Online Thermal Monitoring Models for Induction Machines

This paper presents a new transfer function approach for calculating both the average temperature and hot spot temperature of an induction machine with the consideration of temperature-dependent material properties and speed-dependent heat transfer coefficient. Green´s functions are introduced and taken as the new transfer functions. Online thermal monitoring models for induction machines are obtained based on Green´s function method. Using the presented method, the hot spot temperature and average temperature can be calculated accurately and rapidly. The proposed method is validated via finite-element method and experimental measurement.