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.
Contents
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.
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.
Edward Martin says
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..!
Swag says
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
abioye says
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
Swag says
You are most welcome abioye, please keep visiting my site, and keep up the good work
Master Mind says
Sir please explain the way you calculated power? 30*24=720 How?
Swagatam says
30 is the voltage that possibly may be used for powering the inverter and the 24 is the max current rating of the transistor.
Chinonso Ukpabi says
How many volt should i apply to the collector of that bc547 must it be 12volt?
Swagatam says
yes it must be 12V, and the trafo center tap must be separately powered with the battery positive if it's higher than 12V
Azam Higgins says
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
Swagatam says
Hi, how can a 300watt transformer produce 800 watts, sorry that's not possible.
MUHAMMED ADIO says
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
Swagatam says
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