B Single phase induction motor Torque under increased frequency and Same Current

[StoyanNikolov]

TL;DR Summary

Single phase induction motor Torque under increased frequency and Same/Constant current.

Hi ,

Consider Single phase induction motor.

What will be torque of induction motor, if we increase supply frequency 10 times, if the motor uses same supply current.

Let's say Torque (Supply frequency 50 Hz, Supply current 10 Amperes ) = N

What is Torque (Supply frequency 500 Hz, Supply current 10 Amps) = ?

Will it be 10*N ?
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Also what will be the Output Power?

Let's say Power (Supply frequency 50 Hz, Supply current 10 Amperes ) = NWhat is Power(Supply frequency 500 Hz, Supply current 10 Amps) = ?
Thank you.

 

[jrmichler]

Same current = same torque.
Ten times frequency = 10 X RPM.
10 X RPM * same torque = 10 X power.

But you will need 10 X the voltage to get that much current at that frequency. The rotor and bearings are normally not designed for that speed, so it could self destruct due to rotor hitting stator at critical speed or bearing failure or rotor exploding or stator windings shorting or cooling fan exploding or ....

 

[StoyanNikolov]

Thank you for Reply. It is idealised situation .
No friction.
No Eddy current losses.

So Torque doesn't increase if we increase supply frequency, when motor uses same current.

 

[alivakilian]

The torque is related to I*ø . With higher frequency, the flux will be reduced and you have to maintain it with the voltage .
Simple simulation can help to try different scenarios. Is there any easy to use simulator for electrical motors?

 

[Sarawestern]

The torque is related to I*ø . With higher frequency, the flux will be reduced and you have to maintain it with the voltage .
Simple simulation can help to try different scenarios. Is there any easy to use simulator for electrical motors?

There are a lots of software you can use to model motors. Some of them using Finite Element Method and some just use the analytical models. Of course the analytical models are faster, but FEM results are more accurate and trustable. According to my own experience, I used EMWorks software. I think it has both simulation models and you can Choose to use FEM or not. search them on net and you will find useful videos as tutorials to start.