Simulink - Warning algebric loop

Discussion in 'Programmer's Corner' started by Adam Brave, Mar 27, 2014.

  1. Adam Brave

    Thread Starter New Member

    Mar 26, 2014
    13
    0
    Hi,

    I've a circuit on simulink where I collect three phase currents and voltages from a measuremnt bus and then use them in blocks of abc-to-dq transformation. When I run the circuit for the first time I get the following message:

    Code ( (Unknown Language)):
    1.     This algebraic loop may be resolved when the subsystem option 'Minimize algebraic loop occurrences' is selected on some or all of the atomic and enabled subsystems in this algebraic loop.
    So, I check the option "minimize algebric loop occurrences and then I get the following message:

    Code ( (Unknown Language)):
    1. Warning: If the inport 'dfig_controloGSC_v2/Controlo GSC/Iabc' of subsystem 'dfig_controloGSC_v2/Controlo GSC'
    2. involves direct feedback, then an algebraic loop exists, which Simulink cannot remove. Consider clearing the
    3. 'Minimize algebraic loop occurrences' parameter to avoid this warning.
    4. > In testeGSC at 65
    5.   In run at 74
    6. Warning: If the inport 'dfig_controloGSC_v2/Controlo GSC/Vabc' of subsystem 'dfig_controloGSC_v2/Controlo GSC'
    7. involves direct feedback, then an algebraic loop exists, which Simulink cannot remove. Consider clearing the
    8. 'Minimize algebraic loop occurrences' parameter to avoid this warning.
    I think this loop is affecting my results but I need to do the abc-to-dq transformation. How can I solve this? Would a block delay help in this situation?

    Thanks in advance
    [​IMG]
     
  2. ActivePower

    Member

    Mar 15, 2012
    155
    23
    It is likely that you are looping back onto a single connection without meaning to. In other words, you've probably tied a signal back onto itself or a similar signal which makes the compiler unable to decide the correct discrete value of the result.

    I know this sounds vague but your images don't seem to convey everything you have inside your subsystem. Look around and with some luck, you'll be able to narrow it down.

    HTH.
     
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