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Stator slot skewing and rotor step-skewing methods are the most commonly used methods to reduce the torque ripple and electromagnetic vibration in the electric vehicle (EV) drive motor industry. However, these two methods have limitations on the suppression of the 0th-order vibration component and multiples of rotor magnetic pole number order vibration components. This article presents a novel rotor-segmented motor with different pole widths to reduce electromagnetic vibration for EVs. The principle of the presented new rotor segmented motor to mitigate the 0th-order and the multiples of rotor magnetic pole number orders vibration components are analytically analyzed and illustrated. Three multiphysics field models, i.e., conventional motor, rotor step-skewing motor, and the presented motor, were established. The electromagnetic vibration properties related performances, including air-gap flux density, radial force, torsional force, and vibration response, are extensively compared. Finally, the rotor step-skewing motor and the presented motor were prototyped, and extensive tests were conducted. The results show that the presented motor has a specific mitigating effect on electromagnetic vibration, with a significant decrease in the 0th-order vibration amplitude and the overall vibration level is the same as that of the rotor step-skewing motor.

Interior permanent magnet machines (IPMSMs) have attractive features, including high power density, high efficiency, and excellent control performance. However, the unsuppressed torque ripple of IPMSM will cause declined torque quality, increased vibration, and reduced reliability. This article presents a novel composed T-shaped notching rotor to suppress torque ripple for IPMSM. The mathematical models of cogging torque and winding factors considering T- shaped notches are established, respectively. Although the principle of the novel rotor design is clearly explained by mathematical models, the accurate dimensions of the composed T-shaped notch are difficult to calculate. Therefore, two-dimensional finite element analysis and multiobjective design optimization are employed to calculate the T-shaped notch dimensions. The electromagnetic performance of the proposed rotor machine is compared with that of the commonly notching rotor machine. In addition, the mechanical strength of the novel rotor is verified by calculations of stress and deformation. Finally, the proposed prototype with a novel rotor is fabricated, and extensive experiments are conducted. The results show that the torque ripple of IPMSM can be significantly reduced by the novel composed T-shaped notching rotor.