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.

PFC output voltage 420VDC?

Status
Not open for further replies.
T

treez

Guest
For a 90-265VAC smps, (100w), why would you make the pfc output at 420V?....i mean, if it were made to 390V then that means less switching losses.....and if it transiently falls to below 360V at high line, then so what?...it just means you need a diode acorss the boost pfc inductor and let the peak of the mains break over the diode and push current into the output cap of the pfc directly?
 

SunnySkyguy

Advanced Member level 5
Joined
Sep 26, 2007
Messages
6,997
Helped
1,709
Reputation
3,416
Reaction score
1,700
Trophy points
1,413
Location
Richmond Hill, ON, Canada
Activity points
51,595
What about margin for PLT? What attenuation of power line transients do you have at switching rate, f.
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
T

treez

Guest
I see your point, but isnt 418v a bit near the 450V "common" voltage of the electrolytics at the output of the pfc?.....as you know, pfc's are slow and if suddenly no-loaded, the vout could go above 450V.

Our transient protection is via a MOV which is after the emi filter, and just before the diode bridge. We put it there because we want it to last longer, and felt the filter would sheild it somewhat. The fuse is right after the input connector as you'd expect.
 

Dan Mills

Advanced Member level 2
Joined
Nov 10, 2013
Messages
510
Helped
239
Reputation
478
Reaction score
229
Trophy points
43
Activity points
4,558
The better sort of PFC chip will stop switching momentarily if it sees the bus voltage > 5% or so above the setpoint, precisely to minimise the issue on a load disconnect transient.

420V is a little higher then I would go absent other constraints, but for example going to 420V might allow the use of a smaller bus cap if the following stage could then tolerate additional ripple, or you might get some more hold up time or something else that was a desirable feature.

Regards, Dan.
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top