Thermal model for induction machine

This paper presents a thermal circuit model to simulate the behaviour of an electric motor during the transient duty leading to steady-state operation under rated load. The proposed model allows the calculation of the temperature distribution in the radial direction of the electric motor, from the shaft inside to the motor frame surface. Several heat sources inside the motor as well as the heat conduction and the thermal contact resistances have been considered. The surface convection heat transfer inside the motor and at its external surfaces is modelled by using heat transfer coefficients. Due to its flexibility and ease of implementation, the software MATLAB SIMULINK was used as the platform for modelling and simulation. The simulation points out the importance for a correct modelling of internal heat generation and contact resistances in order to predict the transient behaviour.