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# SRM Modeling

- To: <femm@yahoogroups.com>
- Subject: SRM Modeling
- From: "Pradeepkumar Ashok" <pradeepkumar@mail.utexas.edu>
- Date: Sat, 23 Nov 2002 00:29:23 -0600
- Importance: Normal
- In-reply-to: <001001c291b1$b22e1a80$12c6fea9@tmaxdesk>
- Organization: Robotics Research Group
- Reply-to: <pradeepkumar@mail.utexas.edu>

    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 ]

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