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UCC28180: square waveform input to PFC

Kai Nomiyama
Expert 5595 points
Part Number: UCC28180

Hi team,

I have a general question about Square waveform input to PFC

could you let me know the reason why PFC gets damage or stops output when input waveform is not sinewave but square wave?

Is it no problem if UCC28180D input is square wave?

if there are any problem, could you let me know the workaround to address square waveform with UCC28180?

Generally input from UPS to PFC is sinewave but some input from UPS to PFC is square waveform.

in that case of square waveform input, some PFC gets damage or stops output due to square waveform.

Thanks,

Regards,

Kai

  • 0
    TI__Mastermind 34465 points
    Hello Kai,
    I understand that the less expensive UPS's have a square wave output since it is easier to generate a square wave inverter than a sine wave inverter.
    With this source of power, the pfc circuit needs to rectify the square wave and add a small filter to remove the high dV/dt from the high voltage signal. This will give an almost DC signal as input to the pfc. With this small filter and rectifier the UCC28180 will work as required.
    If you don't have a filter on the input, the boost MOSFET may see large inductive voltage spikes which will damage the device.
    It may be enough to just add a small capacitor after the bridge rectifier.
    Regards
    John
  • 0 in reply to John Griffin1
    TI__Expert 5595 points

    Hi John,

    Could you let me double check?

    you described "a small filter", "an almost DC signal", "this small filter", "rectifier", "a filter", "a small capacitor".

    However, I couldn't understand correctly waht filter and cap are these in PFC...

    I attached my understanding in attachment so could you see and correct it if there are anything wrong?

    especially, I could find the difference of Vds when I change input from sinewave to square wave.

    However, When I add cap, I cound not see any difference.

    How do I add a small filter?

    UCC28180 sinewave vs squarewave.pptx

    Thanks,

    Regards,

    Kai

  • 0 in reply to Kai Nomiyama
    TI__Mastermind 34465 points

    Hello Kai,

    Now I see that this is an issue with a simulation that you are having.

    Have you any real world tests done on this ?

    Regards

    John

  • 0 in reply to John Griffin1
    TI__Expert 5595 points

    Hi John,

    I don't have test data.

    My customer see the article in web about this square waveform topic.

    Actually They are considering to use UCC28180 so if there are any workaround to protect their system from square waveform, they want to know it and also they want to know the root cause why PFC gets damage.

    My question is clear.

    - the reason why PFC gets damege from square waveform

    - workaround to protect from square waveform

    if you are ok, could you send me email directly?

    Thanks,

    Regards,

    Kai

  • 0 in reply to Kai Nomiyama
    TI__Mastermind 34465 points
    Hi Kai,
    Sure I can contact you directly or you can contact me
    johngriffin@ti.com
    I would like to see the article about a square wave damaging the MOSFET.

    Regards
    John