Logistic-Function Shaping of Radial Force for Acoustic Noise Reduction in Switched Reluctance Motor

In this paper, radial-force shaping using the logistic function is proposed for acoustic noise reduction in switched reluctance motors. The proposed radial-force shaping regulates the radial force on each stator tooth to track a logistic function with respect to rotor position. The logistic function is characterized by rising from zero to a constant value. This feature is used to define the radial-force references for the three phases so that their summation is always flat. By flattening the radial-force sum, the method effectively eliminates the multiples of the third component of the stator-tooth radial force. These components excite stator vibration in the form of mode 0. Consecutively, the proposed method significantly reduces the vibration and acoustic noise associated with mode 0. Furthermore, torque ripple is minimized through numerical sweeping involving only two parameters within a restricted search space. Experimental validation and finite element analysis confirm the effectiveness of the proposed method.