Dynamic Model of A 3-Phase Induction Motor for Thermal Analysis for Improving Performance

Abstract

This study presents a comprehensive dynamic model of a three-phase induction motor integrating electromagnetic and thermal domains for enhanced performance evaluation and reliability improvement. The electrical subsystem is formulated in the synchronously rotating dq-reference frame using coupled stator rotor voltage equations, flux linkages, and electromagnetic torque expressions derived from space-vector theory. The mechanical dynamics are represented through the rotor motion equation, considering load torque disturbances and inertia effects. To enable accurate thermal assessment, a lumped-parameter thermal network (LPTN) is developed, incorporating stator copper losses, rotor copper losses, core losses, mechanical losses, and stray load losses as heat sources. Temperature-dependent variations of resistance and material properties are included to capture electro-thermal coupling effects under transient and steady-state operating conditions. The integrated model enables the prediction of temperature rise in critical components such as stator windings, rotor bars, and core laminations during dynamic events, including startup, overload, and fluctuating load conditions. Numerical simulations demonstrate that incorporating thermal feedback into the electromagnetic model improves accuracy in efficiency estimation, torque prediction, and loss distribution analysis. Results further show that optimized cooling strategies and appropriate material selection significantly reduce hotspot temperatures, thereby enhancing insulation lifespan and overall motor reliability. The study reveals that asymmetrical thermal flow leads to localized overheating, increasing winding resistance, reducing efficiency, and accelerating insulation degradation. Temperature variations of 74.7°C, 76.7°C, 88.7°C, and 86.5°C were recorded in different motor sections, with an acceptable thermal range of 10°C to 40°C. Optimized cooling mechanisms and material selection significantly reduce these effects, enhancing motor efficiency.