Computation of no-load iron losses including spatial harmonics and tooth pulsation components for cage motor

Abstract

The contribution of spatial harmonics and tooth pulsation in iron losses of three phase squirrel cage induction motor has been calculated using lumped circuit approach. An equivalent circuit of the three phase induction motor considering stator magnetomotive harmonics has been used for the calculation of the same. An empirical formula has been developed and validated for determination of tooth pulsation losses. The usage of lumped parameters circuit considering magnetomotive force harmonics for predicting the iron losses components has not appeared in the literature. Here iron losses due to fundamental, spatial harmonics components and tooth pulsation for various motors with different designs and polarities have been deter-mined and compared with experimental results. It is found that the iron losses due to the stator magnetomotive harmonics is in same range as that due to fundamental component, the tooth pulsation losses are in the range of 25 to 35% for 2 pole, and 20 to 30% of total iron losses for 4 pole induction motors. The percentage errors between computed and average experimental results for total iron losses are within acceptable limits (±5%) without taking too much of computation time compared to the numerical methods.