Abstract
This work analyses the effect of different rotor bar shapes and stator slot opening of a three phase induction motor operating under healthy and broken rotor bar fault conditions. Due to symmetrical nature of the machine, and the omission of end winding flux leakages in this work, the three phase squirrel cage induction motor (SCIM) is designed and modelled using the two dimension (2D) finite element method (FEM). The magnetostatic solver is used to obtain the flux density distribution under different operating conditions, while the instantaneous torque, torque ripple, power factor, efficiency etc., are computed using the AC magnetic transient solver.
For qualitative and quantitative evaluation of the effect of rotor bar shape and stator slot opening width on the performance of three phase SCIMs, the Analysis of Variance (ANOVA) assisted by Finite Element Analysis (FEA) is used, for single and multi-factor analysis. In both single and multi-factor analysis, a two-way ANOVA is used together with FEA to assist analysing the level of significance that the design parameters have on the performance responses of the three-phase SCIM under healthy and broken rotor bars.
From the FEA results, it is evident that the rotor bar shapes and stator slot openings have a significant influence on the airgap conductance and flux density distribution of the three-phase squirrel cage induction motor (SCIM). A change in rotor bar shape results in varying the rotor bar parameters, and this has a significant impact on certain performance indexes of the SCIM, such as the torque, efficiency and power factor.
Furthermore, the FEA results also evidenced that the electromagnetic torque profile is affected when there is occurrence of a broken rotor bar, therefore introducing a number of unwanted torque harmonics. The latter contribute to torque ripple production in the three-phase SCIM...
M.Tech.