Vibration Reduction by Magnetic Slot Wedge for Rotating Armature Permanent Magnet Motors

There is only slot frequency electromagnetic vibration and no pole frequency vibration in rotating armature permanent magnet motor (RAPMM), which is the advantage of this motor. The open of slot makes the air-gap magnetic field distorted and causes the harmonic of electromagnetic excitation force. In order to reduce the slot frequency vibration of the RAPMM, the method of placing magnetic slot wedge (MSW) at the slot opening is put forward accordingly. Through the finite-element simulation, it is finally shown that the MSW is capable of weakening the harmonic of the air-gap flux density, as well as decreasing the high-frequency component of the electromagnetic excitation force. Therefore, it is acknowledged that MSW can suppress the cogging torque and the vibration of corresponding frequency on the stator significantly. Finally, it is confirmed by the experiments that the built-in MSW is an effective measure for reducing the vibration of the RAPMM.