AboZakaria

why Commercial Power Inverters is Compact and Light if we try to Build Ower Own 1200Watt Converter we need a Huge 10Kgs at lest transformer to handel the 100A Current but the commercial One weight only 4Kgs and soooooo Comapct How they do this ?
Compare these
2KVA Home Made Inverter

AND
2500 Watt Commercial Inverter

Nigel Goodwin

Because commercial inverters use high frequency switch-mode techniques, not low frequency like you use.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

Brian Hoskins

That design is a decade old. The author says himself that a lot of improvements could be made with modern technology. He says that a redesign is required to modernise it.

Brian

AboZakaria

What i know aboat the inverter
12v dc -> convert it to ac using oscaltors and transistors -> transform it to 220 v ac using transformers So we need a big transformer that handel the big current (2500W Will Produce 250A) So How do they do it in commercial Inverters?

Nigel Goodwin

Try reading my previous post, high frequency means small transfomers.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

Oznog

You can't use those transformers at high freq, this generally requires custom-wound jobs. There are a lot of "critical" factors here like wire gauge, core type/size, transistor drivers, board layout, and switching freq that require careful consideration. Skin effect is a limiting factor.

So you end up losing the problem of requiring a huge transformer core and a crazy amount of copper wire, but at the same time trade it off for a whole slew of new design issues.

Larger supplies sometimes use multiple smaller transformers rather than one large one.

Note the discrepancy between "peak" and "continuous" ratings in these inverters. The output is often exaggerated.

Honestly there's no advantage to the idea of building an inverter nowadays. It would be incredibly expensive and probably wouldn't perform for crap, not the first few tries anyways. If you don't know what you're doing you could blow it up dozens of times. There's a lot of reasons to learn how to build switching power supplies though.

__________________
I thought what I'd do was I'd pretend I was one of those deaf-mutes.

AboZakaria

But the AC must be 50 or 60 hz So what they do to solve this problem and if any one have a schematic or at least block diagram for a commercial inverter

Nigel Goodwin

They either rectify it to DC, then chop it at 50/60Hz to give a simulated rough sinewave - or, on better quality units, use it as a class-D amplifier and feed a 50/60Hz sinewave through the system, removing the high frequency carrier with an LC filter (which will need a fairly large choke).

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

dknguyen

If you chopped it at 60Hz, you could only ever get a 60Hz square wave (easy and cheap, but far from ideal and large because of the low frequency). If you chop it at a higher frequency like 6000Hz with a filter and vary the duty cycle sinusoidally, you produce a sinusoid.

http://www.ece.ualberta.ca/~knight/e.../vsi/spwm.html

AboZakaria

thanks alot

HS3