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Anyone know how to calculate the Kdc in the C2000 HVSFB sample

Taisen Zhuang
Intellectual 400 points

Hi Guys,

I am working C2000 full bridge power circuit. In the controlSUIT sample, HVPSFB_V1.1 sample, excel calculation sheet, there is no explanation about how to calculate the Kdc, fz0 fz1 fp0 and fp1, that would be great if you have some calculation paper.

I found some of them, such as Application Report SPRABE7A – April 2012, they all reference to a report in their calculation: Biricha Digital Power Ltd. Digital Power Multi-Day Workshop Manual (2010), pp. 168.

Anyone has this manual?? Looks like it covered most of the calculation in the manual.

Thanks!

  • 0
    Intellectual 400 points
    Any one have some idea about my questions??
    Thanks!!!
  • 0 in reply to Taisen Zhuang
    TI__Mastermind 27200 points

    Hello Taisen,

    The original selection of pole-zero frequencies for the HVPSFB board was made by mapping ideal PID coefficients.  The frequencies were then adjusted manually to obtain the best response.

    The method described in the application note you referenced, and on those pages in the Biricha Workshop Manual, is an example of pole-zero selection for peak current mode control of a buck converter.  The workshop description is more detailed than the application note; presenting selection for a type 2 compensator in terms of the passive components in the output filter.  We did not do this on the PSFB kit.  The workshop materials are copyright of Biricha Digital Ltd. so we cannot send them out. You may like to contact Biricha directly using the contact details on their website (www.biricha.com).

    You may also find some useful background information on tuning control loops on this site: www.controltheoryseminars.com

    I hope this helps.

    Regards,

    Richard

  • 0 in reply to Richard Poley
    Intellectual 400 points

    Hello Richard,

    Thanks a lot for responding my post.

    Could you explain me more detail about mapping ideal PID coefficients?

    I tried to calculate Kdc B2 B1 and B0 using the method in this ti document:

    http://focus.ti.com/en/download/mcu/biricha_digital_application_note.pdf

    however, when I use the excel in controlSUIT, it gave me a totally different number. What I am trying to do is to find the way to calculate Kdc for Peak Current mode and Voltage Control mode. If you can send me the formula to calculation without send me the full copy of Biricha manual, that would be great!

    I posted another post on C2000 form about GUI example in the controlSUIT, how could I open that in CCS6? I am trying the see how they convert fz1 fz0 fp1 fp2 kdc into B and A.

    Also, my I know why in controlSUIT excel fz1 and fp2 are setting to be same?  from type II control, I could know there is only one fz0 and fp2 as well as Kdc (which is 2*pi*fp1), why we need to set fz1 here and why it is same as fp2?

    Thank you again, I know lots of question, but that would very helpful if you could give me some hint!!

    Best 

  • 0 in reply to Taisen Zhuang
    TI__Genius 10820 points

    Hi Taisen,

    The PID coefficients used in this project are mapped to the 2p2z according to the following relationship (you will see this being used both in the excel sheet and the code).

    b2   = Kd;
    b1   = (Ki-Kp-Kd-Kd);
    b0   = (Kp + Ki + Kd);
    a2   = 0.0;
    a1   = 1.0;

    The excel sheet also provides detailed calculations to derive Bs and As of the 2P2Z controller from fz1, fz2, fp1, fp2 and Kdc. You can follow these calculations by clicking on the entries in the excel sheet which would then display the function in excel. wz1, wz2, wp1, wp2 are calculated first. wr, Q, c2, c1, c0, d2, d1 and d0 are calculated next. Finally b2,b1,b0, a2, a1 and a0 are calculated using these parameters.

    fz2 and fp2 are set to fs/pi.

    I hope this helps.

    Hrishi

  • 0 in reply to Hrishi Nene
    Intellectual 400 points
    Hi Hrishi,

    Thanks for the suggestion. I understand what you talking about how to convert Kp Ki Kd into b2 b1 b0.

    In the application note, there is two different way to calculate b2 b1 b0, PID method and Kdc fz and fp mothod.

    In the fz and fp method, how could I calculate Kdc? In the excel, they give a initial Kdc as input, where this Kdc comes from?

    Thank you Hrishi,

    Best
    Taisen