电工技术学报2024，Vol.39Issue(9)：2887-2895,9.DOI:10.19595/j.cnki.1000-6753.tces.230280
中频真空电弧边缘击穿现象及仿真研究
Experiment and Simulation for Edge Breakdown in Intermediate Frequency Vacuum Arc
摘要
Abstract
The C919 aircraft is a typical more-electric aircraft equipped with an aviation variable frequency AC power system(intermediate frequency 360～800 Hz),which is also the latest development direction of power supply technology for large aircraft.In the process of localization of core components of more-electric aircraft,the current technical bottleneck is the extinguishing of intermediate frequency and high current arc of small volume aviation electrical apparatus.The application of vacuum switch is expected to solve the problem of arc extinguishing at intermediate frequency.At present,the main research methods of intermedia frequency vacuum arc include experimental observation and modeling simulation,among which modeling is an effective method to reveal the physical nature of arc discharge process. Firstly,in order to facilitate the acquisition of arc images,a short circuit experiment was carried out in the vacuum arc chamber with the shield removed.The experiment spacing was 3 mm,the diameter of the contact was 41 mm and 20 mm,and the gas pressure in the arc extinguishing chamber was 5×10-4 Pa.Short-circuit current forming intermediate frequency vacuum arc was generated by energy storage capacitor and inductor,with adjustable frequency of 360～800 Hz and maximum peak value of 20 kA.The intermediate frequency vacuum arc generating circuit consists of two branches:oscillation and arc initiation. Secondly,the dual-temperature magneto hydro-dynamic(MHD)model of intermediate frequency vacuum arc was established,which is based on the following assumptions:(1)The arc column region was completely ion-ized,containing only ions and electrons,without the effect of neutral particles.(2)The order of magnitude for Debye length was 10-8 m,and the order of magnitude for electron mean free path was 10-4 m,and the gap of contact was 3 mm.Thus,the region was quasi neutral,and the intermediate frequency vacuum arc can be equaled to MHD fluid.(3)the order of magnitude average collision time for electron and ion was 10-11 s and 10-9 s respectively.The order of magnitude of travel time for electron and ion was of 10-7 s and 10-6 s respectively.The half wave time of IF vacuum arc was 0.62～1.38 ms,thus,the solving process can be considered a steady state problem.(4)The electron was an ideal gas,so the mass flow,inertial component and viscous component are all ignored.(5)The intermediate frequency vacuum arc plasma was not in local thermodynamic equilibrium state,so the ion temperature and electron temperature need to be calculated separately.(6)The arc column region was taken as supersonic fluid,and both the anode sheath and cathode spots are taken as the boundary. The following conclusions can be drawn from the experiment and simulation analysis:(1)According to the experiment,the edge breakdown phenomenon of the intermediate frequency vacuum arc is found,and serious ablation is observed at the edge of the contact of the vacuum arc chamber,which reflected the local weak point in the insulation strength at the post-arc stage.(2)According to the simulation results of dual-temperature MHD model,the maximum ion number density of intermediate frequency vacuum arc is 2.6×1019 m-3,and the ion temperature range is 0.30～0.91 eV,and the electron temperature range is 1.50～2.43 eV.The above data is consistent with the order of magnitude of vacuum arc microscopic parameters obtained by other scholars,indicating that the calculation results of the model in this paper are correct.(3)According to the simulation results,the reason for the increase of electron temperature is Joule heat.Because of the energy exchange between electrons and ions,the change of electron temperature will cause the change of ion temperature.The highest ion temperature is found at the edge of the anode contact,which coincided with the experimental edge breakdown position,indicating that energy concentration exists here.(4)According to the simulation results,the intermediate frequency vacuum arc is supersonic flow,the velocity changes little in the arc column area,and the velocity slows down at the boundary.According to the fluid energy conversion theory,the heat energy in low-speed region is high,which indicates that the mass flow of the intermediate frequency vacuum arc plasma is the essential cause of the edge breakdown.关键词
航空变频电源/中频真空电弧/弧后击穿/边缘击穿/双温磁流体动力学模型Key words
Aviation variable frequency power supply/intermediate frequency vacuum arc/post-arc breakdown/edge breakdown/two-temperature magneto hydro-dynamic model分类
信息技术与安全科学引用本文复制引用
蒋原,马速良,武建文,李擎,朱立颖..中频真空电弧边缘击穿现象及仿真研究[J].电工技术学报,2024,39(9):2887-2895,9.基金项目
国家自然科学基金面上项目(52177127)、广东省基础与应用基础研究基金项目(2020A1515110725)和航空科学基金项目(2020Z025074001)资助. （52177127）
