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PFC UCC28180 Feedback Loop

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adnan012

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hi,

I need the explanation of the following bode plots given in the attached datasheet of UCC28180.

-> Figure 32. Bode Plot of the Current Averaging Circuit

What is the gain at 4.314kHz?
What is current averaging pole?

-> Figure 32. Bode Plot of the Open Voltage Loop without Error Amplifier

Pulse width modulator to power stage pole fPWM_PS = 1.479Hz ------------------------eq (106)
What does it mean?

-> Figure 34. Closed Loop Voltage Bode Plot

The voltage error amplifier is compensated with a zero, fZERO, at the fPWM_PS pole and a pole, fPOLE, placed at 20
Hz to reject high frequency noise and roll off the gain amplitude. The overall voltage loop crossover, fV, is desired
to be at 10 Hz.

What should be the gain and phase at 10Hz.
 

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  • UCC28180.pdf
    1.7 MB · Views: 51

You say the voltage loop crossover frequency is 10Hz....so the voltage gain should be 1 at 10Hz.
 
Thanks for reply.

Can anyone explain the transfer function? On page 53 how equation 133 is solved?
 

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  • LoopTransferfunction.PNG
    LoopTransferfunction.PNG
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  • equation.PNG
    equation.PNG
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In the UCC28180 there are no such things as equation 133, nor the document has 53 pages.
I can red on post #3 that you are reading the UCC28950 datahseet which actually uses Peak Current Mode control, different than the UCC28180 that uses Average Current Mode control.
Google search has many reading materials about both control methods.
 
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