The axial flux motor without iron core hascompact structure, small size, light weight, high torque density,but poor thermal characteristics. Thermal research is a key stepin the design of axial flux permanent magnet motors withoutiron cores. In this paper, the temperature of the motor withoutiron core is predicted based on two-dimensional equivalentthermal network and coupling iteration. Firstly, the structureand working principle of the flywheel energy storage field aredescribed. Secondly, The system heat source is mainly dividedinto three parts, which are considered separately in the article.Thirdly, A two-dimensional thermal model suitable for vacuumpumping in flywheel energy storage systems was proposed andvalidated, and applied to its temperature prediction.

-Flywheel energy storage system; Axialmagnetic flux; Internal vacuum pumping; Two-dimensionalthermal model.