High-temperature superconductor (HTS) machine is a promising candidate for the electrical aircraft propulsion due to its great advantage in high power density. However, the HTS machine always suffers the problem of low thermal stability during quench. In this article, we apply a no-insulation (NI) coil technique on the rotor windings of HTS machines to enhance the stability and safety of the electrical aircraft. The NI HTS rotor windings experience ripple magnetic fields, which leads to induced eddy currents through turn-to-turn contacts. This induced current and accompanying losses will considerably affect the practicality of this technique. To study this issue, an equivalent circuit network model is developed, and it is validated by experiments. Then, analysis using this model shows that most of induced current flows in the outermost turns of the NI HTS coil because of skin effect, and lower turn-to-turn resistivity leads to higher transport current induced and more significant accumulation of turn-to-turn loss. A grading turn-to-turn resistivity is proposed to reduce the transport current induced and ac loss accumulation and meanwhile keep the high thermal stability of the NI HTS coil. Optimization of turn-to-turn resistivity is required when the NI HTS coil is applied in the machines’ environments.

中文翻译：

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电动飞机推进用无绝缘高温超导体绕制技术

高温超导体（HTS）机器由于其在高功率密度方面的巨大优势而成为电动飞机推进的有希望的候选者。然而，高温超导设备在淬火过程中始终存在热稳定性低的问题。在本文中，我们将无绝缘 (NI) 线圈技术应用于高温超导电机的转子绕组，以提高电动飞机的稳定性和安全性。NI HTS 转子绕组会经历波纹磁场，这会导致通过匝间接触产生感应涡流。这种感应电流和伴随的损耗将显着影响该技术的实用性。为了研究这个问题，开发了一个等效电路网络模型，并通过实验进行了验证。然后，使用该模型的分析表明，由于趋肤效应，大部分感应电流在 NI HTS 线圈的最外圈流动，较低的匝间电阻率导致更高的传输电流感应和更显着的匝间损耗累积. 提出了分级匝间电阻率，以减少传输电流感应和交流损耗累积，同时保持 NI HTS 线圈的高热稳定性。当 NI HTS 线圈应用于机器环境时，需要优化匝间电阻率。提出了分级匝间电阻率，以减少传输电流感应和交流损耗累积，同时保持 NI HTS 线圈的高热稳定性。当 NI HTS 线圈应用于机器环境时，需要优化匝间电阻率。提出了分级匝间电阻率，以减少传输电流感应和交流损耗累积，同时保持 NI HTS 线圈的高热稳定性。当 NI HTS 线圈应用于机器环境时，需要优化匝间电阻率。