# Thoughts on Motors



## yodle12 (Feb 4, 2013)

Hi Everyone,
I've been thinking about a conversion for quite some time, and recently came across a great deal on a few motors. I was wondering if I could plumb your collective wisdom for thoughts about whether any of these might work?

Motor Manufacture: US Motors
Catalog Number: D20E2H
Model: T608A
Phase: 3, Volts: 200, Amps: 57, RPM: 1770
HP: 20, Rating: Continuous
Dimensions: 26 inches long x 16 inches wide x 12 inches tall

Motor Manufacture: Leeson
Model: C256T17FB6C, Serial: 070060
Phase: 3, Volts: 208-230/460, Amps: 52-48/24, RPM: 1755
HP: 20, Rating: Continuous
Dimensions: 24 inches long x 12 inches wide x 12 inches tall

Motor Manufacture: WEG
Model: TERB256T
Volts: 208-230, Amps: 48, RPM: 1765
HP: 20, Rating: Continuous
Dimensions: 25 inches long x 16 inches wide x 13 inches tall

Motor Manufacture: WEG
Model: W21
Phase: 3, Volts: 208-230/460, Amps: 47/23, RPM: 1765
HP: 20, Rating: Continuous, Weight: 273 Pounds
Dimensions: 25 inches long x 16 inches wide x 13 inches tall


I've read in other forums that the AC thing can make charge controlling challenging/costly. I guess I'm wondering how much of a tradeoff there is there? It looks like I could get any of these motors for $300-400. Am I going to wind up paying more down the line for charge controlling?

Otherwise do the specs seem decent? Any thoughts would be much appreciated!


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## Ampster (Oct 6, 2012)

I have an AC Motor and separate motor controller and charger. My controller was programmed for my motor. My charger runs off 240v 40 amp circuit in ny garage and charges my pack independant of the the motor controller. It is a very simple setup.

I think it would be wise to consider the motor and controller as one system. You may be able to find a cheap AC motor but unless you find a good controller you may not get optimum performance. Yes AC systems are more expensive, generally than DC but there were several benefits to me that outweighed the cost.


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## E30_Dave (Apr 19, 2012)

I agree entirely with Ampster.

In addition, I would observe that the speed at which all these motors are rated is quite low, and also that one of the most important figures you need to consider is missing: That being torque - the only quoted figure which can give you an idea of how your converted vehicle will perform.


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## Siwastaja (Aug 1, 2012)

E30_Dave said:


> In addition, I would observe that the speed at which all these motors are rated is quite low


It is naturally the speed at 60 Hz. It means it's a 4-pole motor -- just the "correct" one.

For higher rpm, torque starts going down when increasing frequency if voltage is not increased at the same time. Therefore, the OP should consider using at least 400-500V battery pack or reconfiguring the motor windings for lower voltage, to get decent torque at higher revs out of the motors. Added internal cooling may be needed.



> and also that one of the most important figures you need to consider is missing: That being torque


You can calculate the nominal torque from power and rpm rating. This same torque will be available throughout the whole rpm range, until you hit the point where you cannot increase voltage and/or cooling anymore; this region is called constant-power or field-weakening region.

Additionally, you can get up to 3x nominal torque as peak torque, however this will heat up the motor quickly, much more quickly than overclock&overvoltage&overspeed combo to get the same power would do.


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## yodle12 (Feb 4, 2013)

E30_Dave said:


> I agree entirely with Ampster.
> 
> In addition, I would observe that the speed at which all these motors are rated is quite low,.


Thanks, that's a good thought. I was worried about the low speed too, although it seems like it would be plenty if I had a 1:1 gearing ratio (like direct drive?). I guess that might put me on the lower end of power.

From what I can tell this is a motor that was used to drive a municipal pump. Maybe this isn't the best type of motor for this application.

Thanks for helping out with your ideas.


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## yodle12 (Feb 4, 2013)

Ampster said:


> I have an AC Motor and separate motor controller and charger. My controller was programmed for my motor. My charger runs off 240v 40 amp circuit in ny garage and charges my pack independant of the the motor controller. It is a very simple setup.
> 
> I think it would be wise to consider the motor and controller as one system. You may be able to find a cheap AC motor but unless you find a good controller you may not get optimum performance.


Thanks so much for your ideas. I was curious about controllers. I figured that since the motor was simple 60 Hz AC motor there would be some standard controllers available, and it wouldn't need much tuning. 
What software did you use to program your controller?
Thanks!


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## PStechPaul (May 1, 2012)

If you plan to go with direct drive through a standard differential of about 2.5-3.5:1, you will probably need to use a motor rated at least 40-50 HP to get enough low end torque. With a transmission, 20 HP is just about adequate for a small vehicle.

There are some different motor designs (A, B, C, and D) with different speed/torque curves. Also consider the efficiency and if it is rated for inverter duty. You might find a standard VFD controller which can be set up for torque control rather than speed, as that is better for EVs.


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