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Original question:

UCC28180: heating issue at higher switching frequency

UCC28180: Outputvoltage 150...200V

John
Prodigy 30 points
Part Number: UCC28180

For a project with BLDC motor, we need a PFC circuit which has an input voltage range of approx. 90V...130V and a max. output voltage of approx. 150...200V (not yet finalised).The output power should be approx. 800W.

We have already successfully used the UC28180 controller in another project. The input voltage there was approx. 230V and the output voltage was approx. 390V at approx. 1kW.

This is why we would also like to use the PFC controller in the new project.


I have general questions about this:


-is a realisation with the low input and output voltages on UC28180 even possible? Or would it be better to choose a different controller?
-How should the ratio between input voltage and output voltage be assessed with regard to EMC? Is a smaller or larger ratio better?
-What approach should be taken to minimise the installation space? We have very little space in this application. 80mm x 170mm x40mm

Thanks for the support, I really appreciate it

John

  • 0
    TI__Mastermind 31110 points

    Hello John, 

    Thank you for considering using the UCC28180 in your next project. 

    The UCC28180 is certainly a good choice for a low-voltage input application.  The output voltage should be at least ~10V higher than the highest input peak.
    Your tentative input range of 90V to 130V is in RMS, while the output is DC.  The peak of 130Vac is 184V.  I suggest to set Vout = 200Vdc. 
    If your final range expands higher, the output should be adjusted higher.  

    For EMC consideration, lower voltages result in lower common-mode noise, but may have higher differential mode noise.  However, the higher DM may be easier to filter than the CM.

    I'm not sure how to advise on space utilization. If you have access to reliable forced air for cooling, it can go a long way to reducing heatsink and magnetics size.
    If natural convection colling is the only option, orient the components to optimize the cooling effectiveness of the convection currents.  

    Regards,
    Ulrich

  • 0 in reply to Ulrich Goerke
    Prodigy 30 points

    thanks you Ulrich for the quick and precise answer.