,
I can safely attribute this difference to errors in the analytical
model. Can somebody help ?

Also if anyone else in this group has modeled a SRM using FEMM before,
Can you please let me know how u modeled your machine? and how it
related to experimental data if any

Thanks,
Pradeep


*********************************************************************
Pradeepkumar Ashok
Robotics Research Group-PRC
Campus Mail Code: R9925
University of Texas
Austin, TX 78712
www.robotics.utexas.edu
*********************************************************************

[Moderator's note: The attachement has been placed at:
http://groups.yahoo.com/group/femm/files/srmotor2.zip ]