Calculation of Continuous Power Curves for Electrically Excited Synchronous Machines with Air Cooling

In this paper, a thermal model for the rotor of a salient pole synchronous machine is developed. Due to air flow through the active part of the electrical machine, a direct cooling of the field winding is achieved. The calculation of the thermal resistance between coil sides and cooling fluid is presented as well as a homogenization approach for simplifying the actual distribution of conductors and insulation material. The presented lumped parameter model is used to calculate the continuous power characteristics of an example machine.