Study of torque ripple and noise for different rotor topologies of a synchronous reluctance machine

The use of electric machines as traction in electric vehicles raises the concern of the vibration and the noise level generated by the structure. Radial forces in the stator of electrical machines have a high contribution to these vibrations. This paper presents a coupled finite element method (FEM) for calculating the radial force, torque ripple and predict the acoustic noise in synchronous reluctance machines (SynRMs). The knowledge of the modal parameters of the stator structure (mode shapes and natural frequencies) and the frequency spectrum of the radial magnetic force can be effectively used to design SynRMs with minimal noise through geometrical design variations at an early stage. An automatic process has been developed for designing a synchronous reluctance machine, to enable faster implementation of the geometry modifications and investigation of electromechanical properties while regarding also the problems related to noise. The practicality of the automation is demonstrated on modifying the rotor geometrical design for a SynRM that would apply for traction of small electric vehicles. The effect of the stator geometry or winding distribution on acoustic noise can also be analyzed with the model presented in this paper.