Here we learn about a couple of simple circuit configurations which will convert any low power inverter to a massive high power inverter circuit.
You'll find a plenty of small and medium sized inverters in the market ranging from 100 to 500 watts, the same may be seen posted in this blog. Upgrading or converting such small or medium power inverters into massive high power inverter in the order of kvas may look quite a daunting and complex, but actually it's not.
Analyzing Inverter Topologies
All inverter topologies basically incorporate an oscillator frequency which is then amplified using power devices to high current levels before dumping into the step-up transformer for the final voltage boosting procedures.
The current amplifier stage which employs high current devices is where the upgrade needs to be done in order to achieve any desired power outputs from an inverter.
The modern day inveters heavily rely on mosfets for the above mentioned power conversion stage, nevertheless BJTs can be also used for the same very effectively, in fact much reliably than mosfets...
How to Upgrade Low Power to High Power
The following diagram shows a simple and very effective power output stage which can be integrated with any totem pole IC outputs such as IC 4047, IC TL494, IC SG3525, IC 4017 (clocked with IC555), for acquiring upto 1.5kva conversions.
The key devices in the circuit are the combination of the TIP122 and TIP35 which become a high gain, high current transistor pair, capable of boosting current to the rated massive levels instantly.
Each such device module is rated to produce at least 30 x 24 = 720 watts, so by adding more such modules in parallel any desired kva range can be anticipated from the configuration
Using Power BJTs
Using BJTs could be very reliable and simpler but quiet bulky, if space is your problem and need the upgrade from low to high power inverter in the most compact way, then mosfets becomes the popular choice and may be wired as shown in the following diagram:
The input is derived again from any totem pole IC outputs, the MOSFETs could be rated as per the desired upgrade from lower to the highest magnitudes.
The diode integration suggests a simple PWM insertion which is optional, but could be used if a modified sine wave output intended to be included in the upgrade.
Adding MOSFETs in Parallel
The above explained ideas for upgrading a low power inverer circuit to a higher power version can be implemented to any desired level, simply by adding several MOSFETs in parallel.
Adding MOSFETs in parallel is actually easier than adding BJT in parallel. It's just about connecting the all the drains, and all the sources together, and then joining all the gates together through individual 10 ohms resistors.
Upgrading Transformer and the Battery
MOSFETs are like switches, which means that only by upgrading the MOSFETs will only bolster the switching part to handle higher wattage and current. However, to actually achieve the desired high output wattage, the transformer and the battery rating will also need to be upgraded accordingly.
For example, if the a 100 watt inverter is upgraded to 500 watts, then the along with the MOSFETs, the battery Ah and the transformer wattage will also need to be increased to the interned 3 times or higher values.
The above explained simple strategies would be enough to enable you to upgrade, or modify, or convert any small or low power inverter design into a high power inverter circuit with the desired wattage specs.
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Sir! <thank you for your excellent site 🙂
I hope you can help me, I have a bunch of 230/12V 23A transformers, I'm planning to use 3 in parallel to make a 900W inverter based on your 500W inverter design. Unfortunately the transformers don't have a mid tap, they are 2 wire. I also have a bunch of IXQT13N10P, can I use them in parallel? If not, I do have some K2837 and some IRF3205PBF, can I use any (or some?) of these in combination or parallel to archive my goal? I'm planning to use a 24V battery bank of lead-acid batteries consisting of equal 12V batteries in series/paralell (or would 12V be easier)?
Hello Karstein, yes paralleling may be possible but only at the primary side, not on the 220V side. Before that try with a single transformer to confirm the working, using the following concept:
Simplest Full Bridge Inverter Circuit
The MOSFeT should be exactly as suggested in the above link, other FETs can be tried if they have exactly matching specs.
Good day sir..Engr. There is a foreign inverter Ferrite core transformer…the out high voltage 310VDC complete, but the switching system, for load regulator is not working, please can you help with a circuit that could switch the MOSFET at the out put stage….please help me….
Thanks
Hi Sunshine, if you referring to the oscillator section, then probably you can use the IC 4047. Adjust its output to 100 kHz, feed the frequency to the MOSFETs, then gradually reduce it until you get the most optimal result from the inverter.
Hi
I want to built 3.5kva 48v to 2220v sinewave inverter can you assist with the part lis and cicuirts board
You will need a 80 amp 48 V transformer….many IRF3205 mosfets an the IC 4047 oscillator circuit.
the basic design will be as given below:
500 Watt Inverter Circuit with Battery Charger
sir. i have a 200w inverter which is not design with ics. so pls sir can u explain how i can connect it with the above circuit. cos i see its connected to the ICS here.. am still a fresher in electronics though
Olatunji, if you are already having a fully working inverter then you can simply check the output power devices and replace them with more powerful devices. No need of making the improvements suggested in the above article.
I am sure your inverter would be using mosfets for the power devices, you just have locate them and replace them with more powerful mosfets, as per your desired specifications.
And yes, this would work only if your transformer and battery are also accordingly upgraded.
I tried to post my question but it seems like it didn’t post.
Dear please provide me a circuit which can be used after my 150v DC smps to control/vary voltage and limit current….volt/current adjustable.
Thank you..!
You can try the following circuit,
https://www.homemade-circuits.com/0-300v-variable-voltage-current/
ignore and eliminate everything that’s on left side of C1
sir please how can i connect a relay in the inverter so that it can automatically switch to the mains when the mains is on,and ratings of the relay. 200w inverter
olatunji, you can follow the following concept
https://www.homemade-circuits.com/how-to-convert-inverter-to-ups/
sir i wish we have a kind and honest person like you in our country to enlighten novice like me in my country too
All thanks to your quick and fast reply i am able to turn my small ups into a 3000watt pure sine wave inverter within two weeks i pray the lord shall always strengthen you to continue the good work of yours
sir i nose around for months but your site is the king of site sir i mean the best i wish more people like you will stand up to enlight
more people like me thanks
You are most welcome abioye, please keep visiting my site, and keep up the good work
Sir please explain the way you calculated power? 30*24=720 How?
30 is the voltage that possibly may be used for powering the inverter and the 24 is the max current rating of the transistor.
How many volt should i apply to the collector of that bc547 must it be 12volt?
yes it must be 12V, and the trafo center tap must be separately powered with the battery positive if it's higher than 12V
Hi if I was to use you circuit as stated above would the original transformer in the 300w inverter work of I was to modify it to plus minus 800w
Hi, how can a 300watt transformer produce 800 watts, sorry that's not possible.
good day sir, i so much appreciate all your work in this blog, may God continue to guide you. please i need a complete circuit diagram for 1.2 KVa pure or modified sine wave inverter with inbuilt charging section.
thanks
thanks Muhammed, just integrate a 4047 oscillator circuit with the mosfet power stage as explained above, you would be able to achieve the required specs instantly
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