Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

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

Status
Not open for further replies.

cupoftea

Advanced Member level 5
Joined
Jun 13, 2021
Messages
2,566
Helped
54
Reputation
108
Reaction score
112
Trophy points
63
Activity points
13,489
Hi,
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.
 

Attachments

  • LT1248 Boost PFC 550W 115vac.zip
    2.5 KB · Views: 80
  • PFC 200khz.jpg
    PFC 200khz.jpg
    226.2 KB · Views: 93

Thanks, have you experience of Offline PFC >150kHz...as 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 ...
 
Last edited:
Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top