Asynchronous Machine runs in reverse when no voltage is applied.

Hello.

I use an Asynchronous Machine (SI) in Simulink to control a positioning system. But when I start the simulation the motor runs in reverse even if the voltage is not applied to the stator terminals. It does run in reverse when I connect Tm (including 0). I use present model 15 but whatever model I use it behaves like that. If the input is disconnected the motor is working properly.

[Joel Van Sickel]

Can you share the model, or at least a screenshot? i have used a few of our Asynchronous Motor models and they work as expected when 0 volts is applied.

Regards,

Joel

[Plamen Ivanov]

Thanks for your answer.

It is interesting because it does the same thing even when I use tree AC sources. Of Tm is greater the 0 is is always like this.

Answer 1

[Joel Van Sickel]

The issue is that you are applying a non zero torque to the machine. This is a constant torque which will put a rotational force on your machine regardless of what the AC system voltage is doing. This is expected and appropriate behavior when Tm is non zero. If the input voltage is disconnected, any torque, no matter how small, will spin the motor. You will need to create a more detailed model of when torque is and is not applied externally. The model makes sense at first because the applied voltage is creating a torque greater than the external torque, so it spins the motor as you'd expect, but once the electrical torque is no longer applied, there is only the external mechanical torque of Tm which is spinning the motor.

Regards,

Joel

[Plamen Ivanov]

Thank you very much