Offline full-bridge SMPS… need help

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#1,023
do you have any way to measure inductance? If you do, its pretty simple, but like I said, books... you can calculate... in any case you can oversize those things, and have no worries. Just note that on PFC you will need gap, on smps not
You can always find someone to build it for you, just give them core and specs... or just specs, really depends who you find
 
#1,026
Krisfr said:
Yes I can measure HCR, with a cheapo meter I bought on EBay for 10 bucks...
Works okay, close enough for me anyway...
What would you guess at the cost of the Transformer? How long would it take to get it...

Thanks
Click to expand...
to get it made? I would guess a lot more then diy, you would get is pretty fast I think, say 1-3 weeks, but I also have no idea... you should ask and see what they'll say
 
#1,029
The circuit itself is simple in a sense...but the Transformer is the complex piece. There is a sample board layout in the App NOTE. I think if I lay mine out over it, the chances are it will be OK...

The stumbling block is the T

😱😱other wise U get shocked and DIE:RIP::RIP:...:crazy::crazy:

I can always build it in stages and pieces so the sum will be great.

Thanks

I have been around a while, I aint scared of the adventure the rewards are GREAT🙂
 
#1,032
well, depends on your max AC voltage you could ever put to smps, with 265Vac, that should be max voltage for 240Vac systems (If this is still true), you get pretty close to 400V anyway, and PFC voltage has to be higher then max AC voltage.

On the other hand, why not got 400v? less current, less wire, less problems. Yes you could go for only 200v, but what's the point? it's no safer then 400v, but you have less stored energy in same value of capacitor and you already ordered 450v ones, now you can use less of them for full bridge, let say one 390uF on smps, and one on PFC. since you have ordered 4, you could use 2 and 2, but as I see it, you could make 2 sets of smps+pfc

For fets, if that is what you use, irfp450 (I think), what ever I used, are rated at 500v and will have no problems with what ever voltage up to caps rated voltage of 450v
 
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#1,033
Krisfr said:
The circuit itself is simple in a sense...but the Transformer is the complex piece.
😱😱other wise U get shocked and DIE:RIP::RIP:...:crazy::crazy:
Click to expand...
1. Well complex maybe, I don't get it right every time either, but more I do and olay with them, more I know what need to be done.
2. How could you get shocked? I connect al the probes, and stand back, turn on via start up circuit, so that max current is limited to 1A for few seconds, so that none of the breakers go off, and by then circuit that is tested, should already work or show signs that something was wrong, before relay switches... then you can have full power

variac is always good to have, but I don't need it with this things, as I know it won't blow up coz of my mistake
 
#1,034
I am using IGBT's rated at 600V. So that is not a problem.

I now have a good sense of this, and I am ready to more forward another step or two.

The caps should be here this week.

I think from what I have seen Coilcraft makes those transformers for PFC based on which IC you choose. I am going to call them today to see if they have one for the way I want to go. About 400 volts at 2 to 3 amps.

TIME will tell all

Now I just have to put this full bridge IGBT into a LLC transformer setup. I wish I could find a LLC full bridge example to make sure I on the right road. your insight and direction has brought what little I know in to tighter focus.

Quick question for you, now that I think about it. How can I make a seperate output on the final stage for a lower current supply, but at a slightly higher voltage?

Like plus and minus 70 with 6 or 8 amps per rail. And plus and minus 80 with only 500ma per rail. I know it will have to be a separate winding, BUT I am not clear in my own mind how to implement it. Any suggestions?

You have been a great help to me...🙂

Thanks
 
#1,035
so are you making LLC of hard switching? I still don't know if you need to go full bridge, I don't think you will need 2kw or more of power(could be wrong)

I'm not 100% what you can do, you have few options(depends, if you need it to be floating = independent of main voltage), but I think I would try adding few more turns(depending how much one turn = volts added) to each side where that + and - 70V winding ends(for non-insulated case). Those few turns will add voltage on top of that +/-70v. I don't think you need separate winding, just winding with CT, which is not centered, but more like 70v/10v
 
#1,036
I can not get 2kw out of the wall socket anyway.

IF the ps can loaf along at 1500watts that would be great. For now I guess a 1000 or 1200 watt one would be good. I just did not want to design 2 different ones. 😀

Thanks for your patience with my ignorance of these complexities.

Thanks🙂
 
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