slideshow 250 to 5000 watts PWM DC/AC 220V Power InverterThis is my schematic design of a Pulse Width Modulator DC/AC inverter using the chip SG3524 .
I have built this design and using it as a backup to power up all my house when outages occur.
If you intend to build the circuit please vote for me so i know how many people benefit from the design, Thanks
-The schematic circuit design is for a 250 watt output, while the pics are of my 1500 watts inverter that i built, to increase the power of the circuit you have to add more of the Q7 and Q8 transistors in parallel, each pair you add will increase your power by 250 watts, ex: to get 750 watts of power from the inverter you need to add 2 of Q7 and 2 of Q8 to the original design.
--If you increase the power transistors you have to change the T1 transformer to match the new needs, the circuit's transformer is rated 25 amps to handel 250 watts of 220v, for every 1 additional amp you need on the 220v side you have to increase 10 amps on the 12v side, of course there are limits to the thickness of the winding so if you need more than 750 watts i recommend that you use a 24VDC supply instead of 12 volts:
DC voltage and Transformer "T2" winding recommendation:
12vDC up to 750 watts : 24v center tapped
24VDC up to 1500 watts : 48v center tapped
36VDC up to 2250 watts : 72v center tapped
48VDC up to 3000 watts : 96v center tapped
60VDC up to 3750 watts : 120v center tapped
72VDC up to 4500 watts : 144v center tapped
**The transformer in the pic is a (48V center tapped / 220v ) 2000 watts
--R1 is to set the PWM to 220v
--R2 is to set the frequency to 50 or 60 Hz
--Wiring should be thick enough to handle the huge amps drain from the batteries.
--A cooling fan will be needed to reduce heat off the heat sinks and transformer, i recommend getting a 220v fan and connecting it to the output transformer, when you power up the circuit the fan will start this will always give you a simple way to know that 220v is present and everything is OK..
--2 circuit breakers are recommended instead of fuses, one on the DC side and one on the AC side, depending on your design
Ex: for a 24vDC ( 1500 watts design ) put a 60Amp breaker on the DC side and a 6Amp on the AC side.
For every 1amp of 220vAC you will be draining like 8 to 10 Amps from the 12v battery, make your calculations !
-- The Heat sinks should be big enough to cool the transistors, they are seperate and should NOT touch each other. "see the pics"
- -Be cautious when building this circuit it involves high voltage which is lethal, any part you touch when the circuit is ON could give you a nasty painful jolt, specialy the heatsinks, never touch them when the circuit is on to see if the transistors are hot !! I ate it several times :)