Thermal Measurement and Prediction of an Air-Cooled Induction Motor

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Liu, H-P.
Werst, M.D.

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Active cooling is typically required for continuously operated electric motors to prevent rotors and stators from overheating. Various motor cooling designs have been developed in the past to meet the needs and constraints for different motor applications. This paper presents thermal measurement and prediction of an induction motor which is an integral part of a large energy storage generator. The induction motor was designed to be cooled by unidirectional airflow ventilated across the air gap between the rotor and the stator. Transient rotor and stator temperatures have been measured for the described induction motor in a 2.87-hr thermal test. The energy storage generator was held at a constant speed of 3,500 RPM during the test, and the heat generation included windage, bearing, and motor electrical losses. Transient 3-D motor rotor and stator thermal analyses were performed using thermal and airflow parameters obtained in the test. Comparisons between the predicted and measured temperatures indicate the 3-D motor thermal modeling can provide relatively accurate thermal predictions.


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H-P. Liu, M.D. Werst, “Thermal Measurement and Prediction of an Air-Cooled Induction Motor”, IEEE International Electric Machines and Drives Conference, 2007, WITHDRAWN.