Thermal evaluation of a propulsion motor for electric air-craft

The axial flux and the radial flux machine with concentrated winding are compared in an electric aircraft application. New materials for impregnating the windings are investigated thermally and the radial flux machine is investigated in a case with direct air flow cooling. The axial flux machine has higher relative amount of copper in the end windings and the copper losses are higher in this machine type. However the two rotor concept with a central stator without a yoke has lower core losses. An axial flux machine where the core losses dominate could have benefits compared to the radial flux machine. An impregnating material with the thermal conductivity of 1 W/mK results in only 35 degrees temperature increase over the core temperature of the winding, when the current density is 18.8 A / mm2. An example design of the machine is shown. The losses can according to the Comsol analysis be handled with free airflow the machine parts.