Determination of iron loss considering spatial harmonics and tooth pulsation effects for cage motor

The contribution of spatial harmonics and tooth pulsation in iron loss 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 loss. The usage of lumped parameter circuit considering magnetomotive force harmonics for predicting the iron loss components has not appeared in the literature. Here iron loss due to fundamental, spatial harmonics components and tooth pulsation for various motors with different designs and polarities have been determined 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 loss is in the range of 25% to 35% for 2 pole, and 20% to 30% of total iron loss for 4 pole induction motors. The percentage error between computed and average experimental results for total iron loss are within acceptable limits (±5%) without taking too much of computation time compared to the numerical methods.