# 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
239
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...

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
0
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
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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
782
114
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 ). 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
239
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yes. See attached documents. first one is at 20uH, second one is 500uH

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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.