Investigating Impact of Rotor Slot Design on Torque of Medium Rated Squirrel Cage Induction Motor

Abstract

The modeling of the rotor of a mediumrated squirrel cage induction motor depends on the design parameters of the rotor slot, which control the overall performance characteristics of the motor. Among all performance measures of induction motors, rated torque takes important attention because it is the key measure determines the characteristics of the induction motors. Variation of rotor slot geometries affects the resultant resistance and reactance of the rotor, which highly impact the losses, output power, and speed characteristics. In this research work, a parametric study on three rotor slot parameters, namely, rotor slot depth (Hr), rotor slot opening height (Hor), and rotor slot tooth width (Btr), is carried out by using an analytical model of squirrel cage induction motor. A medium-rated general-purpose squirrel cage induction motor with 7.4 hp, 60 Hz, and 460 volts is modeled in the MATLAB software platform. Developed analytical model of induction motor is further validated with Ansys Electronics Desktop finite element modelling software platform. The dependency of each parameter on rated torque is tested as a two-dimensional plot, which has been extended into a four-dimensional scatter plot. From the individual and four-dimensional plots of the motor obtained through the simulation of the motor model in the MATLAB software environment, it has been proven that rotor slot parameter modelling has a high impact on the rated torque of the medium-rated induction motor.