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UCC28180: Ucc28180 Conducted emmisition test fail

Genus Innovation Ltd HIP R& D
Prodigy 10 points
Part Number: UCC28180

Tool/software:

Dear , 

We are getting failure in CE test class A when we apply earthing (grounding and get pass when remove earthing .

Below is the wave form at without earthing 

Below is the wave from with earthing .

Our product is PFC based Rectifier with rating of Output 48V 25A Capacity so rectifier rating is 1.5KW . 

And the we have apply Load as US load whose input is rectifier output 48V and output is 500W .

 

Please suggest 

  • 0
    TI__Mastermind 36940 points

    Hello Genus Innovation, 

    Although the EMI filter is physically connected to the input of the PFC converter, there are three additional DC-DC and DC-AC converters operating simulataneously (according to your block diagram).  All four of these converter stages are EMI noise generators contributing to the conducted noise. 

    This forum is for help with using TI power conversion controllers.  There is little that we can do to help with EMI suppression. However, the large increase in conducted EMI noise when earth-GND is applied suggests that most of this noise is probably Common-Mode noise and much of that noise may be due to grounded heatsinks on your switching semiconductors.  Also possibly due to CM coupling between primary and secondary transformer windings. 

    I suggest to search the web for information and methods for reducing common-mode noise, and conducted EMI in general. 

    Regards,
    Ulrich