Measurement proven analytical and numerical models for calculation of the teeth flux pulsations and harmonic torques of skewed squirrel cage induction machines

An analytical approach to calculate the tooth flux pulsations of stator and rotor teeth in squirrel cage induction machines at sinusoidal voltage supply [1] is compared with FEM (Finite Element Method) results. The analytical approach allows the fast calculation of the losses due to the tooth flux pulsations in the stator and rotor at any given slip, load and saturation level. In addition, the analytical calculation of the torque curve during start up is discussed considering the harmonic torques and the effect of inter-bar currents in skewed rotor cages. Calculations and measurements are compared for 4-pole TEFC (Totally Enclosed Fan Cooled) standard induction motors with nominal power levels of P_N = 0.75kW, 2.2kW and 9.2 kW.