Electromagnetic Performance Characterization of 4-Pole Squirrel-Cage Motors with different Rotor Slot Combinations

In this study, the influence of number of rotor slots on the electromagnetic performance characteristics of three-phase, four-pole squirrel-cage induction motor (SCIM), such as efficiency, torque, power factor torque ripple, and losses are studied using the finite element method (FEM). Firstly, classical design equations are used to obtain geometrical parameters of the SCIM before simulating the five SCIMs with FEM. The SCIMs are designed by using the same winding layout, stator outer diameter, stack length, rated power of 7. 5kW and rated speed of 1460 rpm. The rotor slot count varies from 36 to 59, and the standard SCIMs have 48 stator slots. According to the simulation results, there is a rotor slot number at which the highest possible power factor, torque, and efficiency are attained, together with the least amount of torque ripple and losses. It is observed that stator/rotor slot combinations of 48/36, 48/40, 48/57, and 48/59 exhibit torque ripples of 4.15%, 4.40%, 4.60% and 4.65%, respectively, while 48/44 recorded the highest ripple of 6.44%. Nevertheless, SCIMs with 48/44 and 48/59 stator/rotor slot combination recorded the highest (89.31%) and lowest (86.9%) efficiency at the rated condition. Based on the needs of the industrial applications, these insights can be applied to the design of three-phase SCIM.