|
||||||||||
|
||||||||||
16 Jul 2001, 20:39 (Ref:117930) | #1 | ||
Rookie
Join Date: Dec 2000
Posts: 17
|
Electric Motor Torque
This question may not be exactly relevant to motorsport engineering in general, however I think this is the best forum for this question:
Does anyone know how to work out how much torque an electic motor has? From the way I see it, it would be the magnetic force created by the magnet/field windings multiplied by the distance from the centre of the axle to the edge of the armature/coil. If this is true, how could I find how to calculate the magnetic force applied? Thanks Duckers |
||
|
18 Jul 2001, 08:36 (Ref:118698) | #2 | ||
Veteran
Join Date: Apr 2001
Posts: 2,083
|
I'm not sure of any forums.An electrical engineer could definitely help you. OR dick smith catalogs have a torque/speed/load/etc graph in the back with a few formulas !maybe that helps??
|
||
|
19 Jul 2001, 05:50 (Ref:119079) | #3 | |
Rookie
Join Date: Jun 2001
Posts: 15
|
Personally, I'd go with the catalog. Or at worst, dyno-test your motor. If you like doing it the hard way, I can try to explain.
It is possible to mathematically calculate the torque of an electric motor. For simplicity's sake, let's take the 3-arm DC motor (the kind you find on your everyday R/C cars, cd players, etc) For a current-carrying conductor in an electric field, let: F=BILsinA (scalar eq) where F=Force acting on conductor(N), I=current on conductor(A), L = length of conductor immersed in electric field(m), and A is the included angle between the direction of I and the direction of B. We can now take a motor's coil and divide the coil into very short current-carrying wires. Each elemental length of the coil's wire carries the same amount of current but with different directions. In turn, these elemental lengths of the coil will make contributions to the overall force generated by the coil. Now we know that we can split the coil into very small pieces of wire that experience small magnetic forces on their own. Like you mentioned, calculating torque is now only a matter of multiplying the distance of these elemental wires by the distance from the axis. However, you have to remember that every single piece of these very short wires vary in distance from the axis. You also have to remember that as the rotor turns, the electric field strength varies. (depending on design, magnet quality etc) So there, if you can mathematically describe the magnetic force, coil shape and timing, you can take these equations and stuff them into eg MAPLE. However, the number you get (assuming you get the mathematical model correct) would be the GROSS torque rating, and IMHO, not as useful as simply dyno-testing your motor. |
|
|
5 Jun 2009, 15:27 (Ref:2476021) | #4 | |
Rookie
Join Date: Jun 2009
Posts: 1
|
http://www.elec-toolbox.com/Formulas/Motor/mtrform.htm has the formula. The rated horsepower multiplied by 5252 divided by the rpm number achieved when they got the horsepower rating.
|
|
|
5 Jun 2009, 18:48 (Ref:2476124) | #5 | ||
Veteran
Join Date: Aug 2004
Posts: 14,699
|
Blimey an 8 year wait for the answer, I hope it was worth it! Is that a record on here? :-)
|
||
__________________
You can't polish a turd but you sure can sprinkle it with glitter! |
5 Jun 2009, 19:04 (Ref:2476132) | #6 | ||
Veteran
Join Date: Nov 2006
Posts: 9,441
|
budbarker57 welcome to the forum, and you got a comment from Al on your first post ! You must have had a good scan through the archives to have found this prehistoric thread
|
||
__________________
Balls of steel (knob of butter) They're Asking For Larkins. ( Proper beer) not you're Eurofizz crap. Hace más calor en España. Me han conocido a hablar un montón cojones! Send any cheques and cash to PO box 1 Lagos Nigeria Africa ! |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Torque or HP | AlexF | Track Day Forum | 7 | 31 Dec 2003 18:37 |
Torque Bac Stages | Chris Gray | Rallying & Rallycross | 4 | 4 May 2003 20:55 |
Torque vs horsepower | F1 Racer | Racing Technology | 5 | 5 Jun 2001 22:51 |
electric motors for electric superchargers | con-rod | Racing Technology | 1 | 26 Apr 2001 18:00 |