Stray load loss analysis of cage induction motors considering inter-bar currents using 3-D finite element method

In this paper, we investigate the main factors of the stray load loss of cage induction motors from both results of the measurement and analysis. The losses generated at the rotor cage, stator and rotor cores are calculated by the finite element analysis, respectively. To consider the inter-bar current loss, which is produced by the eddy currents at the rotor core between the bars, the 3-D analysis considering the lamination of the rotor core is applied. On the other hand, the total and stray load losses of the motor are measured due to the IEEE standard 112 method B. The relationships between the measured losses and the practical losses generated at each part of the motor are investigated from these results. It is clarified that the main parts of the stray load loss in case of the analyzed motor is the increase of the harmonic rotor cage and rotor core losses, especially, the harmonic inter-bar current losses caused by the stator slot ripples