Optimizing Squirrel Cage Rotor Design: Combined Effects of Bar Inclination and Intermediate Rings

Abstract

This study investigates the combined effects of bar inclination and intermediate rings on squirrel cage rotors in three-phase induction motors. Through Finite Element Method (FEM) simulations and extensive laboratory tests, four rotor configurations were analyzed: straight bars without an intermediate ring, inclined bars without an intermediate ring, straight bars with an intermediate ring, and inclined bars with an intermediate ring. The results demonstrate that incorporating inclined bars improves torque smoothness and reduces noise levels, with a reduction from 75 dB in Rotor 1 to 60 dB in Rotor 4. However, this improvement comes at the cost of increased Joule losses, rising from 9.37 W in Rotor 1 to 23.84 W in Rotor 2. The addition of intermediate rings further enhances current distribution and reduces harmonic currents, with Rotor 4 showing the best performance in terms of the lowest slipping percentage (2.90%) and stable torque output. Despite these gains, intermediate rings also lead to higher core losses, with an increase to 113.49 W in Rotor 4. The study highlights the trade-offs between performance improvements and efficiency losses, suggesting that future optimizations must focus on balancing these factors. The findings have practical implications for industries requiring high-performance, low-noise motors, such as Heating, Ventilation, and Air Conditioning (HVAC) systems and precision manufacturing. This research provides actionable insights into optimizing rotor design for specific industrial applications by reducing harmonics, improving torque smoothness, and managing associated losses.