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UCC28180: could i replace the Rsense with a current transformer so that i can improve the efficient in high load.

user5496743
Prodigy 60 points
Part Number: UCC28180

I have replace the Rsense  with a current transformer as UP SCH

but the PF is low and input current waveform is so bad。

 

 

  • 0
    TI__Mastermind 34465 points
    Hi,
    The current transformer in your circuit is only sensing the MOSFET drain curremt.
    You need to sense the inductor current, which is the sum of the MOSFET current and the boost diode current.
    So you need to add another current transformer on the diode path. Then add the outputs of the current transformers with isolating diodes.
    Alternatively you can use one dual primary current transformer with one primary loop on the MOSFET drain and the other primary loop on the anode of the BOOST diode

    Regards
    John
  • 0 in reply to John Griffin1
    Prodigy 60 points

    so if  i change the location of the current transformer like up SCH,may it works?

    or can you post a applicationed case to me .

     

  • 0 in reply to user5496743
    TI__Mastermind 34465 points

    A current transformer will not work in the location shown in your sketch because  there is a large DC  component here.

    You can try the circuit shown above.

    The current transformer has a dual primary winding. One primary measured the drain current and the other primary measures the diode current.

    Since the primaries are connected up out of phase the average magnetic flux is zero and the transformer will not saturate.
    A bridge rectifier on the secondary will measure the full inductor current as required.

    Regards

    John