Using a large 60hz toroid transformer as an SMPS transformer

[EWorkshop1708]

Has anyone here used the toroidal core from a 60hz mains transformer as a really large core for a High Frequency, high power SMPS transformer before???

I figure if you unwrap all the old wire coils from the toroid transformer and get the bare core, then you can wrap your own thick coil wire with the amount of turns you like, as thick of wire as you like, and get a very powerful SMPS because BIG CORES are hard to get for SMPS.

What's your take on this? Has anyone tried this? I'm thinking of getting small 30VA - 500VA toroid transformers, and rewinding them with thicker wire of fewer turns for a high power SMPS core to get well over 1-2KW.

It may prove good for really high power SMPS for insane car audio amplifier for anyone here who likes DIY high wattage!!!

Anyone tried it before? I'm considering getting a small toroid to get a 3,4,5, 6 or more inch toroid core for SMPS.

[Andy5112405]

50/60Hz transformers use an iron cored transformers.
SMPS transformers use ferrite cored transformers.

I imagine that the hysteresis of iron would be far too great for the transformer to work effectively at high frequency.

[luka]

you could use it, but with bit higher freq. I don't think you could drive it with 1000Hz

[Andy5112405]

Originally Posted by luka

you could use it, but with bit higher freq. I don't think you could drive it with 1000Hz

Most SMPS designs run in the 10s of KHz (50KHz is pretty typical).

[dragonxwas]

^^ +1..

for an smps to work properly at HF it needs a ferrite core transformer, then you would have to get into detail what grade of ferrite is good for the frequency you use and so on..

So designing a SMPS is a bit complicated, but then if its car audio you want to use it for, why not use multiple easily available small transformers ?

Say each providing power for 2 channels ?

[Urgon]

AVE...

Iron core won't work in SMPS design. It will saturate with magnetic field quickly and on the output you won't get much power. It will also get very, very hot. Like a piece of iron in induction heater...

It's better to get ferrite core, even those from old PC PSU's can give you 300-400 watts with no problem. The biggest core I've seen was only twice the size of the core from PSU and the SMPS in which it was used gave out up to 1,3kW...

You must remember that typical switching frequency is 20-150kHz and it's square wave. Iron cores don't like it. However you can build a sine wave generator rated at 50-100Hz and use it with your transformer to form full-bridge SMPS...

[luka]

Originally Posted by Andy5112405

Most SMPS designs run in the 10s of KHz (50KHz is pretty typical).

well yes, but it could at any you would like, SMPS doesn't mean it can't work at 10Hz or at 1000MHz
While he asked for 60Hz trafo, that can't work in kHz range, but could in some 100Hz range

[hesener]

If you want to use it at 400Hz or 1kHz or so, you may not even have to rewind it.... most toroids have a pretty good (well, .....) frequency response that should be good enough to improve power transfer and make the power supply smaller.

that reduces the challenge to building a class-D power amplifier with 230Vac output at some kW.... nobody said it was going to be easy.....

just my two cents

[Andy5112405]

The original thread asked would the iron transformer be any good at High Frequency.

[luka]

Originally Posted by Andy5112405

The original thread asked would the iron transformer be any good at High Frequency.

yes, but what is high freq? some could say 400Hz is high, compared to 50 or 60