This paper presents an accurate modeling method to investigate the thermal performance of the windings under steady state. The model considers the heat conduction of active windings and heat convection of end windings. To verify the validity of this model, a 20/24 poles/slots permanent magnet (PM) in-wheel motor is taken as an example. Firstly, the temperature distribution of the active windings in the slot is calculated by a multi-block 2-D temperature field model, which is verified by the model built according to the reality. The numerical results of blocks model agree well with those of the real model. Secondly, a 3-D temperature field model with the end windings is built on the 2-D blocks model. Furthermore, to include the air inside the motor, computational fluid dynamics (CFD) has been utilized, and the numerical results are experimentally verified. Finally, the distribution of the heat transfer coefficient (HTC) of the end windings and the influence of rotor speed on the HTC are investigated. These HTCs acquired from CFD results and empirical formulas are compared and analyzed carefully.

中文翻译：

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基于多块法的封闭式永磁同步轮毂电机主动绕组和端绕组热建模与分析

本文提出了一种精确的建模方法来研究稳态下绕组的热性能。该模型考虑了有源绕组的热传导和端部绕组的热对流。为验证该模型的有效性，以一台20/24极/槽永磁（PM）轮毂电机为例。首先，通过多块二维温度场模型计算槽内有源绕组的温度分布，并通过根据实际建立的模型进行验证。块体模型的数值结果与真实模型的数值结果吻合较好。其次，具有端部绕组的 3-D 温度场模型建立在 2-D 块模型上。此外，为了包括电机内部的空气，已利用计算流体动力学 (CFD)，并对数值结果进行了实验验证。最后，研究了端部绕组传热系数（HTC）的分布以及转子速度对传热系数的影响。这些从 CFD 结果和经验公式中获得的 HTC 进行了仔细比较和分析。