燃料电池车用超高速空压机永磁体结构强度研究

针对大功率燃料电池系统高速空压机转子永磁体离心拉应力破坏,采用解析法计算了额定转速时护套与永磁体间过盈量的大小及应力,采用有限元方法建立二维轴对称模型,计算了永磁体和护套内的应力分布,对比解析法与有限元方法的准确性.基于有限元法研究了温升和护套材料对永磁体应力的影响,结果表明,解析法和有限元法计算的各应力的相对误差不超过2.5％,而影响因素中转速和温升均会造成永磁体应力的显著提升,需要增大过盈量对转子永磁体保护.碳纤维护套相比合金护套可以至少降低42.1％的永磁体应力,且在高温工况下的效果更为显著.降低转速、增大装配过盈量以及改善转子冷却均能有效优化结构强度,而复合材料护套相比钢护套更适用于保护永磁体.

Study on Mechanical Strength of Permanent Magnetfor Super High-speed Air Compressor in Fuel Cell Vehicle

Aiming at the centrifugal tensile stress failure of permanent magnets on the rotor for super high-speed air compressor in high-power fuel cell system, the magnitude of interference between the sleeve and the permanent magnet as well as the stress at the rated speed are calculated by the analytical method. Then, a two-dimensional axisymmetric model was established by the finite element method to calculate the stress distribution, and the accuracy of the analytical method and the finite element method was compared. Furthermore, the influence of temperature rise and sleeve material on stress is studied based on the finite element method. The results show that the calculations of the two methods differ no more than 2.5%. Among the influencing factors, both the rotational speed and the temperature rise cause a significant increase in the stress of the permanent magnet, and it is necessary to increase the interference in order to provide protection for the permanent magnet. Additionally, the carbon fiber sleeve can reduce the stress of the permanent magnet by at least 42.1% when compared with the alloy sleeve, and the effect is particularly obvious under high temperature conditions. Therefore, reducing the rotating speed, increasing the assembly interference and improving rotor cooling can effectively optimize the structural strength, and the composite material sleeve is more suitable for protecting permanent magnets than the steel sleeve.