A study on the torque ripple improvement of a BLDC motor via skewed magnet

This paper proposes a means to reduce torque ripple in a 2 poles, 30 (W) small size BLDC motor in radial blower. The BLDC motor have six times torque ripple interval per one period. This problem is the cause of noise and vibration that leads to the degradation of the output torque. For example, First, cogging torque is generated due to the reluctance difference of the teeth of the stator core for rotate time. It is the cause of noise and vibration that leads to the degradation of the performance. So, a plastic molding was used in order to reduce the cogging torque. The molding made the constant magnetic path between the stator and the permanent magnet thereby, reducing the cogging torque. Second, the torque ripple is generated due to a harmonic components of the magnetomotive force at the air gap difference. So a skewed permanent magnet was used in order to reduce the torque ripple. The validity of the thesis was proven via 2D, 3D FEA.