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ultra wide range pfc

Peter Sykes
Prodigy 30 points
Other Parts Discussed in Thread: UC3854B, UCC28070, UCC28051

Hello,

 

I have an application where I need an ultrawide range pfc at about 10W (not a typical application).

We have experience using uc3854b, ucc385xx, ucc28070 over typical wide range input of 84 - 275 Vac (approx 3.5 :1 ).  The Vinac, Vff, Iac type input and multipliers on these devices appears to be designed for this typical input range.

 

Is there a way to use these devices over a 12:1 input range ?  Is there an alternative device that can acheive pfc over such a wide input range ?

 

Regards

 

Peter

  • 0
    Expert 1920 points

    Try the UCC28051. Remember that your output voltage must be higher (rule of thumb says +5-10V at that voltage levels) than the input voltage*sqrt(2).
    You need to manipulate the sensing pins.
    Still 47-63Hz? 

  • 0 in reply to CWilson
    Prodigy 30 points

    Thanks for your repsonse.

    We have looked in detail at a variety of transition mode controllers.

    There are problems with this topology over an ultra wide range input, namley:

    - as the on time becomes longer at low line (30 Vac) you can get a situation where the inductance starts to resonate with the differential mode emi capacitor.  So you no longer have a triangle current waveform and the converter cannot provide any further power.  The solution to this is to use a larger differential emi capacitor.

    - with a larger emi capacitor, at high line (240 Vac) the power factor degrades unnacceptably due to the phase shift in input current caused by the 50 Hz current in the emi capacitor.

    - the other solution, to reduce the inductor value, means that you get a much wider range of switching  frequency.  At high line the frequency is unacceptably high.

    Regards

    Peter