含卸荷槽的高速永磁电机转子强度分析

Rotor Strength Analysis of High Speed Permanent Magnet Motor with Unload Slot

兆瓦级高速永磁电机转子多采用表贴式永磁体分块结构,在服役工况下永磁体易产生应力集中,导致局部应力过大。因此,以1台1.12 MW、18000rpm的高速永磁电机为例,采用有限元方法对不同隔磁材料的永磁转子结构进行强度分析,研究隔磁材料对永磁体和护套应力的影响,提出了隔磁件开卸荷槽的方法,以减小永磁体的应力集中现象。设计3种不同卸荷槽形式,通过应力分析确定最佳结构形式及尺寸。结果表明,隔磁材料特性对永磁体径向应力及护套切向应力影响较大,合理的卸荷结构可有效降低永磁体的集中应力。

The surface-mounted permanent magnet(PM)block rotor structure is used for megawatt high-speed permanent magnet motor(HSPMM).Under service conditions,the PMs are prone to produce edge effect that probably lead to local stress concentration.To solve the above problems,the strength analysis of PM block rotor structure with different magnetic isolation materials is carried out by the finite element method for a 1.12MW,18000r/min HSPMM.The effect of magnetic isolation materials on the stress of PM and sleeve was investigated.The rotor structure with unloading slot was proposed to reduce the edge effect of PMs.Three different unloading structures were designed and the optimum structure and size were determined by stress analysis.The results show that the properties of magnetic isolation materials have a great influence on the PM radial stress and the sleeve tangential stress.A reasonable unloading structure can effectively reduce the concentrated stress of PMs.