Making a nearly 2kW power supply

[TechGuy]

This company will build you a custom toriod 60hz AC Transformer for you for a very reasonable cost. They do custom transformers from 23VA to 12KVA.

Custom Design Toroidal Transformers

[harryz33]

True, it would need some radical form of cooling. I guess designing and making an SMPS would be a good idea (still a tad dangerous) or perhaps the SMPS from a car amp? Though a 2kW one would be difficult/expensive to find, let alone one that outputs 48VDC (or around 40VAC - I'm guestimating the numbers)

[kevinkr]

Originally Posted by ahmelsayed

OK. is there any way to regulate the output of a rectifier bridge ?

There are a variety of ways involving power mosfets, SCRs, etc., but they are complex and expensive to implement. (They essentially replace two elements in the bridge)

You'd be better off purchasing a proper supply for this application, the power levels are appreciable and if you need voltage regulation the challenges are considerable. Not to mention the very real safety issues at these power levels.

If you are running 48V switching power supplies off of this supply it does not need to be regulated as long as the output voltage does not drop below or exceed the input range of the switcher.

[sawreyrw]

If you have never built a linear power supply before, you should build something much smaller to get some experience.

Here are some hints.
1. A linear regulator is very inefficient. This means you will have a huge power loss and a major thermal problem.
2. Learn about heat sinks and cooling.
3. You will most likely need several pass transistor in parallel. Learn how to effectively parallel power transistors. Use emitter or source resistors.
4. Provide shor circuit protection and make sure the power devices can handle the heat. Consider foldback current limiting.

Geez, even though I have a lot of experience with this type of thing and "automatically do what I advised, I didn't appreciate how much effort it is. No, it is not simple.

[Mark Allen]

Thats one you would no doubt want to operate on 240 volts primary to make it more efficient. That is if you are in the USA...

Mark

[harryz33]

So what about something like this? 48 Volt AC/DC Power Supplies, High Power, 330 to 3200 watts, Chassis and Enclosed Pretty pricey, but I don't know how much it would be to build one so . .

[johansen]

wasn't there a thread the other day about a 48 volt ~20 amp smps that could be found on ebay for less than $100? I can't recall the partnumber but i did search ebay for it and there were plenty to be found.
HP384779-001 Power Supply 48 Volts Hot-Swap 1U | eBay
^that's not it but it is a lot cheaper than a 50 pound transformer... 5 pounds of capacitors and a heatsink the size of a toaster....

FYI: I have two keptco 0-36v 0-30 amp units that are just as overbuilt as their quarter rack units.
The transformer is as big as the tx in a Lincoln 225 amp welder.
There are 18 TO-3 transistors paralleled on two separate heatsinks, each group of nine had .3 ohm emitter resistors and the two groups were paralleled though a wad of nichrome wire...

Today you can fit the same supply inside a package the size of the capacitors used to filter the 60hz transformer. (which would be easy considering there were 4 of them, each the size of a 12 oz beer can.

[Tony]

Originally Posted by ahmelsayed

Hello, Everyone

I'm trying to build a power supply that is nearly 2kW which supplies 48 Vdc and 40A. - I know it is high power but i want to build it at home -
so please, is there any suggestions ??

Thanks in advance

2kw load implies that you need a traffo with about 3kva capacity.....

you may also consider 4 12 volt car batteries and a charger combo so that what you have becomes a UPS setup..

[harryz33]

you may also consider 4 12 volt car batteries and a charger combo so that what you have becomes a UPS setup..

This is what I do, I have a 12Ah battery powering a car amplifier, and I just leave a float charger on the batteries most of the time.

[TechGuy]

Originally Posted by harryz33

So what about something like this? 48 Volt AC/DC Power Supplies, High Power, 330 to 3200 watts, Chassis and Enclosed Pretty pricey, but I don't know how much it would be to build one so . .

Those prices are reasonable. They include PFC (power factor correction) and have electronic fuses to shutoff the output in an overload condition. You will not be able to build something cheaper on your own. Perhaps going with a unregulated Linear power supply, you could cut the cost by $100-$150.