Numerical investigation of heat transfer for high-speed permanent-magnet machine with spiral-duct rotor

The thermal behavior of high-speed permanent magnet (HSPM) machine is essential since overheating of the permanent magnets can lead to demagnetization. A novel rotor cooling structure with spiral-duct air cooling was presented for a 100kW, 60000rpm HSPM machine. The mathematical and physical model of coupled 3D fluid flow and heat transfer was established according to structure characteristic of machine. The governing equation of coupled fluid-flow and thermal field was calculated using finite volume method by giving fundamental assumptions and corresponding boundary conditions. Finally, the performance of fluid flow, characteristic of heat transfer, and temperature rise distribution of machine were analyzed in detail.