hi.
can any body help me to upgrade inverter circuit diagram of 500w as i m interested in to use for 2000w.
thanks

Attached Images

12 to 220 invertor.gif (16.0 KB, 42 views)

 

That inverter circuit does not work:
1) Its lower driver transistor is shorted.
2) The 2N3055 has a very poor max saturation voltage at 10A and is worse at higher currents so the max output power is 20A x 12V= 240W, not 500W as shown.
3) The circuit does not have any protection diodes.
4) The resistor in the oscillator is only 100 ohms. Texas Instruments recommends a minimum value of 10k ohms.
5) The capacitor in the oscillator has a value that is way too large. It is so large that a non-polar capacitor will be huge and expensive.
6) It uses two quad opamps instead of one LM358 dual opamp.

I helped fix it a few years ago but a circuit with Mosfets is much better.

Attached Images

500Watts_Inverter.gif (58.2 KB, 31 views)

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Uncle $crooge

 

Before going too far, you should try to find a transformer with a 12-0-12 rating of 200A. It will need to be wound with at least 12 mm diameter wire or larger. All 12V connections must use 12 mm wire, and need to be as short as possible.

If you find that, then look for a battery with a 250A continuous output. If you use a "heavy duty" auto battery (55 AH), it would be flat in 5 minutes but it will probably explode before then.

 

a 12-0-12V transformer is useless anyway because the peak output voltage will only be 220V which is 155V RMS which will drop even more under load. To get the required peak voltage, you need a 9-0-9V mains transformer with extra turns on the secondary to provide the full voltage at the full load.

If you want a 2kW inverter, increase the supply voltage to 48V and use a 30-0-30V mains transformer which will give a high enough peak voltage at full load.

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I was thinking about that, too. A square wave as shown by OP is a bad idea anyway, because RMS voltage is pretty close to peak voltage. This may be pretty good for rectified loads such as a PC, but resistive loads like lamps get twice their rated power!

 

The peak voltage from a square-wave provides the same amount of power to a resistive load as the RMS voltage of a sine-wave. But the peak voltage of a square-wave is too low for most electonic items whose rectifier charges the main filter capacitor to a voltage very close to the peak.

So many inverters produce a "modified sine-wave" that is a square-wave with two steps in it. The peak voltage of the steps is almost the same as a sine-wave.

Here is a graph of a modified 120V sine-wave:

Attached Images

Modified sine-wave.PNG (22.1 KB, 10 views)

__________________
Uncle $crooge

 

Was it that long ago?
http://www.aaroncake.net/forum/topic...97&whichpage=3
Of course the better design would be a DC-DC convertor running at a few hundred Khz and then chopping the high voltage DC back into AC. It would make the transformer much lighter than the 2KW 50Hz monster required by these simpler circuits. Myself, I'd just buy a 3KW one at Canadian Tire for $500 and be done with it, but I only need 115Vac. Certainly cheaper than trying to find a 3KW 60Hz transformer!
Some 220V ones:
http://www.litewave.co.uk/limousine_inverters.asp

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Did you really base something on an Aaron Cake design

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Bill
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Aaron Cake says that he did not design and did not even test most of the projects on his site.

We talk about Mosfet inverters in his forum.

__________________
Uncle $crooge

 

You get round that by reducing the duty cycle; i.e. building a modified sinewave inverter so the peak voltage will be 330V and the RMS voltage will be 230V. That way both rectified and resistive loads will be happy.

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