Analytical model for predicting AC losses in form-wound machine windings due to stator current interactions

This paper presents an improved analytical model for predicting the ac losses in form-wound windings used in high-performance ac machines attributable to the stator currents. The complete model comprises two sub-models that separately calculate the ac losses contributed by the in-slot and end-winding portions. 3D finite element analysis and experimental tests are conducted to demonstrate the usefulness of the model. The results also confirm the vulnerability of form-wound windings to steep increases in the winding ac resistance as the excitation frequency increases. The model is subsequently used to investigate the impact of key machine parameters on the winding ac losses, including the excitation frequency, phase arrangement, conductor thickness, and PWM switching frequency.