• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 62 subscribers
  • Views 1392 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM25117: Droop compensation therory

user4803816
Prodigy 40 points
Part Number: LM25117


I read an article that introduced the method of droop compensation aimed at solving the problem of load sharing. But i don't know the philosophy behind the method, hence could not apply for other applications.

I want to find the original analysis related to this method of TI. 

  • 0
    TI__Mastermind 34875 points

    Hi

    FB node is virtual ground, then:

    Vout/Rfb1=Vcomp/Rcomp 

    So Vcomp=Vout*Rcomp/Rfb1

    For peak current model control, Iout=K*Vcomp

    so Iout=Vout*K*Rcomp/Rfb1

    this means the Vout is proportional to Iout, this is essential feature for droop compensation.

    B R

    Andy

  • 0
    TI__Mastermind 34875 points

    Correct typo:

    FB node is virtual ground, then:

    Vout/Rfb2=Vcomp/Rdroop

    So Vcomp=Vout*Rdroop/Rfb2

    For peak current model control, Iout=K*Vcomp

    so Iout=Vout*K*Rdroop/Rfb2

    this means the Vout is proportional to Iout, this is essential feature for droop compensation.

  • 0 in reply to Andy Chen
    Prodigy 40 points

    Hi Andy

    Thank you for your answer, i guess if i use the droop compensation, then maybe the control system's dynamic behavior will have big change. As usually for the voltage loop the type2 compensator is used.

    So in which condition you will suggest the droop compensation, as i see it will not provide accuracy for the output set point as there is no intergral element which is included in common type2 or PI compensater. 

  • 0 in reply to user4803816
    TI__Mastermind 34875 points

    Hi 

    With droop compensation, You need to evaluate load regulation or dynamic at point of load, NOT the output voltage on output cap close to converter. 

    if you need more accurate output voltage at POL, you can adjust Vout by bias the FB node with output voltage or current of load current sense device. the converter control loop still has high gain PI integrator by this way.

    B R

    Andy