“…However, when the motor works, torque ripple that causes vibration and noise will occur, including cogging torque ripple, commutation torque ripple. 22,23 Cogging torque ripple is related to the structure of the motor, such as the least common multiple of slots number and poles number, slotted type, arc coefficient, the inclination angle of the slot and the rest. 24,25 Figure 7 shows the composition of the electromagnetic propulsion part which converts electrical energy into mechanical energy.…”