Cogging torque sensitivity considering imperfect magnet positioning for permanent magnet machines of different slot and pole count

Abstract

This work is about analyzing surface mounted permanent magnet machines regarding their sensitiveness related to erroneous magnet positioning. A finite element analysis based approach is presented and different topologies in terms of slot and pole count are compared. The study further includes the analysis of multiple magnet widths and stator teeth widths. By contrast to most of previous studies, the work is based on evaluating the cumulative distribution function of the cogging torque in case of non-idealities. A Monte Carlo importance sampling based strategy is focused. This approach facilitates studying arbitrary tolerance distributions. Results reveal that topologies with particularly promising rated cogging torque behaviour exhibit the most significant performance degradation in presence of tolerances. A linear relationship is identified for cogging torque performance as function of the accuracy in magnet positioning. Results emphasize the necessity of tolerance analyses for electric machine design to not overrate their performance in the presence of manufacturing uncertainties.

Keywords

• cumulative distribution function
• electric machine
• monte carlo
• pmsm
• quantile
• sensitivity
• tolerance analysis