Electric machine for aircraft propulsion is required to have high power density and high reliability, but the harsh operating environment, such as low air pressure, will challenge the motor’s insulation system. This article presents the partial discharge (PD) investigation of the form-wound winding in high-frequency electric machines for electric aircraft propulsion. Experimental results show that the PD activity is largely enhanced due to the decrease in air pressure. PD inception voltage (PDIV) decreases to ~50%–60%, and the PD magnitude dramatically increases when the pressure drops from 1 to 0.2 atm. Several windings with introduced defects were also tested to extract features from phase-resolved PD (PRPD) analysis, which can be used for PD pattern recognition. In addition, a PD-based failure precursor, combining the apparent charge, number, and phase interval of the monitored PD profile, is proposed to monitor the insulating condition of the thermally and electrically aged windings. The proposed failure precursor generally shows a rising trend with the aging time in this article. The application of the proposed failure precursor on online condition monitoring needs more investigation through long-term online observation of the electric machine.

中文翻译：

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电动飞机推进用绕线电机绕组的局部放电研究

飞机推进电机要求具有高功率密度和高可靠性，但恶劣的运行环境，如低气压，将对电机的绝缘系统提出挑战。本文介绍了用于电动飞机推进的高频电机中成型绕组的局部放电 (PD) 研究。实验结果表明，由于气压的降低，PD活性大大增强。PD 起始电压 (PDIV) 降低至~50%–60%，并且当压力从 1 atm 降至 0.2 atm 时，PD 幅度急剧增加。还测试了几个引入缺陷的绕组，以从相位分辨局部放电 (PRPD) 分析中提取特征，可用于局部放电模式识别。此外，基于 PD 的故障前兆，结合了表观电荷、数量、被监测的 PD 曲线的相位间隔和相位间隔被提议用于监测热老化和电气老化绕组的绝缘状况。本文提出的失效前兆一般随着老化时间的增加呈上升趋势。所提出的故障前兆在在线状态监测中的应用需要通过对电机的长期在线观察进行更多的调查。