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How to Convert 3 phase AC to Single phase AC

The post discusses how to convert 3 phase AC to single phase AC through a special bridge rectifier at any desired voltage. The idea was requested by Mr. Chaquito

Technical Specifications

You have a very nice page and I find it really good, If been looking for a 380V 3ph converter to 230V, it should with held at least 3-5 KVA. Not sure if you have one or
would you be able to direct me to one.

I have a 3ph input of 5.5KVA from a generator that I would like to convert to one single output of 230V +- 3-5 KVA. Doing the usual ph to neutral per ph would not give me a strong KW output. Transformers are very expensive.

I would appreciate your help thank you.


The Design

The question how to convert 3 phase AC to single phase AC can be solved by first rectifying the 3 phase AC to DC and then converting the DC back to 220 V AC through a full bridge driver IC and H-bridge mosfet network.

The first stage intended for converting the 3 phase AC to DC may be executed simply by the traditional diode bridge network, as may be witnessed in the following diagram. After filtration this would produce a peak of 530 V (with a filter capacitor of around 10uF/1kv included across the load)

Now, once the 3 phase rectified DC is achieved, this will need to be converted to the desired single phase AC, as per the request this value should be 220 V.

A full bridge mosfet driver topology may be incorporated for implementing the above requirement, as shown in the following diagram:

The layout looks simple and easy to configure, however it would produce and subject the load to the full 530 V instead of the specified 220 V.

The issue can be normalized and controlled to the desired levels through an external voltage sensor circuit, which could be further integrated with the Ct pin of the IC IRS2453.

The simple solution can be implemented by incorporating the following circuit:

The 220k preset is adjusted precisely so that the transistor just begins conducting at voltages around 240 V across the load.

When the transistor conducts, the Ct pin is grounded at that instant, forcing the IC to inhibit its oscillations which in turn renders the high side outputs to go low, cutting off the rectified high voltage to the mosfets.

This results in lowering down of the voltage across the load which allows the BC547 to switch OFF and restore the IC operations....the procedure repeats making sure that the output stays under control and at the specified 220 V level.

Need Help? Please leave a comment, I'll get back soon with a reply!


  1. Dear sir,
    I Want AC zero crossing voltage detection. positive halfe cycle out one puls and negative half cycle out one pulse. Both pulse width is depend on control voltage. I found two IC. Uaa145 and TCA785.both IC's are too cost. Is possible please share the circuit.mail:


  2. Dear suresh, not exact but a similar design may be seen in the following article:

    VR1 determines the pulse width of the AC cycles across the connected load.

  3. Hey Swag, congratulations for the blog, is very educated, checking at the above circuit, it cross my mind (with some stuff got from some bad credit/payment clients) if I have 3 inverters truly sine-wave, same brand, same model, same output 1500w at 120vac, all 3 getting power from the same battery bank, can I connect all 3 output in this above circuit ( 3 phase AC source) and get after a 4500w at 120vac? am I craze or that can be possible!!! I understanding because the above circuit was made with MOSFET so it might loose the truly sine-wave, but that could be fixed right? take you time think about and please let me know your thoughts. God bless you for your hard work, thank you MIARIVER.

  4. Thanks Mariver,
    yes that will be feasible but the outputs of each inverter will need separate bridge networks, so that the inverter outputs get connected across the bridges without messing up with each other. The outputs (+/-) from each bridge could then be tied up and integrated with the full bridge driver circuit as shown in the second figure above for getting the intended combined power from the three inverters..

  5. Hey Swag, first thanks for keep publishing this blog is very help full, I have a question and I don't know if this is the right section!!! sorry for any inconvenient.
    I am working from my car, running: a laser copier/printer, a die sublimation photo printer, a note book, 2 cellphones, and plus plus.
    My inverter is (1500w 12dc-Battery in to 120ac out) a very good one.
    after 4 hours of working the battery is getting too low, so the inverter starting to run on protection mode and beeping like craze. So I decide to run a 6-pack of super capacitor in parallel with the battery to support the (peak moments) the problem is the super capacitor bank need to be charged to 16.2dc volts (6 times 2.7 volts each capacitor)
    So do you have any idea how to got 16.2 volts from the 12 volts battery in order to keep the capacitors charged in order to hold the peak load when would be needed.
    any idea, advise or circuit, would be highly appreciated.

  6. Hi Miariver, Please Google for a "12V 555 boost converter circuit" you can set and use the output from this circuit suitably for charging the supercaps at 16.5V or at any other desired rate....

  7. Hey tks Swag, very good idea, I will give the try and let you know. please keep the ball rolling. bst regards, MIARIVER

  8. Dear Sawagatam

    Nice circuit for my requirement . Please give me clarification for below 3 questions
    1. resistors all 33 ohms ??
    2. Pin 5 connect to -15v ??
    3. Is this produce sine wave and can be 50HZ

    Please modify or give me suggesions



  9. Dear Chandana,

    Did you read the whole article?

    all fet gate resistors can be 33 ohms or lower

    pin5 is the shut down pin that can be integrated with the last voltage control circuit.

    It's a square wave circuit.

  10. Rt/Ct determines the frequency level...

  11. Hello sir this is John thanks for helping people, pls kindly suggest for me the value of ct pin 3 and rt pin 4 of ic irs2453 at least average value that can work , the capacitor and the resistor, thanks

  12. Hello sir pls help me with the value Rt/Ct pls we are using 220v in our country

  13. Hello Chief Engineer Swag, pls sir suggest for me the Rt/Ct value pls i can not know the value myself please i need 220v 50hz please help me sir.

  14. Hello John,

    you can calculate it using the formula given inthe following article:

    or do it practically through some trial and error using a frequency meter.

  15. Do u have 3 phase to single phase converter with Vfd circuit kit then please let me know & also kits prise list.

  16. sorry presently I do not have a ready made kit for this...


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