Analysis and design of AC induction motors with squirrel cage rotors

The traditional approach to modelling the AC induction motor revolves around the well-known equivalent T circuit model. In this approach, the direct connection from geometry to performance is suppressed. For better understanding of magnetic, electrical, and thermal behaviors, three lumped models based on the actual geometry are developed in this dissertation. Based on these lumped models, an iterative design model is also developed. In order to analyze and design induction motors, the relationships of basic motor variables to motor performance must be known. For determining the relationships, three new mathematical lumped models are developed. The magnetic model describes flux behavior. The electrical model, which is similar to the equivalent circuit model, is used to derive simple closed-form expressions of performance. The thermal model describes the effect of heat generation on temperature. The traditional approach of modelling the induction motor using the finite element analysis (FEA) is through the equivalent circuit model. Three new FEA methods are developed in this dissertation to calculate motor performance directly from the finite element field solution. The equivalent circuit model is no longer needed. The developed lumped models and FEA methods are applied to two commercial induction motors. Calculated performance is shown to closely match experimental results. The developed iterative design model is then utilized to design an induction motor for desired requirements. The motor is fabricated and calculated performance is also shown to closely match the experimental results