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Old Apr 13, 2011, 12:49 PM
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Joined Mar 2011
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Winding turns calculation.?

Hi,

i have permanent magnet DC motor and it s attributes :
Voltage=12 Volt
Current=2,5 A (No Load)
RPM= 3000 rpm (No Load)

lamination size :
diameter :81 mm
lenght :21 mm
Pole : 4 poles (N-S , N-S)
Each magnet has: 1000 gauss
Brush :4 brushes
Hook count:20

and windings of this motor is: 0.80mm(diameter) x 14 (turns)

Firstly anyone can express me how can i design dc motor with formulas? i mean how will i calculate Resistance of windings?( and how will i canculate others (R, E, I)?(current division factor?resistance and magnetic flux... i cant realize how will i use them....?there are 4 poles but must i use just N pole counts?

Another Subject , i want to design this motor in 24 V (Current and RPM, magnets, size will be the same, i can change only winding turns and wire diameter). How can i do it? anyone can express me with formulas?
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Old Apr 13, 2011, 02:42 PM
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Carmichael, CA
Joined Feb 2007
3,532 Posts
I use this thread as a primary reference for motor equations on RCG:
http://www.rcgroups.com/forums/showthread.php?t=587549

Kv is related to the termination and # of turns for a given motor... Kv*turns=constant. Be aware there are winding schemes that may physically have 12 loops of copper, but as far as physics and math are concerned they are really 6T (4T, 3T... endless possibilities). So you also must take note if the wind is terminated with parallel coils or not.

Once you establish Kv*T for your motor, you can design the number of turns/termination that will give your target Kv for your application. The exact Kv depends on how your load behaves. The dynamics of your load is something that motor equations won't help with. So you also need to put a number on operating torque.

With double the input power at the same RPM, hopefully you'll operate at least double the torque, otherwise efficiency will be lower than the original. That said, if you're running the same torque and RPM, the current could be a bit less than half the original (more efficiency as amps drop). Hope this $.02 helps... there are much more knowledgeable motor calc guys out there who might chime in with the good stuff.

Cheers,
Kev

edit: regarding wire thickness... calculate the total cross sectional area of the original windings, and try to meet or exceed that as best you can. More copper area is ALWAYS better.

Wait a minute... just noticed "brushes"... this info pertains to brushless, LOL! Sorry.
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Last edited by Truglodite; Apr 13, 2011 at 02:50 PM.
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Old Apr 14, 2011, 01:13 PM
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Joined Mar 2011
97 Posts
i cant winding 2 x Nold(14 turns) for my motor. Because physical size of my armature is not available(for 28 turn, 0,80 milimeter diameter wire.).
12V, 14 turns, 0.80 mm diameter.
24V, X , X ?
Armatures are the same in both motors. if i design 24V 0x55 mm and 28 turns so could be done well?
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