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Digital Power Reference Note

Taisen Zhuang
Intellectual 400 points
Other Parts Discussed in Thread: UCD3138

Hi I am working on C2000 digital power supply. In the application Note :

Digital Peak Current Mode Control With Slope Compensation Using the TMS320F2803x

It referenced to a manual [2] Biricha Digital Power Ltd. Digital Power Multi-Day Workshop Manual (2010), pp. 168.


Anyone has this manual? That was 2010, Biricha already removed manual from website.

Thanks!!!!

  • 0
    Intellectual 400 points
    Any body have a chance to answer my question?
  • 0 in reply to Taisen Zhuang
    Intellectual 455 points
    I'm sorry that I don't know C2000 platform. I use UCD3138 and Microchip dspic33 platform.
  • 0 in reply to Kami Huang
    Intellectual 400 points

    Thanks for the answer. Do you have any resource to know how to calculate the 2p2z A1 A0 B2 B1 B0 with fz1 fz0 fp1 fp2 and Kdc. I have a hard time to find the document to calculate the Kdc, for PCM and VCM. UCD3138 might have some document to show this.

  • 0 in reply to Taisen Zhuang
    Intellectual 455 points
    I use try and error to fine turn loop gain.
    zh.wikipedia.org/.../PID%E6%8E%A7%E5%88%B6%E5%99%A8
    As I know The other document, you can reference is "UCD3138 Control Theory".
    Here is the hyperlink of this document.
    www.google.com.tw/url;rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB4QFjAA&url=https%3A%2F%2Fe2e.ti.com%2Fcfs-file%2F__key%2Fcommunityserver-discussions-components-files%2F184%2F1727.UCD3138-Control-Theory.pdf&ei=R5BoVeC-I-XTmAWNtYCIAg&usg=AFQjCNHz6_TWpbQiJYuwRp1s3bCW-dp7ig
    If you can not download it you can google the Key word "UCD3138 Control Theory".

    BTW, What's Kdc, PCM and VCM?
    Peak Current Mode, Voltage Control Mode?

    I have one issue of AC input power measurement , if you know something about it. Please give me some hints.
  • 0 in reply to Kami Huang
    Intellectual 400 points
    Thanks for the link of knowledge. I think the UCD3138 is different with F280x family. F280x using 2p2z to and using CSS6 as compiler.
    If you interested about C2000, here is a e2e link to compare UCD3138 and C2000.
    e2e.ti.com/.../267024


    I looked though the UCD3138 Control Theory PDF file, I think what I am talking Kdc is the K0 in the UCD3138 Control Theory PDF file. There are some equation, I could play with (pp8-10). Thank you again for the help!

    PCM is Peak Current Mode, VCM is Voltage Control Mode.

    I don't have too much knowledge about the AC power measurement. Did you try to multi by the ADC current and ADC voltage input in every digital circle and sum them to get the average power? I think C2000 could easy do this by modify the code. I think UCD3138 is using GUI to adjust program, I might wrong, let me know what do you think.
  • 0 in reply to Taisen Zhuang
    Intellectual 455 points

    UCD3138 is using PID control not using 2p2z. Currently, I'm not only design UCD3138 but also Microchip Dsip33FJxxGS606/504.

    UCD3138 still have to write C code. Following is 1 segment of UCD3138 reference code.

    iv.iin_squared_filtered is vector value from ADC.
    I don't know why shift right 15bit in code and need to shift iin_slope_shift bit.
    do you have ideal about it?

    BTW,May I know what's your topology?

  • 0 in reply to Kami Huang
    TI__Guru 57255 points

    Hi Taisen,

    The C2000 forum would be the most appropriate place to ask your original question.  If you wish, feel free to put a new post there:
    https://e2e.ti.com/support/microcontrollers/c2000/


    -Brett

  • 0 in reply to Kami Huang
    Intellectual 400 points
    Hi Kami,

    Sorry answer you post late. I don't have much experience about the UCD3138. Based on my understanding about the 2p2z in the C2000, each module has its resolution, which we call K scaling factor. That is reason why we use different Q15 or Q10 format in different module. Back to your question, I think they are trying convert a Q30 format number into Q24 format, which means Q30/(2^6), down scaling a number. The number will become smaller, however, the percentage of the number reference to full scale keeps the same.

    In your code, (VRECT_SQUARED_SLOW_AVERAGE_SHIFT - 9), 15-9=6, which shifted 6 bit at the very end.

    I am using C2000 full bridge topology.

    Hope this will help you little bit.

    Best Regards,
    Taisen