Multiphysics Research and Loss Calculation Considering the Fluid Regime of the Airgap Based on High-Speed PMSM

This paper focuses on the calculation of different kinds of mechanical loss and put forward a complete method to calculate the mechanical loss for high-speed PMSM accurately. Windage loss, bearing loss, and cooling fan loss are calculated concretely, and the flow regime of the airgap is analyzed for windage loss calculation. Then, the equivalent thermal conductivity of the airgap in the turbulent regime is calculated, and it turned out to be much larger than that of stationary air, which cannot be ignored in high-fidelity modeling. Later, the two-way electromagnetic-thermal coupling method is applied in the multiphysics design. The results show the flow regime of the airgap cannot be neglected in windage loss calculation, and the mechanical loss calculation method put forward in this paper is more complete than previous research. Therefore, it can predict the electromagnetic-thermal performance of high-speed PMSM more accurately.