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3kW Power supply. 100-240VAC input voltage

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jamesh77

New Member
Hi all,

I am looking at exploring/designing a 3kW power supply that could be used for products that are made for the US (120VAC supply) and the UK (230VAC supply). I have seen some solutions where people use massive transformers that are almost as big as the products which they are using them for.

Does anybody have any ideas or can point me in the right direction to get started?

Thanks,
 

alec_t

Well-Known Member
Most Helpful Member
Have you researched 'SMPS' ?
 

jamesh77

New Member
alec_t...yes i have researched various SMPS topologies but have struggled to find a reference circuit for something that can draw this much power.

Nigel Goodwin you have taught me something already....2KW would be fine anyway.

I am looking to design a circuit that can take an input of 100-240VAC and output 240VAC. This will be an external component that will allow me to power my home appliances/power tools from either the US or UK mains supplies. I know that mechanical timing devices and some types of motors can be affected from the different frequencies, however the appliances i wish to use this for are
 

jamesh77

New Member
Thanks Nigel, however as mentioned at top of this thread, i am not looking at using a auto-transformer.

I want to make this as small as possible, so for now cost is not an issue.
 

tcmtech

Banned
Most Helpful Member
Unfortunately the way the circuitry would work and the design for it would layout a 2 - 3 KW capable solid state universal input voltage to constant fixed output voltage unit is going to be just as big if not bigger than a common iron core transformer which if a multi-tapped unit was used in an autotransformer configuration it would only need to be 1000 - 1500 VA in actual working capacity which is not a big or expensive unit to buy or work with.

It would need an AC to DC conversion stage a variable DC to constant DC power stage followed by a DC to AC inversion stage which is not going to be any smaller than any decent quality built 2000 - 3000 watt power inverter which to be honest are physically larger and as nearly as heavy as any iron core transformer of equal power handling capabilities. More so compared to a multitap autotransformer or Variac transformer configuration.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Thanks Nigel, however as mentioned at top of this thread, i am not looking at using a auto-transformer.

I want to make this as small as possible, so for now cost is not an issue.
As we've all said, it's not a practical proposition - and if you were doing such a large project, you really need to make it specifically for one exact use, not as a general purpose replacement for a transformer.

In a current thread, SMPSU's for microwave ovens have been mentioned - these are considerably lower power than you require, cost many times the price of a transformer, are much more unreliable, and are of a similar size.
 

ronsimpson

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Most Helpful Member
I have some of these. 110/220 in 110/220 out. This picture is a small one. It is not automatic. You must switch what V in, V out.
 

crutschow

Well-Known Member
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The only way I could see to eliminate the large transformer would be to have a 2-3kW line-powered SMPS that will convert the AC to about 350Vdc.
This DC is then converted back to AC using a high power MOSFET or IGBT bridge controlled by a 60Hz modulated PWM signal.
But the cost of doing all that is going to be very high.
For example look at how complicated a 2kW SPMPS converter is, even without the bridge output.
 

RODALCO

Well-Known Member
Most US houses have a slit phase 180° supply which is 120 - 0 - 120 Volts
On the two hots there is 240 V 60 Hz available at 20 or 30 Amps, dependant on whatever MCB's are on the board.
The incoming supplies are often 100 or 200 Amps.
 

tomizett

Active Member
I'd say that it's do-able, but a very ambitious project even for someone with a lot of experience. Also, don't forget, very dangerous.
This application has a lot in common with a "double conversion" or "on line" UPS (uninterruptible power supply) - see whether you can find any information or schematics on them. I agree with crutschow on the overall topology that you'd need to adopt.
 
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