AWG gauge choice and assistance!!

Discussion in 'General Electronics Chat' started by gusmas, Jul 22, 2013.

  1. gusmas

    Thread Starter Active Member

    Sep 27, 2008
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    0
    Hi

    I need to wind a inductor which will experience the following:

    It will be used in a buck-boost converter.

    PWM Freq: 20kHz
    Max Load Current: 20A

    Now using the following link: http://www.powerstream.com/Wire_Size.ht,to get the wire thickness. However the wire that can handle 20kHz (AWG 19) is only able to handle 1.8A?

    Am I missing something here? I hope I am.....

    Thanks
     
  2. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    The link provided, indicated a URL fault, but gave a route to the "ampacity" table.

    You need something to handle 20 amps, this will be at least # 12 awg.

    Re; A standard household AC Outlet, provides 15 amps, and is wired with a minimum 14 awg. Please refer to National Electrical Codes...

    Frequency will speak for itself, as a function of the core material you wind your project on... and the number of turns to do the deed. Those are your major considerations, and more math than is called for here...:D
     
    Last edited: Jul 22, 2013
  3. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    239
    0
    whoops:

    http://www.powerstream.com/Wire_Size.htm

    if I may ask how did you get I must use at least a #12 awg? Was that a estimation from the "Re; A standard household AC Outlet, provides 15 amps, and is wired with a minimum 14 awg." statement?
     
  4. Evil Lurker

    Member

    Aug 25, 2011
    117
    23
    The inductor would have to be huge to support that frequency (along with the wire gauge) and so would the caps to handle the ripple current. You need to increase your frequency to 100khz+ IMO.
     
  5. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    239
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    Cap is sorted. Just need my inductors :)
     
  6. Evil Lurker

    Member

    Aug 25, 2011
    117
    23
    How much inductance do you need?
     
  7. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    239
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    any value between 20uH and 500uH
     
  8. BobTPH

    Active Member

    Jun 5, 2013
    782
    114
    Haven't designed many switching power supplies, have you?

    Bob
     
  9. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    239
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    no, designed from what info i could find on internet.
     
  10. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    I am a 40+ year household DIY, and have done beau-coup wiring, and even though not "licensed" I work under the purview of a licenced electrician, and subject to the same NEC and local codes, just as he is...

    regarding electricity - amps are amps, whatever house they live in... whatever any given component tells it what to perform... it takes #12 awg or [sch]metric equivalent , to handle 20 amps current. Some will tell you that #14 is ok, here's the difference... I tend to lean toward overkill with things Electric / electronic.
     
    Last edited: Jul 22, 2013
  11. BobTPH

    Active Member

    Jun 5, 2013
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    I suggest you do some simulation then, or analysis to determine a little more carefully what inductor you need. A 20uH and 500uH will perform very differently.

    What are the input and output voltage and current requirements?

    Bob
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,126
    3,048
    Not if that "house" is a coil that cannot dissipate much heat. Linear insulated wire ratings would be different than coiled magnet wire inside a shielded enclosure.
     
    PackratKing likes this.
  13. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    239
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    I have simulated my design for both inductor values and it worked as intended (i think its luck :p). Maybe my mistake was saying between 20u and 500u (inexperience). Lets say either of those values, i need a inductor for.
     
  14. BobTPH

    Active Member

    Jun 5, 2013
    782
    114
    With a load of 20A and you got the same results?

    Bob
     
  15. gusmas

    Thread Starter Active Member

    Sep 27, 2008
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    yes. See attached documents. first one is at 20uH, second one is 500uH
     
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    • 500.jpg
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  16. tindel

    Active Member

    Sep 16, 2012
    568
    193

    Can you really take ~25V of overshoot on your 50V rail? That's 50% overshoot, and I see it on both simulations.
     
  17. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    239
    0
    That is without soft startup. I am going to use a micro to control the pwm duty cycle, so will start at close as possible to 0% and slowly ramp it up.
     
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