Scrounging AC Electric Car Motors

by Peter
(Queensland, Oz)

What else are 3-phase AC induction motors used for? In other words, can old ones be scrounged for your electric car conversion?

Hi, Peter!

Sure, old electric motors can be scrounged. You can find 3-phase AC induction motors (that's what you're looking for) in modern forklifts, for example. There are probably other sources, and I encourage other people to comment.

Here's my observation, for what it's worth: a suitable motor is doing similar duty. In other words, for your EV, look for a motor that's moving a vehicle. A motor that's moving an airplane wing up and down CAN be pressed into service, but it's probably not the best man for the job.


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Electric Car Motor: Duty Rating

by Patrick

Will a 3 phase electric motor from an older air compressor work for an electric car conversion?

Hi, Patrick -
There's a reason why people choose "intermittent duty" over "continuous duty" rated electric motors for their electric car conversions.

The industrial motors tend to be heavier and bigger for the power you get.

Read this article on why people choose OEM electric car motors for their conversions instead of other types of electric motors that would seem to be suitable because of their weight or application.


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Single Phase AC Motor for an EV?

by Ed

This Cat Likes the Single Phase AC Motor.

This Cat Likes the Single Phase AC Motor.

I have a commercial washing machine with a large single phase AC motor and a sophisticated controller with capacitors & direction reverser. I hate to throw it out. Can I use it to build an electric car?

Hi, Ed!

Let's ask Dan Bentler, our favorite motor man; )

Dan says:

"With vehicles you want variable speed. You can change final speed by either changing gear ratio (transmission in gas engine car) OR by varying motor speed. In the past that was done with DC motors. Currently the easiest way with AC motors to get variable speed is 3 phase inverter ie VFD which give a variable frequency output. AC motors run at speeds proportional to frequency ie 2 pole at 3600,, 4 at 1800 etc. Voltage is also controlled (about 7 volt per Hz for a 450 V motor BUT only to keep the motor from burning up at lower freqs due to lower inductance.

Single phase LARGER motors their phase shift is obtained by
a difference in the current in two fields i.e. difference in each field current laggging the voltage
inductance with different size windings (different inductance)
capacitors either start or run or both. What this means in effect is that a single phase motor can run at only one frequency or you result in throwing off the phase shift values thus currents and screw everything up - it won't run or it may burn up. Thus single phase motors are tuned / designed to run at a single frequency.
So could it work YES
BUT he would have to have a mechanical means of varying speed.
There are belt type speed changers made but I am not sure if he could get the speed change range he needs.

Recommendation - save the motor for a different project - they are good hefty motors and can do lots of good things properly applied."


P.S. You can read more about AC and DC electric car motors here.

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