The fan design impact on the rotor cooling of axial flux permanent magnet machines

Thermal management of Axial Flux Permanent Magnet (AFPM) machines is essential because it determines the machine's continuous power output and reliability. Also, thermal management is required to avoid catastrophic failure due to degradation. To help meet this challenge, a secondary cooling method can be integrated into the rotor, which can yield improved machine performance and reliability. Thermal analysis via Lumped Parameter (LM) networks is usually sufficient in predicting the thermal motor behaviour. Accuracy can be further increased with the help of Computational Fluid Dynamics (CFD), especially for devices with complex flow regions. In this paper, the fan blade was attached to the rotor of a YASA machine for flow validation, and then three different fan blade designs from other engineering applications were adopted, in order to compare the flow characteristic, power requirement and thermal characteristic for AFPM cooling applications.