# Torque curves



## kosstheory (May 26, 2008)

So, I have a friend who wants to try to build the electric motor for my 67' mustang EV conversion. He gave me the equation for to convert current to torque for his motor, but the current draw to torque curvedoesn't seem all that impressive. However, I'm having a considerable amount of difficulty finding comparable charts for some of the standard AC and DC motors that people use on this site.

Does anyone know where I would find this technical info...I'm specifically interested in current draw as it directly relates to torque.

Thanks


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## joseph3354 (Apr 2, 2008)

you can find all of netgains info here: http://www.go-ev.com/


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## kosstheory (May 26, 2008)

Yeah, after examining the data on the Warp9 and the transwarp11

I'd say that there are no performance gains to using his motor, unless we built it to use several rings rather than one, then who knows.

According to the data he gave me his motor would produce very similar results to the Warp11...150amps in 20 ft-lbs of torque out...


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## major (Apr 4, 2008)

kosstheory said:


> I'd say that there are no performance gains to using his motor, unless we built it to use several rings rather than one, then who knows.
> ...


Hi kosstheory,

What are rings?

major


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## kosstheory (May 26, 2008)

Does anyone know what equation would be used to derive Torque from Current Draw in the elctric motors used on this site?

I just want to check the formula that my friend gave me against the formulae for more traditional motors.

Thanks


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## kosstheory (May 26, 2008)

major said:


> Hi kosstheory,
> 
> What are rings?
> 
> major


Unfortunately, he hasn't patented his design yet...Not that I think anyone on here would use his designs, but I don't want to say more than it's my right to say.

At this point I just want to get the conversion done as quickly and effeciently as possible. He wants me to use his motor, but that will require some research and development first. I don't want to do R&D on a motor that will only yield modest performance gains in its standard configuration. Adding 'rings' would be like building consecutive synchronised motors, and I have a feeling that would be too time consuming for this project. Plus the guy's a little flakey, and I don't want to waste my time...


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## SuperChuck_A11 (May 29, 2008)

*Your solution as I see it*"
You need to compare current manufacturers Efficiency Ratings in % with your friends.
150 Amps in and 20 ft-lb out .


kosstheory said:


> but the current draw to torque curve doesn't seem all that impressive.


You will have to develop an Efficiency Rating for his Motor.
*Process is:*
Input:
1. Volts x Amps = Watt- e…Watts-electrical ............................................................................................................*?? Watts= ??* *Volts x 150 Amps *
Output:
1. Torque is Mathematically CALCULATED INTO HorsePower. If you have a Torque rating you need to know the RPM it Peaks. ...*HP = (Torque x RPM) / 5252. *
2. HorsePower is CONVERTED into Watt-mechanical (simply metric equivalents ft'lb into N'm) ...............................................*Watts-m = HP x 746 *
Efficeincy Rating:
1. Watt-m- OUTPUT is divided by Watt-e INPUT to get Efficiency in %. .......(in the real world less than 100%).......................*xx % = Watts-m / Watts-e *

However you didn't mention your Voltage... Or the peak Torque RPM. 



kosstheory said:


> I'm specifically interested in current draw as it directly relates to torque.


Even if you get the math info your asking for you have to compare it to Other Manufacturers to see if it is any good.


kosstheory said:


> However, I'm having a considerable amount of difficulty finding comparable charts for some of the standard AC and DC motors that people use on this site.


They have a Rated Efficiency.
You could just go around looking at different specs, checking efficiency spec to see if he has a good design.
Then you simply pick the highest efficiency rating you can find, all other things being equal.

And since Current draw is directly related to Torque, you will have to decide 
1. What Current Draw you want at WOT and for how long WOT is gonna be (like full quarter a lot) or just leaving stop light..... check out the "White Zombie" Google
2. Match motor Peak Efficiency (RPM not %) with your rear gear for expected cruising. 
Really the whole rings statement is the design difference between a 69 Big Block 454 starter and a Small block starter, just a longer armature and matching magnetic ring. 
Sounds interesting if he can simply add the pieces onto the existing shaft,, stacking them like you can Rotary Motors or the twin Warps, with out the extra bearings and brushes associated with 2 motors.


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## Dennis (Feb 25, 2008)

> *Metric Equivalent HP is not the same as Electrical Watts*


A watt is a watt and therefore it is irrelevant if it's electrical or mechanical there is no difference between them....



> Does anyone know what equation would be used to derive Torque from Current Draw in the elctric motors used on this site?


This does not tell me what type of motor you want the equation for... Is it AC or DC? If its DC is it series-wound, shunt wound, permanent magnet, or is it compound wound? If AC is it 3-phase NEMA design A,B,C,D or is it synchronous?

Why not just buy a series-wound motor like a warp 11? The torque formula for a series wound motor is: Tmechanical =kI^(1+α ) - Tfriction. Honestly though its better off just to look at the data provided by the manufactureres. If you wish to extrapolate past their data say you want to know how much torque the motor produces at 1000 amps then you will need some special math software that can find the data of the curve for you to plug into the formula for k and α. "I" is no a brainer since you want 1000 amps so I = 1000 amps. Friction will have to be estimated.

Now under current limit conditions the torque curve will be flat instead of what it would be under no current limit. I have explained this many times why this happen and will not do it again. To find out more simply click on my screen name and search through my previous posts.


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## SuperChuck_A11 (May 29, 2008)

Dennis said:


> A watt is a watt and therefore it is irrelevant if it's electrical or mechanical there is no difference between them....





Dennis said:


> quote]
> 
> Kinda Agreed,
> but it is very confusing when your throwing specs around and doing conversions it helps to keep them straight by differentiating between them.
> ...


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## Batterypoweredtoad (Feb 5, 2008)

Dennis said:


> ....
> Now under current limit conditions the torque curve will be flat instead of what it would be under no current limit. I have explained this many times why this happen and will not do it again. To find out more simply click on my screen name and search through my previous posts.


Hey Dennis, could you explain to me what the torque curve would look like on a current limited controller please?


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## 3dplane (Feb 27, 2008)

Yeah Dennis, quit hogging the torque curves!(just joking!!!)
BTW (Dennis) thanks for the input on those previous posts I learned a lot after a few weeks of digesting.Barna


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