综合材料强度等因素的轴向电磁轴承最大承载力与转速关系分析

Analysis of the Relationship Between the Maximum Bearing Capacity of Axial AMB and the Rotational Speed Based on the Comprehensive Material Strength and Other Factors

高温气冷堆商业示范电站(HTR-PM)主氦风机转子重4吨、运行功率4.5MW,立式运行于氦气环境中,选用全电磁轴承支承。其中,轴向轴承设计要求能够承受转子重力4吨及同向叠加的气动载荷8吨。轴向电磁轴承电磁力与磁极(包括止推盘)面积成正比,取决于止推盘所允许的最大外径。但当考虑转速时,最大外径还受材料强度限制而不能任意选取。因此,在材料强度、最大外径(最大电磁力)与最高转速之间存在一定的函数关系,若综合考虑损耗及允许温升等因素,各个参量的关系相对更为复杂。本文根据第一强度理论,确定了转子极限转速与不同结构形式的止推盘最大外径的解析关系;进一步,通过电磁仿真分析验证了不同转速、不同材料对应的最大电磁力。并在上述分析计算基础上,基于专用1:1实验装置,对比推力盘所受电磁力随电流而变化的情况。研究结果有助于HTR-PM高温气冷核反应堆主氦风机轴向电磁轴承的选型设计。

The rotor of the main helium circulator in the High temperature gas cooled reactor commercial demonstration power plant(HTR-PM) weighs 4 t, and its operating power is 4.5 MW. It runs vertically in the helium environment and is suspended by AMBs. The axial magnetic bearing is required to bear the rotor 4 t, and the aerodynamic load superposed in the same direction, at least 8 t. The electromagnetic force of the axial AMB is proportional to the area of the magnetic pole(including the thrust disk).The maximum electromagnetic force depends on the maximum outer diameter allowed by the thrust disk. However, when the rotation speed is considered, the maximum outer diameter is also limited by the material strength and can not be arbitrarily selected. Therefore, there is a certain functional relationship between the material strength, the maximum outer diameter(maximum electromagnetic force) and the maximum speed. If the factors such as loss and allowable temperature rise are considered comprehensively, the relative relationship of each parameter is more complex.According to the first strength theory, the analytical relationship between the limiting speed of the rotor and the maximum outer diameter of the thrust disk with different structure is determined;furthermore, the maximum electromagnetic force corresponding to different speed and different materials is verified by electromagnetic simulation analysis. According to the above analysis and calculation and based on a special 1:1 experimental device, the electromagnetic force of the thust is analyzed, varing with different currents. The results of this article is beneficial to the type selection and design of the axial AMB of the main helium circulator in the HTR-PM.