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How to incorporate core losses in an ANSOFT 2D transformer model

  1. Feb 7, 2013 #1
    I am designing a 2D model of a three-phase core-type transformer in ANSOFT MAXWELL 14.0. While doing so I have encountered a strange problem.

    Start of the problem:-

    While designing the transformer, I wanted to incorporate core losses. So, I did the following steps:-

    Excitations -> Set Eddy Effects -> checked the various core sections in my model (because eddy current effects occur in the transformer core)

    and also

    Excitations -> Set Core Loss - > checked the various core sections in my model (because core loss effects occur in the transformer core)

    Symptoms :-

    Model simulated (using transient solution type) and then gives the following wrong results:

    1) Line currents on the primary side (star-connected) are very high (about 10 times)

    2) Secondary side (delta connected) phase currents lose their phase dependence, i.e. the phase currents are no more 120 degrees apart, they all are in phase now. However, the secondary line currents are Ok though.

    Additional Information :-

    If I do not consider eddy current and core loss effects, then the model simulates to give correct results.

    Please provide me suggestions/hints/solutions to my problem - how to incorporate core losses correctly in my model.
     
  2. jcsd
  3. Feb 12, 2013 #2
    I know nothing about ANSOFT MAXWELL 14.0, so this is a case of the blind leading the blind.

    Forget about the transformer and merely add resistance to the circuit. There will be three resistors, each resistor will be line to line. These resistors will be the core loss.
    Check that the phase voltages are all equal. Check that the phase currents are all equal.

    Still without the transformer but with the resistors, add inductors line to line.(The inductors will be in parallel with the resistors) There will be three inductors. Check voltages and currents the same as before.

    With the resistors and inductors installed, add the transformer. (Resistors and inductors should be between the input and the transformer) Repeat the checks, everything should be OK.

    If there are still problems, post a schematic and someone may be able to help you.
     
    Last edited: Feb 12, 2013
  4. Feb 13, 2013 #3
    Hello Carl Pugh,

    Thanks for your suggestion. I would like to ask a question here - by 'resistors' and 'inductors' do you actually mean core-loss resistances and magnetizing inductances ?

    Thanks,
    Shantanav
     
  5. Feb 13, 2013 #4
    Yes.

    The transformer has a no load loss. (Core loss)
    Divide the core loss by three. Select a resistor that has this loss when connected line to line.
    Calculate the current through one resistor.

    The exciting (Line) current for the transformer should be given.
    The phase current (Current through the inductor) is the line current divided by 1.732.
    The current through the inductor should be the phase current minus the current through the resistor. REMEMBER that the current through the inductor in at 90 degrees from the current through the resistor.

    Good Luck
    Carl
     
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