EAST中性束注入用直流高压缓冲器磁滞模型分析

Analysis on the Hysteresis Model of Core Snubber for EAST Neutral Beam Injector

直流高压缓冲器是国家大科学工程先进实验超导托卡马克(EAST)中性束注入(NBI)系统中保护强流离子源的重要装置。为设计高可靠性的直流高压缓冲器,在Fink、Baker和Owen(简称F-B-O)直流高压缓冲器采用时变等效电阻而忽略并联电感的模型基础上,结合平行四边形磁滞模型,建立了时变等效电阻和电感并联的模型,推导出时变等效电感随饱和深度的解析式,并建立了相应的仿真模型。仿真结果与实测结果基本符合,修正后的模型在30kV以下低电压作用下与F-B-O原模型符合,在30～80kV电压作用下,随着铁芯叠片饱和深度逐渐升高,时变等效电感作用引起的故障电流比理论计算值高10%～30%。

Core snubber is one of the most important devices in experimental advanced superconducting tokamak （EAST） neutral beam injector（NBI） syetem, which is designed to protect the neutral beam injector system during the period of high voltage breakdown. The theory for core snubber was developed by Fink, Baker and Owen（F-B-O） model which considered only the snubber resistance effects and ignored the effect of inductance condition. We proposed an approach to limit the high voltage breakdown effects by the concepts of the equivalent resistance and inductance in parallel mode implemented with Deltamax cores. Thereafter, a series of related formulas were deduced and the circuit fault simulation code was primarily established which could simulate fault conditions with above time- varying resistance and inductance. This snubber was tested at voltage below 100 kV with 4 nF discharge capacitor. The results show that the fault peak current is higher than that by the original F-B-O model between 30 kV to 80 kV of the test conditions. High voltage fault current is 10% - 30% higher than the theoretical value. The simulation code is calibrated with the test results.