# possible max speed attainable with 1470 rpm ac motor

3654 Views 10 Replies 4 Participants Last post by  venkatesan
The motor i'm planning to use in my conversion of 1500 kg (including battery) is an 11 kw ac three phase 1470 rpm motor. I'm planning to retain the transmission. What could be the approximate max speed of the vehicle in the top (5th) gear. The vehicle is a sedan car.
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Not enough information to speculate.
Need rear axle ratio, final drive ratio, wheel diameter, etc, as a minimum.
But ...as a guess, no more than 20-30 km/hr.
it is front drive vehicle, the tyre size is 175 65 x 14, i am not sure about the final reduction ratio
11kw motor on a 1500kg vehicle is not a lot. Id guess you'll cook it doing 100km/h for more than 30 minutes.

Also the speed is the speed with slip at a certain load with a certain net frequency. (50/60Hz). I guess you'll be using an inverter. That way you can get 22kW output at approx double the input voltage and double the frequency without immediatly overheating it. Eitherway, 22kw is not a lot even with 1500kg.. In fact, you wont notice much acceleration above 70km/h then I am afraid.
karter and steven thanks for your kind reply. My doubt is, does a 11 kw but 1470 rpm motor can propel a 1500 kg vehicle beyond 60 70 kmph.
Do you have specifications of the motor?
yes, it is 11 kw ac 3 phase 4 pole / 1470 rpm / 50 hz / s1 Duty / IP 55
voltage and amp rating is 400 / 690 and 22 / 12.7 @ delta / star identifation plate has been attached

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yes, it is 11 kw ac 3 phase 4 pole / 1470 rpm / 50 hz / s1 Duty / IP 55
voltage and amp rating is 400 / 690 and 22 / 12.7 @ delta / star identifation plate has been attached
Hello ven,

Although it may be possible to use this motor it would be very difficult. It was mentioned to increase in voltage to increase the power and RPM. This is possible but again very difficult as that would involve 800V. That requires on the order of 200 battery cells and is a hazardous voltage. Also the motor controller will be very expensive, large and complex.

I recommend you reconsider and look at a DC system or a package of AC motor and controller intended for EV propulsion.

Regards,

major
hello Major, Shall we consider 50 kmph max as a safe speed. In the case if it is not which could be the safe limit
hello Major, Shall we consider 50 kmph max as a safe speed. In the case if it is not which could be the safe limit
It is not the vehicle speed I refer to as the hazard. It is the voltage level. Most EV conversions done by beginners are below 200V. You need to take caution at that level. Using higher voltage like 400VAC which would require 600VDC battery becomes lethal. Please reconsider unless you are an experienced engineer.
Hello Major, I understood. I will look for other options. Thank you.
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