High-Frequency Loss Calculation in a Smooth Rotor Induction Motor Using FEM

In this paper, a new approach for the calculation of high-frequency losses in induction motors is presented. The input to the motors is assumed to be supplied from a sinusoidal voltage source. The method is based on the two-dimensional (2-D) field solutions of the magnetic circuit, obtained by using a nonlinear ldquoharmonicrdquo solution. Hence, the solution time is very short. From the ldquoharmonicrdquo solution, the air-gap field distribution as well as the fundamental frequency eddy current losses are determined. The high-frequency loss calculation is based on the assumption of a path for eddy currents within a lamination. A constant k is introduced that defines the width of the current flow path. The empirically found k value is verified by a theoretical calculation. The new method is applied to the calculation of losses of two smooth rotor induction motors. The prediction accuracy is found to be very good. The method is also applied to two open rotor slot motors to observe the change in the prediction accuracy. It is found that due to the small slot openings accurate predictions are still possible. The approach presented in this paper requires little time for loss calculation, and is very suitable for minimizing losses at the design stage.