脉冲磁体绝缘破坏机理及诊断技术研究

For the moment, the pulsed field technology is the only way to obtain the magnetic field of higher than 50T, but the life time of pulsed magnets is limited by the damage of insulation. Because the traditional insulation breaking theory of pulsed magnets dosen't take transient effect of voltage and temperature field as well as the interaction force between windings into account and the fault detection technique can't local the fault position for the breaking mechanism sovling,this project will propose a new detection coil matrix which can local the fault positon along with the Fiber Bragg Grating Sensor to investigate both the electromagnetic and stress aspects of the magnets. Moreover, all the impacts to the magnet insulation driven by the transiet voltage, thermal shock and time-varying lorentz force will be studied through experiments in this project. Specifically speaking, those effects include uneven distribution of voltage, high temperature changing rate, large temperature gradient, squeezing or cutting between windings caused by loreznt force. This project is expected to achieve two targets: to promote the investigation development of the insulation breaking mechanism to a new level and to present a valid fault detecting technique and a diagnosing thoery to predict the breaking of magnets for the application and development of pulsed magnet technology.

目前脉冲强磁场技术是获得50T以上非破坏性强磁场的唯一有效手段，但是脉冲磁体的使用寿命受到绝缘破坏的严重制约。针对当前脉冲磁体绝缘破坏理论中没考虑到电压、温度场等的时变效应的影响,也没有全面研究电磁力所造成的绕组相互作用对绝缘的危害等理论盲点，以及针对目前绝缘故障探测技术存在的可靠性差、不能定位故障点等缺点，本课题从研究瞬变电压、热冲击和电磁力场等的分布或变化规律对绝缘破坏影响的角度出发，设计多种脉冲放电实验来模拟磁体实际工作状态，采用本课题首次提出的抗干扰能力强并能定位故障的探测线圈阵列方案，结合现有的光纤光栅传感器技术，分别对磁体进行电磁和力学两个方面的探测，研究绕组中电压分布不均、大温度梯度和大温度变化率以及绕组内作用力对绝缘破坏的影响。期望通过这些研究获得脉冲磁体绝缘破坏理论上的新突破，建立一套有效的脉冲磁体绝缘破坏探测诊断理论，预测磁体破坏，避免损失，并可指导磁体技术水平的提升。

脉冲强磁场技术是获得50T 以上强磁场的唯一有效手段，但是脉冲磁体的使用寿命受到绝缘破坏的严重制约。通过研究本项目成功解决了脉冲磁体绝缘破坏时微弱局放信号的探测技术，将局放信号探测灵敏度提高几个量级，为脉冲磁体绝缘破坏监测与破坏机理研究奠定了坚实基础。通过实验还验证了本项目提出的探测线圈阵列定位绝缘故障技术切实有效可行。将局放探测实验结果与脉冲磁体实际工作情况及传统理论结合，详细分析了脉冲磁体绝缘破坏时，局放信号的特点及其发生机理，进一步揭示了脉冲磁体绝缘破坏机理。通过研究压力对局放信号的影响发现电磁力不会影响局放信号，但是电磁是引起绝缘损伤、破坏的主要原因。层间电压高，而且电磁力对换层影响又大，换层处是脉冲磁体绝缘最薄弱处，需加强绝缘。本项目研究完满完成预期目标。