Losses in an eccentric rotor induction machine fed from frequency converter

The rotor eccentricity in induction machines has been studied from different points of view as to assess its possible detection. However, most of the inductions machines in industry are allowed to operate under different levels of eccentricity. In this paper we investigate the effect of rotor eccentricity (both static and dynamic) on the power losses of the machine when fed from PWM voltage sources. Already at 30% static eccentricity the rotor resistive loss increased by more than 7%. This increase is crucial for the cooling of the machine. It is also shown that for the same level of eccentricity the static one causes slightly more losses than the dynamic one. Analysis of the torque, phase voltages and currents under static and dynamic eccentricity is also presented.