Radial Force and Acoustic Noise Reduction for Switched Reluctance Motor with Hole inside Pole

Abstract

A switched reluctance motor (SRM) has a simple construction, for example double saliency, and the rotor contains no windings or magnets. However, the disadvantage of the acoustic noise associated with this motor cannot be ignored.The acoustic noise is generated primarily by the radial force acting in the radial direction. As the excitation current is cut off, the radial force is suddenly reduced to 0. The stator yoke repeats attraction and release motion as the commutation at the excitation winding is repeated. This attraction and release motion excites the resonance frequency of the stator.In this paper, a new rotor pole structure is proposed to improve the acoustic noise of the SRM. The FEM analysis of the torque and radial force indicates that the presence of a hole in the rotor pole reduces the radial force. In addition, the effect of the radial force reduction was found to depend only slightly on the height of the hole, whereas the dependence on the width of the hole was significant.Experimental findings confirmed that a rotor pole having a hole is an effective method by which to improve the noise.