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115VAC input CCM Boost PFC.....200kHz Switching frequency

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Advanced Member level 5
Jun 13, 2021
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We are bidding for SMPS "take to production" job. However, i think we may be getting taken for a ride, possibly to test us out...VAC = 115VAC and 60Hz. Load = 500W.
The UCC2818 based PFC is set up for 200kHz = switching frequency.
Load = 500W at output of the downstream full bridge.
Boost Diode is FES16GT-E3, a 50ns UF diode.
The output cap is FIVE axial 470uF Tantalums in series (94uH) !!!
The sim i have done confirms output ripple voltage of 73Vpkpk !!!!

The above 94uH is the only PFC output bus cap that i can see. Even though it gets switched by the 500W full bridge, and the aux Flyback.
Is this Candid Camera?....or Beadles's About?....we put it thru to prod...then someone jumps out and tells the world what naff engineers we are.

BTW, front end is fuse, then SMCJ180CA TVS (!!!)...and the 115VAC can go up to 173VAC for 2 seconds (240Vpk).
Max mains transient is said to be 1kV.
Its for "Airborne" use.


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Thanks, have you experience of Offline PFC > you know, EMC conducted limits get low at >150khz...surely its unwise to do PFC at f(sw) > 150kHz? (not to mention reverse recovery related switching losses at that high switchign frequency)?

Ive never heard of anybody doing PFC with UF diode at >120kHz. Can you shed light on the wisdom of offline 115VAC PFC at >150kHz?

Also, a SMCJ180CA TVS on a mains inout of 115VAC that can go up to 173vac (240Vpk) for 2 secods is a disaster waiting to happen?

Sounds like they are really asking some one to take on a full redesign job .... without knowing this is what they are really asking ...
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