Innovations in Axial Flux Permanent Magnet Motor Thermal Management for High Power Density Applications

Abstract

For aerospace applications, power density is a major driving force in the design of electrified powertrains. At the forefront is the challenging design of electric motors with high efficiencies, torque, and power capabilities. Due to its high performance, the axial flux permanent magnet (AFPM) motor is expected to be one of the leading technologies to meet the demands of these industries. Finding the balance between the cooling system's effectiveness and subsequent parasitic losses is key to utilizing these performance benefits. Single-stator double-rotor topologies achieve the best torque density and lower stator losses and, however, are more challenging to cool as the stator is in the center of the motor. Single-stator single-rotor and double-stator machines are less challenging to cool but typically have lower power density. Rotor air cooling is discussed, including the effectiveness of blades, meshes, and vents, which can be optimized to prevent demagnetization. Stator cooling is critical as many machines maximize current density, producing a large amount of heat. The chosen strategy depends on the machine topology and can be accomplished by several strategies, including jackets, fins, channels, immersion cooling, hollow coils, and heat pipes.