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Thanks E-Design, this is starting to make sense. I will wait for next results and post any final questions then.
Skin depth at 100 Khz is only 0.2mm.
https://chemandy.com/calculators/skin-effect-calculator.htm
Thickest wire or foil should only be 0.4mm max.
Anything thicker just takes up space and does nothing.
E-Design, this is important you should use the same winding width as the OP has.
ferroxcube = 41.2mm total winding width of bobbin.
Also if you have time can you run two designs, one with foil primary and one with primary made up of magnet wire.
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usama14, i am worried about skin depth with your method. I have time to think about it now.
Yesterday we did not take in account efficiency. Just picking a number of 80% we get.
1kw/.8 = 1250W
1250w / 39vdc = 32A
Now the skin effect will be even worse, we need even thicker wire. The rule of thumb is start with 500 circular mils per amp.
500 Cmils/A x 32A = 16,000 Circular mils.
Looking at the chart i gave you in post 31 that is 8 awg wire. This project is going from bad to worse.
I think warpspeed nailed it when he said use copper foil, but even the .008" foil is a little light, .010" may be needed.
Ten thou foil should be fine.
Either different number of windings or incorrect measurement.
The "bundle of wires" primary winding method does work, but it is very inefficient of space on the bobbin. It produces an ugly lumpy winding which is not very nice to place another winding on top of.
The trick to winding (designing) these transformers is to use the very limited winding space available on the bobbin as efficiently as possible with the maximum amount of copper, bearing in mind insulation and skin effect requirements.
I might suggest you go ahead as intended, get it up and running, and do some testing and measuring, design a suitable choke, and test the feedback loop for stability and response. There is still plenty of work ahead.
At that point, you may decide to slightly adjust the number of secondary turns.
That would also offer a good opportunity to rewind the primary with foil.
O.K., how did you measure the inductance?No. I am positive that I gave correct number of turns
What material did you end up using, 3C90, 3C94, or 3C95?
If your E cores are damaged or contaminated surfaces, then your inductance will be low.
YOu can try burnish lapping on glass in an elliptical pattern with very fine compound or very very fine wet-dry sand paper with something to hold it co-planar at all times.
Surface roughness in microinches.....
Then clean and clamp properly.
Did you measure near 100kHz? and SRF?
I would have to say yes.
The small extra introduced air gap will make a significant difference to the inductance.
But in this application it will not matter.
Go ahead with testing your prototype.