4KW EE65 Transformer

[mag]

Check out that beast:

Meanwell Power Supply Products

This is a 24V 125A (3kW) power supply. It runs in phase shift with current doubler.

The transformer is, believe me or not, a small E42 core...
The fan cooling is huge so that it makes possible to use a smaller core.
If you can accept an higher temperature rise of the transformer or if you use
strong forced air cooling you will be able to pass much more power from the transformer.

ETD59 or even better EE65 can pass much more than 3kW continuous if forced air cooled.

[microsim444]

Originally Posted by mag

Check out that beast:

Meanwell Power Supply Products

This is a 24V 125A (3kW) power supply. It runs in phase shift with current doubler.

The transformer is, believe me or not, a small E42 core...
The fan cooling is huge so that it makes possible to use a smaller core.
If you can accept an higher temperature rise of the transformer or if you use
strong forced air cooling you will be able to pass much more power from the transformer.

ETD59 or even better EE65 can pass much more than 3kW continuous if forced air cooled.

I totally Agree with you, EVEN ETD49 is capable of delivering 4KW running at 500KHZ resonant, then its possible,

savure point of view is running ETD49 at 60Khz to get 3KW!!!

Thats all!

[megajocke]

Where did you get 500kHz from? The datasheet for the Meanwell says 100kHz. Also, 3kW from an ETD49 at 60kHz isn't as impossible as you'd think with forced air cooling, good windings and a low-loss core material.

Did you take proximity effect into account when you designed the windings of your transformer or not? If not, then you'll have high losses for sure.

mag: Do you know if the Meanwell runs at 100kHz transformer frequency or 50kHz? The datasheet says fosc = 100kHz and that can sometimes mean 50kHz transformer frequency, but for a E42 at 3kW, that sounds low, even with really good air cooling.

[mag]

Hi Megajocke,
the oscillator is running at 200kHz so the transformer is at 100kHz.

BTW it is not at E42, the current doubler inductances are wound on E42.
The transfomer is an ETD49.
I don't think that at those frequencies the core material is important. If you check a standard 3C90 core or a low loss 3C92 core they exhibit similar losses at 100kHz. It is just a matter of cooling.

The windings seems to be made of litz wire to reduce Rac/Rdc ratio.

@microsim:
take care about proximity effect. It is a killer effect at those power levels.
In my first transfomer prototype of a 24V/100A SMPS I was using for the secondary 5 turns of copper foil of 0.5mm thickness. The copper foil was og the same length of the coil former so that it was a 5 layer winding.
The transformer was at around 130°C with only 20A loading... After taking the proximity effect into account I calculated a current density in the secondary of around 150A/mm^2 instead of my 4A/mm^2 due only to skin effect. After having rewound the secondary with 6x litz wires of 240x0.1mm everything stays cool...

I suggest you to don't use more than 2 layer copper foil.

[microsim444]

Originally Posted by mag

Hi Megajocke,
the oscillator is running at 200kHz so the transformer is at 100kHz.

BTW it is not at E42, the current doubler inductances are wound on E42.
The transfomer is an ETD49.
I don't think that at those frequencies the core material is important. If you check a standard 3C90 core or a low loss 3C92 core they exhibit similar losses at 100kHz. It is just a matter of cooling.

The windings seems to be made of litz wire to reduce Rac/Rdc ratio.
@microsim:
take care about proximity effect. It is a killer effect at those power levels.
In my first transfomer prototype of a 24V/100A SMPS I was using for the secondary 5 turns of copper foil of 0.5mm thickness. The copper foil was og the same length of the coil former so that it was a 5 layer winding.
The transformer was at around 130°C with only 20A loading... After taking the proximity effect into account I calculated a current density in the secondary of around 150A/mm^2 instead of my 4A/mm^2 due only to skin effect. After having rewound the secondary with 6x litz wires of 240x0.1mm everything stays cool...

I suggest you to don't use more than 2 layer copper foil.

Mag.

Thanks for the informations, My 4KW transformer was made at specialist Transformers manufacturer in the USA, and its Calculated to handle that power correctly, also its foil windings, carfully manufacturered to deliver the power I need, EE65 with 30C90 material.
I think per there calculations, it wont hit 60C at 2KW RMS Load. cant remember exactlly.


Thanks.

Fox

[megajocke]

I wonder how high one dares push the core losses in an ETD core with forced air cooling... The point where the center legs meet doesn't have that good cooling.

I was thinking of core materials similar to this:
http://www.ferroxcube.com/prod/assets/3c96.pdf
100°C, 100kHz 100mT losses are half of 3C90, 40 instead of 80 kW/m³ (1,0W vs 1,9W for ETD49)
100°C, 100kHz 200mT losses are 35% lower than 3C90, 300 instead of 450 kW/m³ (7,2W vs 10,8W for ETD49)

for reference:
http://www.ferroxcube.com/prod/assets/3c90.pdf

[gearheaddruid]

Just got this today, bought it off Ebay for $30.00! It is new, in the original box.
Output rated at: 27 volts, 145 amps! Phase shifted IGBT power stage, three W20nb50 IGBTs per leg. I will post more info as I have time to do more reverse engineering. There are two toroid cores stacked inside the windings. They are about 2 inches diameter and 7/8 inches tall each.
This has another part that is a power factor correction supply with an output of 400 volts. It's toroid is even smaller. I have removed the heat sinks to take the pictures. The whole thing was in a nice square box with forced air cooling.

[megajocke]

How do they manage to get good enough primary-secondary insulation? Has it something to do with that white wire perhaps? It is unusal seeing toroidal transformers in offline SMPSs.

[gearheaddruid]

Megajocke, the primary is made of insulated wires, (the white ones) There are about twenty of them in parallel. The secondary is enameled wire. I was surprised to find the toroid also. It makes it a lot easier to rewind than an epoxied etd or ee core. Not sure what I am going to rewind it for yet. It would make a killer supply for a big amp. If I was still doing car audio, it would make a nice 300 amp 12 volt supply for testing.

[kall]

i borrow this thread for my question, i really hope u guys and girls have a solution to my problem....i hope its okey.

i want to build a transformer but i cant find a suitable core for my calculated values....

here is some data:
n: 20/1
P: 2.5kW
f: 100kHz
I1rms ~ 7A
I2rms: ~ 115A

the thing is, i want to use a UU, UI core, and with U93 from ferroxcube i get a flux at 10mT .... im basically not using the core at all

if i go down in size, the windings wont fit because i need atleast n1 to be 40 turns due to the large turnsratio of 20 to 1 ....

am i thinking wrong??, i think u experienced builders have a solution to this....