High power-density electric machines present the benefits of high torque and speed. However, this generally comes with heating problems characterized by high temperatures that affect performance. Conventional approaches to address overheating are to include cooling fans or jackets within the stator core of the machine. This approach is challenging to implement in small-size high power-density machines. In this article, a cooling mechanism integrated in the rotor of a high power-density permanent magnet motor is proposed. It comprises a set of six holes, shrouded within a hollow shaft. The mechanism is based on conditioning air due to a centrifugal force that is produced by the rotational speed of the rotor from the inlet. A theoretical model based on flow resistance network is proposed to analyze the airflow rate. An analytical thermal model based on lumped parameter thermal network is developed to analyze the effect of the flow rate on the temperature distribution in the motor. Also, a simulation analysis model was conducted using computational fluid dynamics to analyze the effect of air flowing in the motor. An experimental prototype is developed to verify, validate, and evaluate the proposed cooling model. The cooling system is effective in reducing temperatures from speeds above 6000 min ⁻¹ .

中文翻译：

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高功率密度永磁电机气流冷却机制

高功率密度电机具有高扭矩和高速度的优点。然而，这通常会带来以影响性能的高温为特征的加热问题。解决过热问题的传统方法是在机器的定子铁芯内安装冷却风扇或护套。这种方法在小型高功率密度机器中实施具有挑战性。在本文中，提出了一种集成在高功率密度永磁电机转子中的冷却机构。它由一组六个孔组成，覆盖在空心轴内。该机构的原理是利用入口处转子转速产生的离心力来调节空气。提出了一种基于流阻网络的理论模型来分析气流速率。开发了基于集总参数热网络的分析热模型来分析流量对电机温度分布的影响。此外，还使用计算流体动力学进行了仿真分析模型，以分析电机中空气流动的影响。开发了一个实验原型来验证、验证和评估所提出的冷却模型。冷却系统可有效降低速度高于 6000 min ^-1的温度 。