Optimization of hybrid cooling system and flow-thermal coupling analysis for high-speed magnetic bearing-motor system

In high-speed magnetic levitation motors, coupled heat generation from copper, iron, and windage losses significantly compromises operational stability. To address this issue, this study proposes a comprehensive multi-domain hybrid thermal management strategy for magnetic bearing-motor system. A multi-physics approach combining electromagnetic loss analysis and three-dimensional fluid-thermal computational fluid dynamics was employed. To mitigate severe thermal accumulation, structural optimizations were conducted from three aspects: (1) staggered water-cooling baffles were designed to eliminate flow stagnation, reducing the maximum local temperature from 38.74 °C to 28.23 °C without inducing an additional pressure penalty; (2) a dual inlet-dual outlet airflow structure was investigated to avoid a drop in downstream cooling, thereby decreasing the downstream bearing temperature from 41.4 °C to 27.8 °C; (3) the normal angles of the bearing ventilation holes were optimized to a range of 15° to 30° to prevent boundary-layer airflow separation, yielding a further 9.34% local temperature reduction. Consequently, the optimized hybrid system restricted rotor thermal deformation to a highly safe margin of 0.0035 mm. Validated by physical experiments with an average relative error of merely 1.35%, this study provides robust quantitative design guidelines for mitigating narrow-gap flow resistance and heat stagnation in magnetic bearing-motor systems.