How to modify square wave to modified square wave

[engr.waqas]

How can i modify square wave to modified square wave for 220v,50HZ output.
Can someone give me circuit diagram for this or some useful links.

Thanks in advance

 

[raiya_23]

can u give some details as to what you are trying o do?

 

[engr.waqas]

Sorry 4 late response
I have designed a 24 to 220V inverter(modified square wave at 50 Hz) but i have problem when i connect my inverter to load specially fan.
When i connect fan to the inverter the voltage drops from 220 to 140 volts and fan runs very slowly and more slowly when i connect two fans.
i am not recognizing the issue.
Note that i have achieved modifying square wave.

 

[raiya_23]

What devices have you used to design the inverter? transistors? did u check their power rating?

 

[engr.waqas]

I am using Mosfets bridge using IRF640N,200V,18A

 

[raiya_23]

Have you used freewheeelnig diodes as well? if you havent maybe you should try adding them

 

[engr.waqas]

Thanks for reply
IRF640 has built in body diodes

 

[raiya_23]

The problem probably liies with the output resistance of the transistors, try using a voltage buffer