Comparison of Interior Permanent Magnet Machine Designs Aimed for City and Highway Driving - Consequences on Loss and Torque Performance from Degradation Due to Laser Cutting

Paper i proceeding, 2025

This paper explores four interior permanent magnet machine designs to assess the impact of cutting degradation on their loss and torque. Predicting the electric machines' core loss is important for achieving a viable design. However, existing theoretical models for calculating core loss do not consider the degradation of electromagnetic properties in electrical steel sheets from manufacturing processes. Instead, constant empirical factors are introduced to bridge the gap between theoretical analysis and test results. The important key findings of this study indicate that designs with more stator slots are more susceptible to increased core loss, for instance moving from 48 slots to 72 slots can cause up to 20 % higher core loss increase due to cutting while the same would cause 0.5 % higher torque reduction. However, adding more magnet layers in the rotor, hence, increasing degraded cut edge area has minimal impact on core loss and only reduces torque production by 1 %.