Non-sinusoidal rotor bar current phenomenon

What is it about?

Stator currents of a 3-phase IM fed with a 3-phase balanced sinusoidal voltage are sinusoidal according to the equivalent circuits commonly used for the machine models. Therefore, the rotor bar current is also considered as sinusoidal because of the sinusoidal induced voltage in the rotor bars. However, the rotor current is often observed to be quite non-sinusoidal in some cases, such as at very high speeds, or at higher voltages than the rated voltage, or at lower frequencies than the rated operation frequency of the machine.

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