3D FEA based squirrel cage rotor model for design tradeoffs and performance analysis

An accurate rotor resistance estimation model of squirrel cage induction motors (SCIMs) is developed in 3D FEA. 2D transient analysis was utilized for excitations in the 3D model to improve its accuracy over previous 2D and analytical methods. Rated and starting performance from the FEA model match with the nominal and locked-rotor performance of a 3-phase, 460 V, 1 hp test machine. A modified ring model has been proposed and machine torque-slip characteristics and nominal performance have been analyzed. The effect of slot opening and 4 classes of SCIM bar geometry have been investigated to analyze their relative performance. Finally, four different ring and bar combinations are suggested, with the modified rotor structure presenting gain in starting and rated performance compared to the test machine. Results present the design tradeoffs and performance analysis, first for a 1 hp SCIM and then extended for a higher power (10 hp) machine.