Litz wire has been widely used in high-frequency electrical machines and transformers to minimize induced current loss and maintain high efficiency. Its heat dissipation capability can be a key design factor for high-power-density, high-frequency electrical machines. Although litz wire equivalent thermal conductivity has been studied, its transposition arrangement on heat dissipation enhancement is usually neglected. This article focuses on developing an analytical model to predict litz wire equivalent thermal conductivity including transposition effects. 3-D finite element models and hardware experiments are used to validate the proposed analytical model. Fast and accurate litz wire thermal conductivity prediction values can be obtained. The transposed and parallel arrangement effects on litz wire equivalent thermal conductivity are compared and discussed. This study shows that the transposition arrangement could improve litz wire heat dissipation capability by 10% to 30%, demonstrating that electrical machine power density can be potentially increased by up to 14%. The proposed method can advance winding design to push the boundaries of electrical machine power density.

中文翻译：

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包含换位效应的利兹线成形绕线绕组的等效热导率预测

力兹线已广泛用于高频电机和变压器中，以最大程度地减少感应电流损失并保持高效率。它的散热能力可能是高功率密度高频电机的关键设计因素。尽管已经研究了绞合线等效热导率，但通常忽略了其在增强散热方面的换位安排。本文着重于开发一种分析模型来预测利兹线等效热导率，包括换位效应。使用3-D有限元模型和硬件实验来验证所提出的分析模型。可以获得快速准确的绞合线热导率预测值。比较并讨论了转置和平行排列对绞合线等效导热系数的影响。这项研究表明，换位布置可以将绞合线的散热能力提高10％到30％，这表明电机的功率密度可以潜在地提高14％。所提出的方法可以推进绕组设计以突破电机功率密度的边界。