Advances in Quality Monitoring of Stray Fields on Rotors of Permanent Magnet Synchronous Motors

For industrial applications and as traction drives for electric cars, permanent magnet synchronous motors are widely used. They are characterised by excellent dynamic operating behaviour with very good controllability and power density. However, their quality characteristics are influenced by deviations due to material and production variances. One approach for quality control can be the monitoring of the stray field of the rotor magnetic field before joining the rotor into the stator. In doing so, rotor deviations can be detected and effects on the overall motor be predicted, e.g. fluctuations of the power or increased cogging torques. In this paper, the application purposes and restrictions of this monitoring approach are shown. A special focus is set on presenting the current development status of the rotor test bench, which has already been presented in earlier work. In this context, a calibration method for hall sensor arrays is introduced to further improve the quality assurance in rotor production. By integrating a laser distance sensor into the measuring setup, a better localization of deviations can be achieved.