Metallic sleeves are widely used to ensure the mechanical integrity of rotors in high-speed permanent magnet (PM) synchronous machines (HSPMSM). However, in traditional high-speed rotors, the PMs which are very weak in tensile stress cannot be well protected by sleeves. Furthermore, the material properties of both the sleeves and PMs cannot be fully used. As a result, the high-speed running range of the machines are limited by the mechanical strength for a given rotor size. In this paper, taking a 230-kW 35-kr/min prototype as an example, the mechanical strength issues of the rotor are investigated by analytical method and finite element analysis (FEA). In order to overcome the unbalanced protective effect of the sleeve and make fully use of the materials, an optimal sleeve, as well as an improved rotor structure, is presented. The comparison results show that the optimized sleeve has well balanced protective effect to the PM as well as good utilization of materials, with a resultant increase in maximum speed of nearly 40% with respect to the prototype.

中文翻译：

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高速永磁同步电机金属套的机械强度分析与优化

金属套筒被广泛用于确保高速永磁（PM）同步电机（HSPMSM）中转子的机械完整性。但是，在传统的高速转子中，拉伸应力非常弱的PM不能用套筒很好地保护。此外，套筒和PM的材料特性无法充分利用。结果，对于给定的转子尺寸，机器的高速运转范围受到机械强度的限制。本文以230 kW 35 kr / min的原型为例，通过分析方法和有限元分析（FEA）研究了转子的机械强度问题。为了克服套筒的不平衡保护作用并充分利用材料，提出了最佳的套筒以及改进的转子结构。