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TMS320F28379D: Denormal number (DEN) in C Digtal Power Lib 3P3Z Macro

Basterix
Prodigy 245 points
Part Number: TMS320F28379D
Other Parts Discussed in Thread: C2000WARE, CONTROLSUITE

Hi,

I'm using the 3P3Z Controller from the "C Digital Power Lib".

I realized a kind of ringing on the controller output an sometimes the out variables are DEN.

Is there something wrong with my Coeffs or could it be something else?

Thanks for help.

  • 0
    TI__Mastermind 27200 points

    Could you post the controller coefficients please?  I'll run them and take a look.  Thanks.

    Regards,

    Richard

  • 0 in reply to Richard Poley
    Prodigy 245 points
    Thank you:
    Fc = 1.6k
    f0 = 3.2k
    fz12 = 0.74609k
    fp12 = 3.4312k
    Kdc = 95

    B0= 55.5632693
    B1= -151.4485486
    B2= 137.2538033
    B3= -41.3472263
    A1= 2.6107786
    A2= -2.2594304
    A3= 0.6486519
  • 0 in reply to Basterix
    Prodigy 245 points
    I use the CLA....
  • 0 in reply to Basterix
    TI__Mastermind 27200 points
    Can you confirm what Fc and f0 are in your parameter list please? If neither is the sample frequency, please also let me have that.
    Thanks.
    Richard
  • 0 in reply to Richard Poley
    Prodigy 245 points
    Fc is the crossover
    f0 is the integrating
    Fs = 100k sample
  • 0 in reply to Basterix
    TI__Mastermind 27200 points
    Thank you for the information. I don't think it's the controller coefficients - at least they simulate OK. The TF has a complex pole-pair and three real zeros:

    55.563 (z-0.9543) (z-0.9541) (z-0.8173)
    -------------------------------------------------
    (z-1) (z^2 - 1.611z + 0.6487)

    It could be something outside the controller: possibly the loop is not stable or there's an un-modelled artefact of the plant which causes the ringing. I can't tell from the controller parameters.

    The controller structure used in the DP library is not the most numerically robust. You may like to try computing the 3P3Z law using a function in the digital control library. If you have C2000Ware installed you can find it at:
    C:\ti\c2000\C2000Ware_1_00_00_00\libraries\control\DCL

    There is a third order CLA controller designated DF23_L1. It's not part of DP lib so the calling convention is different, but if you can try that it would be interesting to see if the problem still exists. If not, I suspect it may be the controller structure. Please let us know what you find.

    Regards,

    Richard
  • 0 in reply to Richard Poley
    Prodigy 245 points
    Hey Richard,
    thank you very much checking the parameters.

    I have the controlSuite installed and found the DCL and the UG SPRUI31 in there.

    I will let you know if I can find something.

    Regards,

    Basterix