Thermal Investigations of Air-Cooled PMSM used in Full-Electric UAV

The problem of the motor cooling in electric aircraft propulsion is analyzed. In particular, the possibility of using forced convection cooling with external air flow is investigated. By approximating the heat exchange of an electric motor with the heat exchange of a semi-infinite thin plate immersed in an airstream, the effects of altitude on temperature and pressure are introduced into the thermal model. By solving the model in a specific range of altitude and aircraft speed variations, the change in the heat transfer coefficient on the motor surface is determined. These values are used for calculating the maximum temperature in a test motor by means of finite element analysis.