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Original question:

UCC28180: UCC28180 PFC waveform issue

UCC28180: Power management forum

Viet Nguyen5
Prodigy 60 points
Part Number: UCC28180
Other Parts Discussed in Thread: UCC28910,

Hi everyone

I build my PFC follow the guild of TI, the design is shown in the excel file below. The rating power is 1200W. 

when I conduct the experiment, I have a problem with the current waveform, the inductor current waveform is looked nice but it did not come to zero at the transition point.

please help me with this issue.

many thanks

TIDA-00443-Design Calculator.xls

  • 0
    TI__Expert 6080 points

    Hello Viet,

    May you please share the load condition when you observe this behavior. Also, what is the waveform in CH2?

    UCC28910 is a CCM controller but sometimes the operation can be forced to DCM at lighter loads and higher input voltages; if the chosen boost inductor allows ripple current higher than 20%. High-inductor ripple current has an impact on the CCM/DCM boundary and results in higher light-load THD, and also affects the choices for the input capacitor, RSENSE, and Cap at ICOMP pin.

    It would be worthwhile to change this current ripple target to "0.15" or "0.18" and this should allow your deign to avoid DCM operation at light loads.

    Regards,

    Sonal

  • 0 in reply to Sonal Singh
    Prodigy 60 points

    thanks for your reply

    CH2 waveform is Output voltage, I set it 380V

    I test the circuit with 200Ohm resistances load, it means the output power is 700W

    My inductor is 450uH at 0A and drop down to 275uH at 14A so I think it still works in CCM. 

    I have a question, do the EMI filter effect to the input current? because I did not have the EMI filter yet

  • 0 in reply to Viet Nguyen5
    Prodigy 60 points

    thank for your support, I solve my problem.

    The UCC28180 work very well but I use an external gate driver and in the input of  it, I use a filter, it causes the PWM from UCC28180 is no turn off time and extends the turn-on time.

    once again thank for your help.