Electronics > Projects, Designs, and Technical Stuff

Affordable high current PSUs?

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KaneTW:
Thanks for the replies.

BravoV: that are some really nice PSUs. I'm not too sure where to even start looking for contractors that might want to get rid of this kind of stuff, though. And, yeah, they suffer from the "companies buy this, so we can jack up the price" syndrome.

Giaime: Good idea. So basically just a dimmer on the primary with feedback from a suitable current sensor. Still would need to make a transformer, but much less of a headache.

coromonadalix:

--- Quote from: Giaime on January 25, 2019, 11:10:47 am ---
--- Quote from: KaneTW on January 25, 2019, 06:11:20 am ---2) AC power source and a transformer down to the needed region. AC power sources are expensive-ish, and a transformer for those currents is a lot of metal.

--- End quote ---

A big transformer + big diodes and capacitors, and you do all the regulation with TRIACs on the primary side. This, with some analog circuitry, could be also adopted for CV/CC/CP operation. For example output current can be measured with an Hall sensor.

--- End quote ---

A big waste of time and ressources, thoses psu are very well designed, sometimes they have pfc correction, very good line and load reglation etc ... the list goes on.

The only way to have a good regulation basis is to use toroid x-former, the bigger they get the more stable they are,  for an 1.2kw toroid you can have under 4% of drop.

With huge power smps based ones, it will be better.     We could debate a very long time over this and that ...

I used 900 to 1.2 kw  servers psu's,  with good active coling they where incredible. Had one at 5vdc 120 amps  loll  oh i have paid 254 usd for each of them.  Ebay has lots of them in many wattage and currents, you have some websites (dont recall) who tells how to mod them to suit your needs.

KaneTW:
I'm basically driving a resistive heater. The requirements aren't particularly high.

mariush:
Sounds like the VRM of a processor or video card.

Processors these days are running at 1v..1.5v and 100A+  ... video cards use even more current.

You could get a 8 phase controller and use 8 doublers to get 16 phases and that should give you what you need.

For example, this EVGA Power V  vrm for video card overclockers costs $250 : https://www.evga.com/articles/01140/evga-epower-v/

or product page link: https://www.evga.com/products/product.aspx?pn=100-UV-0600-BR

SPECIFICATIONS

    12 phase main output (0.6 - 2.0V, 600A)
    2 phase secondary output (0.6 - 2.3V, 80A)
    IR latest generation digital PWM
    Remote sense option support for vdroop compensation
    Integrated voltage monitor LED display
    Onboard EVbot MKII controls allow you to adjust voltages on the fly!
    Update your EVbot firmware and connect it via the EVbot port!
    Control your EPOWER via software by connecting a USB Type-C connector to your PC
    Dual 3-pin +12V Fan header
    1 Year, DOA Warranty (no exceptions)

It may be possible to tweak it to get more than 2v on the main output.

Doctorandus_P:
A TIG welder seems like a logical choice to me.

Tig Welders have an ouput of usually between 20V and 30V (Max ratings probably betweeen 15 to 40?)

These will not work unmodified, but they will contain almost all the hardware you need. They have a powerfull SMPS with isolation between primary and secundary, Power electronics for switching, auxilary power supply for the electronics / displays, a case to contain everything, Cables & connectors etc. And you can get such a thing for < EUR 100.

When you open such a thing It could even be that you find something like a TL494 or other commonly uses SMPS chip inside.
It seems unlikely that 2kW of power is switched by a single chip design. A regulator chip with external power switches is far more likely, especially by the cheap brands.

With expensive brands you might find fully potted PCB's or module's.

There must be plenty of tearowns of these on Youtube. It could be worth to watch some to find a model that is easy to modify.

Also:
You have to be aware that these welders are never capable of delivering the full current continuously.
They always have an ED rating, and this can be as low as 20% for the full current.
ED of 20% means you can only use it 20% of the time (at that specified current) during a 15 minutes (or half an hour?) period.

So when modding, you might consider adding bigger heat sinks, fans and temperature sensors / cutoff's.
Even skottky diodes easily go over 1V @400A, so that is already over 400W you have to dissipate  ( Unless you have a synchronous rectifier).

Make sure that the versions you get are capable of outputting DC. Some may only do AC.

But doing such a mod can easily consume a few day's worth of time, with no guaranteed result.

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