Transforming a 300W Sinewave DC/AC Mini Inverter to a 5000W Monster





Introduction: Transforming a 300W Sinewave DC/AC Mini Inverter to a 5000W Monster

I was planning to build a PIC microcontroller sinewave inverter and while browsing the internet to buy the necessary items I got accross this little 300w ready made pure sinewave inverter which would cost less than all the main items I was searching.
An idea flashed in my head to try to drive my "already have" square wave inverter's power stage from this ready made thing so I went ahead and ordered it.
After receiving the item I ran some tests on it and was surprised of the many hidden options this tiny thing packed:
-Built-in PWM maintaing a stable 230v at all times.
-Over voltage "+15v" and under voltage "+11v" cutoff.
-Low battery audibale warning.
-Overload cutoff
-Waveform distortion :<5%

Actually 300w is way too much to drive the power stage, 100w would have been more than enough and the price would be much less but unfortunately I didn't find one.

Anyway.. The idea was a 100% success, I connected the mini inverter to my power stage that I already have built from a previous instructable and the monster came to life just as was expected :)

Of course you can adjust the power stage to your needs following the table of my main instructable.



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    what happened to Nick? It's a 268 volt out put. But enough of the filtering system, the power is only 168 volts.

    hello sir, i found the problem on the output transformer ... the trafo is hot like a short current, when i check the mosfet and the transformer looks fine,the voltage on "drain" mosfet is dropped when i connect to battery

    i don't understand something. i need to make a 5000w inverter. but. i need 84-0-84 + 20 transistors to get 5000w????

    i can't view any of your inverter pictures because of network problem..can someone send all me nicks inverter instructables to
    Am researching on inverter....i will appreciate anyone who send me even the author

    Hello Nick,

    I am new here and would first like to say thanks for this project of instruction. Had a few questions on the transformer useage and inputs/outputs. I am guessing that the 12-0-12 trans is rated at 220v ac input and 12v+ dc output in order to supply good current to gates? I also was wondering about the 84vdc tap trans with 220v ac out. Many may not have the means to supply 84v DC via batteries; with this being the case, can't we just use a buck converter and cap to stabilize and provide voltage to center tap? Note: transistors mention are pretty durable and I have found a few alternates to supply power to this wonderful design; ex: MJ15022, rated at 250w 16A 250v. Please assist me...

    Hey Nick,

    Thanks for the update. I will proceed with the 24 trans, any particular brand? Your recommendation is highly appreciated.


    Hi Electro46,

    It not a rule to use a 84v transformer, the power stage trans's voltage is related to the DC supply, if you're operating on 24vdc then this trans should be 24-0-24/220 and so on. Read my other instructable to get a clear idea on the transformer's power stage and what to use.

    Hi Nick,

    I have a doubt about this unit. That is when I am using the 300watt sinewave inverter, the out is connected to a 12-0-12 volt transformer. According to your table the 5kw inverter must have a 84 dc volt input. In drawing you are showing the last transformer as 84-0-84. How does this happen will the voltage automatically increase from 12 to 84 after the transistors.

    Notice at the bottom of the diagram, he has 7 12V batteries. The +84VDC comes from all 7 batteries in series.

    please refer drawing carefully ,that 7 battery's connected before 220 / 12-0-12, 0.5A transformer