Abstract:
Torque ripple and vibration are two leading limiting factors for interior permanent magnet (IPM) machines using in electric vehicles (EVs). At present, the skewing slots and segmented rotor methods are favored by EV traction motor manufacturers. These two methods are comprehensively analyzed and compared to provide technical reference for the torque ripple and electromagnetic vibration suppression of high-performance EV permanent magnet motors, especially IPM machines. Extensive performance comparisons in terms of cogging torque, back-EMF, reluctance torque, and instantaneous torque, are carried out. Besides, multi-physical field coupling models are established to compare the vibration properties including exciting force, modal frequencies, and vibration response. Finally, the skewing slot machine and segmented rotor machine are prototyped, and extensive experimental tests are done to verify the validity and reliability of the analysis and comparison. The research results indicate that the segmented rotor machine can achieve the same force quality as that of the skewing slot machine and greatly reduce the electromagnetic vibration. Besides, the application of the segmented rotor approach is not limited by the axial length, and it has a lower processing cost.