Cooling for Electric Aircraft Motors

This paper discusses an approach for thermal management of a smart electric motor for hybrid electric aircraft propulsion. This approach uses indirect liquid cooling because it is a lightweight and reliable method for transferring large amounts of heat. A cooling jacket is designed for the stator of the aircraft propulsion motor and its cooling performance simulated for 200 kW and 1MW motors. For a 200 kW motor, the cooling jacket as designed is sufficient to keep the motor below the maximum recommended operating temperature, but additional cooling is needed for a 1 MW motor. Two approaches are discussed to address this higher cooling requirement - 1) using tailored potting and insulation material to lower the internal thermal resistance, and 2) using a more advanced cooling jacket. Rotor cooling is also discussed in this paper. Rotors with light heat loading can be cooled by forced convection airflow; while those with heavy heat loading can be managed with an internal channel design. Two integration schemes of motor and power electronics are presented as well.