Thermal analysis of a high-speed PM machine using numerical and thermal-network method

Different methods for thermal analysis of a high-speed permanent-magnet machine are presented. The first implemented method is a numerical method which couples computational fluid dynamics and heat-transfer equations. This method gives simultaneous solutions for the thermal and turbulent properties of the cooling fluid in a 2D axi-symmetric geometry and a 3D solution of the temperature distribution in the solid domain of the machine. This method uses the properties of the turbulent flow from the 2D model such as the temperature rise of the fluid and the coefficients of thermal convection and implements them in the boundary conditions of the 3D model. The traditional thermal-network method that is based on analytical and empirical equations is also implemented in this paper and its results are compared with the results of the numerical method. The aforementioned methods are validated with measurements using thermocouples at different spots of the stator winding.