Azfer Ahmed: asking for schematic 3kW inverter

Hello,

I found this in an e-mail from Azfar Ahmed:

Can you draw for me a complete schematic diagram of 3kw transformer circuit with 12v input, and output of 240vac? Please sir. I'm not very good in designing a circuit.

Click to expand...

As I do not give answers in e-mails I do it here.

Do you realize how many current is needed from to 12 Volts at 3 kW?
That is 3000 / 12 = 250 Ampere.
This is even in the ideal situation, the inverter will have a efficiency of about 80 - 90 %.
So the current needed is between 312.5 Ampere (for an 80%) and 278 Ampere (for an 90 %) inveter.

Bertus

That is why I stole Wookie's idea on the tag line. It seems to have helped.

Mods don't have the option of making themselves invisible as Wook and I have done, since they need to be seen (an opinion, not a fact), another idea I borrowed from Wookie.

Seems like that time of year again, people wanting inverters who don't want to give information, just demand information and leave. Maybe sometime I'll write something to spell the fact out, though it probably won't work with this personality type.

To keep this thread on track I will mention something else. Most simple inverters produce square waves. There are others that don't, but they are more complex. Square waves will not work well for many applications, the natural waveform for AC power is a sine wave. If you don't understand what I just said you really shouldn't be building your own, they can be bought cheaply (probably cheaper than the individual parts will cost) and can be dangerous to people with no training what so ever.

Here's a helpful page that has lots of ideas:
http://www.sm0vpo.com/power/psu_inverter_01.htm

Naturally, the higher power units are either commercial or adaptations of high-power UPS units.

Here is a 2KVA 12v-120v inverter that a fellow made a few years back:
http://technology.niagarac.on.ca/people/mcsele/i2k.htm
It IS possible to make something like that.

However, starting off at 12v is a rather poor choice, IMHO. One would be much better off to start with a primary of at least 24v, preferably higher, as that would greatly reduce the size of the wire required, along with peak battery currents.