Eccentricity and Stress Analysis in a Reluctance Motor with Finite Element Method

With the spread of synchronous electrical machines in many industrial applications and vehicle electrification, reluctance motors usage is becoming more relevant. The lack of permanent magnets and their reliability are making them a suitable choice in high speed and torque applications. Besides, because of the rotor configuration made of thin air barriers, noise and vibrations can represent a mechanical drawback. The main source of mechanical vibration is the radial stress due to bearing misalignment and eccentric condition of the shaft. In this thesis the stress at the surface of the stator is computed by means of electromechanics quantities such as radial forces and induction. The computations have been made for different orders of eccentricity. The simulations have been performed with finite element analysis, with FCSMEK software, developed in Aalto University. Therefore the stress frequency domain has been computed in a time-step analysis, with respect to different modes of distribution along the stator surface (modal analysis). Every distribution shows changes in amplitude with the increasing of the eccentricity order. All the quantities have been studied in a Fourier frequency domain to better understand their behaviour and to possibly predict the most significative ones. A clear match between radial forces and stresses is underlined respectively in the frequency domain. Finally the different stresses distribution are analyzed in comparison to the increasing of the eccentricity level.