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Boost converter current calculation

BlackMelon

Aug 7, 2012
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Hello there!

I'm designing a boost converter by using this book:

http://www.mediafire.com/view/00awc...tronics_-_D._Hart_(McGraw-Hill,_2010)_BBS.pdf

From Example 6-4 of page 216, I want to calculate an inductor current but my load resistance is only 1 ohms (since I want the circuit to be able to supply 12V 12A dc motor from a 1.5V battery). The result that I've got is 123.45A of inductor current. My questions are..

1) Did I make any mistakes?
2) If not, do I need a very very large wire to withstand the current?


Thank you
BlackMelon
 

OLIVE2222

Oct 2, 2011
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for the inductor Inom = (Uout/Uin)* Iout, so rawly 100A
do yo really expect to supply the motor from a 1.5v cell?
 

BlackMelon

Aug 7, 2012
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Yeah, I think may be 2-3 cells in parallel might be lighter than a 12V battery...

So how to deal with the current? It's kind of massive >_<
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Get a large 2V lead acid battery.

It will need to be somewhat larger than a 12V battery used to power the same load due to the inefficiencies of the boost converter and higher I²R losses.
 

OLIVE2222

Oct 2, 2011
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definitively the better way to drive a 12V motor is a 12V battery , you must have very good reason to don't do it so.
 

BobK

Jan 5, 2010
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For the same chemistry, the same weight of battery will provide roughly the same amount of power no matter what the voltage is. So adding a boost converter (which, in this case would be heavy because of the massive inductor you would need), does not help at all. Use a 12V battery.

Bob
 

OLIVE2222

Oct 2, 2011
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That's cool thank you Kris, may I ask you the battery Digi-key part number? ;)
 

BobK

Jan 5, 2010
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Damn, I just looked it up in Digikey and they only sell in QTY 1000.

Bob
 

BlackMelon

Aug 7, 2012
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My idea just collapsed!!! lol, 14.8V or 11.1V LiPO might be the best solution :D

PS: If I want to drive 12V DC Motor with 14.8V, can I just control the maximum duty cycle of a motor driver board to be less than 12/14.8?

Thank you everyone
 

OLIVE2222

Oct 2, 2011
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14.8 for a 12V motor will probably not be a problem, but yes if you have a driver board you can adapt the duty cycle accordingly.
Whta's your battery capacity?
 
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