Inverter problems

[daGenie]

The inverter I built does not produced the proper output voltage of 220 volts, 50 Hz, but 154 volts ac and then starts to drop. The transformer also starts to heat up after some minutes. Does anyone have an idea on how to solve this problem. All answers would be highly appreciated.

 

[GonzoEngineer]

If the transformer heats up, you ar either saturating it, or you have a lot of ringing.

 

[daGenie]

How do I solve the problem?

 

[duke37]

Show a circuit diagram of the inverter so that we can see what you have.

If the voltage is reducing, is the power supply holding up?

 

[daGenie]

The power supply is stable at 12 volts.............the diagram is not really available 'til I can find a scanner. I can't remember the website I got it from. Everything appears to be right though.

 

[(*steve*)]

First thing -- assuming your input voltage is 12V, are you using a 220V to 12V transformer as a step-up transformer?

If so, you have 2 problems. The first is that there is some inefficiencies, so a 220 to 12V transformer used the other way will produce only (say) 200V -- however you'll notice this mostly under load. The second is that the peak voltage of 12V AC is almost 17 volts, so if you are switching a 12V source to a 12V winding, you're effectively providing (probably) a lower voltage.

The latter effect would give to approximately 155V. The former effect may be the cause of the voltage falling further under load.

The heating may be caused by your load. What is the transformer rated at, and what is your load? (I suspect you're using a simple square wave too, and that certainly won't help).

 

[Rleo6965]

If the transformer heats up, you ar either saturating it, or you have a lot of ringing.

How do I solve the problem?

Try using higher wattage iron core transforner.

 

[daGenie]

Thank u all, i am going to try out all your suggestions

 

[daGenie]

The inverter is actually working now. Thank you steve, all your suggestions made a whole lot of sense.
I've have 2 questions now:
Why does the transformer make noise only when there is no load?
Secondly, how do i change the output from a modified square wave to a sine wave?
Once again, any suggestion would be appreciated. Thank you all in advance!