Switched reluctance motors (SRMs) are gaining in popularity because of their robustness, cheapness and excellent highspeed characteristics. However, they are known to cause vibration and noise primarily due to the radial pulsating force resulting from their double-saliency structure. This paper investigates the effect of skewing the stator or/and rotor on the vibration reduction of the three-phase SRMs by developing four 12/8-pole SRMs including a conventional SRM, a skewed rotor-SRM (SR-SRM), a skewed stator-SRM (SS-SRM), and a skewed stator and rotor-SRM (SSR-SRM). The radial force distributed on the stator yoke under different skewing angles is extensively studied by the finite element method (FEM) and experimental tests on the four prototypes. The inductance and torque characteristics of the four motors are also compared and a control strategy by modulating the turn-on and turn-off angles for SR-SRM and SS-SRM are also presented. Furthermore, experimental results have validated the numerical models and the effectiveness of the skewing in reducing the motor vibration. Test results also suggest that skewing the stator is more effective than skewing the rotor in SRMs.

IEEE Flux-switching permanent magnet (FSPM) machines are gaining in popularity due to their robustness, wide speed range, high torque, and high power density. However, their cogging torque leads to vibration and noise due to the double-saliency structure. This paper investigates the effects of the short permanent magnet (PM) and stator flux bridge (FB) on the cogging torque reduction of three-phase 12/10-pole FSPM machines. Four different FSPM machines, including the inner-inner topology, inner-outer topology, outer-inner topology, and outer-outer topology, are developed and analyzed with both short PM and stator FB. The configurations are obtained by placing the FB at inner/outer stator lamination and reducing the PM towards inner/outer axial directions. The cogging torque, average output torque, and PM utilization ratio of different topologies are extensively studied and compared by the finite element method (FEM). Finally, prototype machines are manufactured and tested. The experimental results have validated the numerical models and the effectiveness of the developed machine in reducing the cogging torque. The results also suggest that the outer-inner topology is more effective to reduce the cogging torque, which not only reduces the utilization of the PM materials, but also mitigates the cogging torque at only slight cost of machine performance

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