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Problem with making inverter

Discussion in 'Power Electronics' started by New Student, Sep 19, 2021.

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  1. New Student

    New Student

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    Sep 19, 2021
    [​IMG]

    Hello everyone !!!

    I got a problem with this schematic diagram..
    When i do it practically i got a 1 mosfet get hot and another one cold..

    In my opinion i think the hot one is in working but the other one is not working .. when i try change between these two mosfet it also same that Q1 mosfet only hot..

    If someone have any advise to me. Im really appreciate it.. thanks you.

    From newbie student in electronic (•_•)
     
  2. Bluejets

    Bluejets

    5,037
    1,052
    Oct 5, 2014
    Show how you have it wired up.
     
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  3. Audioguru

    Audioguru

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    Sep 24, 2016
    A fake CD4047 or fake IRF540 from ebay?
     
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  4. bertus

    bertus Moderator

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    Nov 8, 2019
    Hello,

    Did you connect the mosfets correct?
    irf540 pins.png
    n-mos connections.png

    Bertus
     
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  5. New Student

    New Student

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    Sep 19, 2021
    Hello thanks for help i try it on breadboard using wire awg20 .. i will upload the picture later
     
  6. New Student

    New Student

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    0
    Sep 19, 2021
    Thanks for help.. im also not sure i buy it from electronic shop.. cd4047 from "st" brand and mosfet i buy from 2 different shop but it also get same result
     
  7. New Student

    New Student

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    Sep 19, 2021
    Thanks sir for help... I connect gate to no 10 ic leg and another mosfet gate to no 11 ic leg... For drain i wire to 0v trafo and another one also same to another 0v trafo... For source i jumper that two leg connect to -negative.. i think it same like a picture..
     
  8. New Student

    New Student

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    Sep 19, 2021
    Okey im also try test using led... leg 10 and 11 ic using led... but my result is leg 10 is on and another 11 leg also on... It not make flip flop.. can someone explain why it cannot be flip flop... Im already get research from an internet but i dont have that answer.. if someone know why this happen please help and guide me to finish my fyp project.. thanks all
     
  9. bertus

    bertus Moderator

    2,062
    777
    Nov 8, 2019
    Hello,

    At about 50 Hz, the leds will look like both are on as they are switched to fast to see them blinking.

    Did you wire the transformer correctly?
    Is it a transformer with two separate coils?
    The connect it as : (Drain Q1 to 12V first coil) , (0V first coil to12V second coil to + 12 V power) and (Drain Q2 to 0V second coil).
    (assuming there is a 12V transformer).

    Bertus
     
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  10. Audioguru

    Audioguru

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    Sep 24, 2016
    Maybe you connected the Mosfets and transformer wires backwards.
    Nothing on the transformer connects to 0V except the metal frame. The drains of the Mosfets connect to the transformer outer 12V wires and the transformer center tap connects to +12V.
    The sources of the Mosfets connect together and connect to 0V, there is no -negative.

    With R5 at 390k and C2 at 0.01uF (sometimes marked 103) then the outputs pin10 and pin11 of the CD4047 turn on and off at 60Hz that looks like LEDs are continuously turned on or a multimeter shows a continuous voltage. Use 470k for R5 for 50Hz.
    To see LEDs turn on and off alternating then replace C2 with 0.22uF (marked 224) but the frequency will be 2.7Hz which is too low to drive a transformer.

    When pin10 of the CD4047 goes to +12V then its Mosfet turns on and its drain goes to 0V. When pin 10 goes to 0V then its Mosfet turns off and its drain goes to +24V. Pin 11 and its Mosfet do the opposite so at any moment only one Mosfet is turned on.

    This is a high power inverter that cannot use a low current breadboard and small 20awg wires. Maybe your transformer is too small to make 50Hz power and is not 24V center-tapped (12V-0-12V).
     
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  11. New Student

    New Student

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    Sep 19, 2021
    Yes sir i think i make correctly.. i will try another one... Now i try remove all wire and try another but see only one led(1) is on and another one led(2) off... Also when it on off and on off the switch i see sometime led(1) off and another led(2) on.. but i need to on off and on off from battery switch
     
  12. New Student

    New Student

    13
    0
    Sep 19, 2021
    Thanks sir..
    Thanks sir for that information clearly...
    Can u suggest what type of wire i need to use and type of transformer that suitable.. or any link there that u can share... Oh i my transformer that i use now is (12-0-12) is it not suitable? U mean i need a transformer (24-12-0-12-24) like this ya? If it has a link to give im very appreciated to get that transformer... Thanks sir
     
  13. Audioguru

    Audioguru

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    Sep 24, 2016
    Your 12V-0-12V transformer is fine if it and the wires can carry the needed current.,
     
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  14. New Student

    New Student

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    Sep 19, 2021
    I use single core 20 awg that common use for high amp motor.. is that make any problem with my case or not sir?.. that cable quite thick ..

    Thanks sir for help
     
  15. New Student

    New Student

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    Sep 19, 2021
    Sir i want try to change my resistor as ur guide..
    I want to make sure is that 390k R5 OR R3 that need to change to 470k res.. in that R5 1k just for led to show that battery is on and as a indicator... U mean i need change R3 TO 470k right sir?
     
  16. bertus

    bertus Moderator

    2,062
    777
    Nov 8, 2019
    Hello,

    You can calculate the timing of the chip:
    4047_timing.png
    Use the free running line of the table

    Bertus
     

    Attached Files:

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  17. Audioguru

    Audioguru

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    Sep 24, 2016
    A wire gauge table shows that little 20AWG wire has a maximum allowed current of only 6A.
    The inverter Mosfets and transformer produce some heat so the efficiency is about 80% then the max of 6A has only about 5A of current from the 12V battery used for output power resulting in an output of only 5A x 12V= 60W maximum power allowed from the inverter.

    Obviously R5 and R6 set the output frequency. Simple arithmetic shows 58.1Hz to 58.3Hz when R5 is 390k ohms and the capacitor is 0.01uF. For 230VAC you probably want 50Hz and using 470k for R5 results in 48.4Hz.

    I think that R1 and D2 should be replaced with pieces of wire.

    Many electronic products will not work from the squarewave output of this simple inverter because they need the higher peak voltage from the normal sinewave used for electricity.
     
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  18. New Student

    New Student

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    Sep 19, 2021
    Thanks sir ... I will study a little about this ic.. thanks for sharing
     
  19. New Student

    New Student

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    0
    Sep 19, 2021
    Yes thanks for that information sir... Finally i make as u share and it work.. very2 thanks sir .

    Yes this for small and simple inverter. In case i want to increase that watt .. i need to use more mosfet. Is it true or not sir? Or i need parallel the transformer to give more amps?

    My case for simple inverter now is done.. thanks to all of you that help and give me guide to this project final in my colleague... Im appreciate it.. i will try my best to go make sine wave after this i think... Thanks all
     
  20. Audioguru

    Audioguru

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    733
    Sep 24, 2016
    The datasheet for the IRF540 Mosfet shows that its maximum allowed current is much more than 6A. Then it will get hot so a heatsink must be used and its size can be calculated.
    You never told us the maximum power rating of your transformer. For more power usually a larger transformer is used instead of paralleling more little transformers.
     
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