Evaluation of Tooth Forces of Skewing Configurations of Permanent Magnet Synchronous Machines regarding Rotor Eccentricities in 2D and 3D FE simulations

This paper presents different skewing configurations for a permanent magnet synchronous machine and the resulting stator tooth forces due to static and dynamic rotor eccentricities in the torque-speed characteristics diagram. Since the noise emitted by an electrical machine due to high frequency pure tones has an important influence on the Noise Vibration Harshness (NVH) behaviour of a vehicle, it is necessary to determine possible fault patterns. For this purpose, a simulation routine by combining electromagnetic simulations using the Maxwell Stress Tensor (MST) and structural dynamic simulations were used. The resulting deformations, velocities and surface accelerations of a simplified model are used to evaluate the effectiveness of step skewing. Additional 3D finite-element (FE) simulations show that axial forces occur at the transition point between two magnetic segments of a skewed rotor.