High power (50A 2nd) 500V:50V hi freq (100s KHz) transformer

Thread Starter

vleo

Joined Sep 9, 2012
2
I'm working on a DC/DC converter (power supply) that has to go from 500V DC to 50V DC.

What would be a place to start for designing transformer for it - what kind of core material and shape to use for best efficiency - what frequencies are better 50KHz or 200 KHz or 500 KHz or more?

It seems that prebuilt transformers like that are not on the market - i.e. DigiKey does not yield anything useful.

On top of all other requirements - it has to be very FLAT - no more then 25-30 mm.

I understand that I'm looking for a kind of Holy Grail of SPSUs, but still dare to ask :)

p.s. if this is the wrong forum would love to be directed to the right one for such a question
 

Papabravo

Joined Feb 24, 2006
12,384
Transformers don't work on DC, they only work on AC. I'm curious about the source of 500V DC, what is it?

I suppose you could convert the 500 VDC to AC. Then use a transformer to drop the AC voltage and then convert it back to DC. I'd be surprised if this process was 50% efficient.

You might be better off using the 500 VDC to run a DC motor connected to an AC generator. The output of the AC generator can be transformed, rectified and converted to your 50 VDC. Whatever you do is going to cost a small fortune.
 

kubeek

Joined Sep 20, 2005
5,598
I suppose you could convert the 500 VDC to AC. Then use a transformer to drop the AC voltage and then convert it back to DC. I'd be surprised if this process was 50% efficient.
That sounds like a smps, and with a properly designed one you should be able to achieve at least 85% efficiency.

To the OP, the big quiestion is what sort of power or current do you expect from this transformation?
You can get HF transformers that are even thinner than 30mm, but they usually compensate by being wider and longer.
 

Thread Starter

vleo

Joined Sep 9, 2012
2
Transformers don't work on DC, they only work on AC. I'm curious about the source of 500V DC, what is it?

I suppose you could convert the 500 VDC to AC. Then use a transformer to drop the AC voltage and then convert it back to DC. I'd be surprised if this process was 50% efficient.

You might be better off using the 500 VDC to run a DC motor connected to an AC generator. The output of the AC generator can be transformed, rectified and converted to your 50 VDC. Whatever you do is going to cost a small fortune.
I will not use transformer on DC - but DC/DC converter basic outline is - DC - switch to turn DC to AC - impulse transformer - AC/DC rectifier

510V DC is what 3-phase 380V turns into after full-wave rectification.

To
kubeek

Speaking of power - it has to be about 600W, i.e. about 15A on 2nd-ary - yes, seems that transformer has to be rather flat

To:
Dodgydave

Thank you, asked them for advice and quote.
 
Last edited:

R!f@@

Joined Apr 2, 2009
9,647
Every now and then there comes these guys !....

What are they learning in school ? Friggin ABC ?
 

Papabravo

Joined Feb 24, 2006
12,384
That sounds like a smps, and with a properly designed one you should be able to achieve at least 85% efficiency.

To the OP, the big quiestion is what sort of power or current do you expect from this transformation?
You can get HF transformers that are even thinner than 30mm, but they usually compensate by being wider and longer.
Doing so at those current and voltage ranges will be difficult. Saturating your inductors will kill your efficiency.

@vleo
BTW -- how can you say you are not using a transformer, then say "impulse transformer". A transformer is a transformer.

It would be easier to use the transformer on the AC mains to get to more reasonable voltage before rectification and filtering. A plain flat iron transformer is what you want.
 

vk6zgo

Joined Jul 21, 2012
677
I will not use transformer on DC - but DC/DC converter basic outline is - DC - switch to turn DC to AC - impulse transformer - AC/DC rectifier

510V DC is what 3-phase 380V turns into after full-wave rectification.

To
kubeek

Speaking of power - it has to be about 600W, i.e. about 15A on 2nd-ary - yes, seems that transformer has to be rather flat

To:
Dodgydave

Thank you, asked them for advice and quote.
For 15A at 50V,it is 750 watts.

You could buy a single phase commercial 50V supply which could do that,& probably would fit into your size limitations.

Why are you using 3phase?

OK,it is more efficient at quite high powers,(well above 750W),but is almost always harder to do,& more bulky.
 
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