Tolerance Study to Forecast Performances of Permanent Magnet Synchronous Machines Using Segmented Stator for Mass Production

This research provides a detailed analysis of the effect of build variations for mass produced permanent magnet synchronous motors on key performances such as torque ripple, back EMF harmonics, and torque/speed. The study defines the rule for worst case scenarios, hence providing tolerance limits for each of the design dimensions/parameters to be controlled to achieve desired performances in mass production. The research also sorts out the sources of each torque ripple order, hence identifying the design dimensions to be controlled. A finite element based electromagnetic simulation is used for the tolerance study and effectively used for defining practical limits for key design dimensions/parameters, without significantly impacting the yield rate or cost. The motors have been built and tested to verify the design guidelines. The test showed strong correlation, justifying the values of such study before launching mass production to meet the target yield rate.