Effect of Rotor bar Shape and Stator Slot Opening on the Performance of Three Phase Squirrel Cage Induction Motors with Broken Rotor Bars

Abstract

Stator slot opening width has an impact on the airgap magnetic field, a poor choice of this design parameter can results in distorted airgap magnetic field and increased space harmonics. This will have a negative impact on the performance of three phase squirrel cage induction machine (SCIM). Changing the rotor bar shape also varies the resistance at different depths of the bar either increasing or decreasing the electromagnetic torque. The purpose of this paper is to investigate how both the stator slot opening widths and rotor bar shapes affect the performance of SCIMs that operate when healthy and when their rotor bars are broken. 2D Finite Element Method (FEM) is employed as a computational tool for modelling these SCIMs and the magnetostatic and transient analysis are carried out in order to study the torque, torque ripple, efficiency and power factor.