High-speed electric machines are gaining importance due to their high power density. The evaluation of the mechanical stress in the rotor is a crucial part of the design process for this type of machines. It is insufficient to evaluate just the static mechanical stress at maximum speed. The dynamic mechanical stress between the state of standstill and maximum speed needs to be considered as well to ensure the high fatigue strength of the rotor. One criterion that is commonly used to analyze the dynamic load in a material is the Smith diagram. In this work, a new methodology is introduced to consider both, the dynamic and the static mechanical stress, in the rotor of a high-speed electric machine. First, the von Mises stress criterion is used to examine the static mechanical stress in the rotor core. Second, the Smith diagram is used to evaluate the dynamic mechanical stress and the high fatigue resistant of the rotor. The methodology is, then, applied to a high-speed electric machine with two different types of buried magnets: 1) a rotor with buried magnets in v-shape and 2) a rotor with a buried bar magnet. Both rotors are analyzed concerning their state of stress. It can be seen that high dynamic stress occurs at the bridges in the rotor. The stress alternates with an amplitude up to $\sigma _\text{alt}=290\,\text{MPa}$ . The designs are though limited due to the high static stress at the bridges of the magnet slot.

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评估具有埋地磁铁的高速电机中的机械应力的方法

高速电机因其高功率密度而变得越来越重要。转子中机械应力的评估是此类机器设计过程的关键部分。仅评估最大速度下的静态机械应力是不够的。还需要考虑静止状态和最大转速之间的动态机械应力，以保证转子的高疲劳强度。一种常用于分析材料动态载荷的标准是史密斯图。在这项工作中，引入了一种新方法来考虑高速电机转子中的动态和静态机械应力。首先，von Mises 应力准则用于检查转子铁芯中的静态机械应力。其次，史密斯图用于评估转子的动态机械应力和高抗疲劳性。然后，将该方法应用于具有两种不同类型的埋入式磁铁的高速电机：1) 具有 V 形埋入式磁铁的转子和 2) 具有埋入式条形磁铁的转子。分析了两个转子的应力状态。可以看出，转子中的桥接处出现了高动态应力。应力交替的幅度高达$\sigma _\text{alt}=290\,\text{MPa}$ . 但由于磁体槽桥处的高静态应力，这些设计受到了限制。