help-needed-push-pull ckt...

Discussion in 'General Electronics Chat' started by RRITESH KAKKAR, Nov 22, 2012.

  1. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    Hi,

    I have 12 0 12V transformer of 30A max transformer of UPS which has 4-5 tapping at output for AVR (external) and the circuit is working fine i have tested 200Watt BULB and 300Watt Drill machine running.
    the amp meter was showing more than ~15A at heavy load from 12V 7AH battery of UPS. so i guess the output power tested till now is 24Vx15A =360VA.
    The no-load current taken by Transformer is 900mA. as there is no voltage regulation circuit so voltage fall down at load.
    Someone suggest me to use 3524 PWM modulator. please help me with it as data sheet suggest the working freq range from 10hz to 400khz but in India 50hz is working freq., so, what to do??
     
  2. Audioguru

    New Member

    Dec 20, 2007
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    The SG3524 and TL494 ICs are used in pure sinewave inverters (not in simple modified sinewave inverters). Their oscillator operates at a high frequency, maybe 100kHz and is Pulse-Width-Modulated with 50Hz or 60Hz.

    Because the oscillator frequency is high then a small ferrite stepup transformer can be used.

    Look for Pure Sinewave Inverter Circuit in Google.
     
  3. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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  4. Audioguru

    New Member

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    The circuit is missing an LC filter at the output to smooth the high frequency PWM pulses.
     
  5. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    Can you provide me a standard ckt from where i can start.
     
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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  7. Audioguru

    New Member

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    I have never needed and have never used an inverter.
    I have been to large picnics where a gasoline engine powered alternator was used instead of an inverter.
    Buy an inverter, take it apart and see all the parts it uses.
     
  8. RRITESH KAKKAR

    Thread Starter Senior Member

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    AG its my FYP
     
  9. RRITESH KAKKAR

    Thread Starter Senior Member

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    Why output is taken from em miter not from collector and why 1W pull up resistance are used can't we use less power resistance??
     
  10. Audioguru

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    The outputs of the transistors are the collectors that drive the transformer.

    The power supply voltage is 28VDC so the 1k resistors dissipate at least 400mW. A 1/2W resistor would be VERY hot.
     
  11. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    on ckt it is 12V DC and what is the need of below chip..
     
  12. Audioguru

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    Please learn about the basics of electronics before you copy somebody's circuit of a pure sinewave inverter. Look at the fairly low output current of an SG2524.

    You said it is your FYP. First Year Project?
     
  13. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    but i am talking of voltage, OK can u provide a stand ckt which i can use having voltage regulation.

    Yes...
     
  14. Audioguru

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    If your output transistors are Mosfets then the IC voltages driving them is fine. But if your output transistors are ordinary bipolar transistors then their bases need a lot of current that the IC cannot provide.

    Are you learning how to simply copy and simply solder parts together?
    In university I learned how to DESIGN my own circuits, not simply copy a circuit.

    Do you want a modified sinewave (almost a squarewave) output or a pure sinewave output from your inverter?
     
  15. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    You are right but i have no idea how to design.
    I will prefer to sin wave.

    Anyway, i have gone to UPS production company in my town the owner was an Engg he inform me that in my circuit to add the short ckt protection at every Mosfet.
     
  16. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    AG i want to make MOSFET protection ckt please help me, i have Google and found there was lot of chip used for it but can u provide me a basic/ simple schematic?
     
  17. Audioguru

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    What does a "Mosfet Protection Circuit" protect against?

    A shorted output or a load that draws too much current?
     
  18. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    both will be super...
    This was the ckt provided by that Engg.
     
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