Transient 3-D thermal analysis for an air-cooled induction motor

For an induction motor that is cooled by an airflow ventilated across the air gap between the rotor and stator, the rotor end-ring and stator end-turn cooling might influence the motor temperatures in the core sections appreciably. Detailed motor thermal modeling is typically required to provide transient rotor temperature distributions for rotor structural analysis and to predict stator temperature distributions to assure the maximum stator temperature is below the stator insulation temperature limit. For an air-cooled induction motor, transient 3-D finite element thermal analyses for both rotor and stator have been performed in this paper. In the stator thermal model, the slot conductors and various insulations were smeared and equivalent thermal properties were used to reduce modeling and computational effort. Position-dependent and time-dependent air cooling boundary conditions, which include air temperatures and forced convection heat-transfer coefficients, were applied to the 3-D thermal models