How does the torque behave at low and high speed in 3 phase induction motor?

Answer 1

I believe you are going to experience torque "ripples" known as "cogging". This is usually of little consequence, unless you are trying to provide force-feel feedback with the motor back to a human pilot or controller of a process or piece of equipment.

The pole attraction that drives the motor is non-linear. This may be countered somewhat by commutating the input signal to the poles - varying its shape to match the non-linearity of the poles. This helps, but doesn't completely eliminate the phenomena.

So one is left to add damping to try to damp the remaining ripple, if it is important.

The ripple may be more noticeable and be more pronounced at higher speeds (more inductive effect of poles passing through magnetic fields), and one has to watch resonance built mechanically into the system driven by the motor.

Answer 2

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