【作者】 刘轩东；

【导师】 邱爱慈；

【作者基本信息】 西安交通大学 ， 电气工程， 2010， 博士

【摘要】 快脉冲直线变压器驱动源(Fast Linear Transformer Driver, FLTD)是一种新型的初级储能装置,采用多支路并联以获得大电流,通过多级串联感应电压叠加以获得高电压。其结构紧凑,采用模块化设计,串并联方便,不需要脉冲压缩和脉冲形成网络,直接驱动负载。在闪光照相、高功率微波、惯性约束聚变和惯性聚变能源中具有广阔的应用前景。作为FLTD的关键部件,气体开关的数目众多,其击穿特性直接影响FLTD的输出参数、稳定性和可靠性,目前,FLTD气体开关及其击穿特性研究已经成为脉冲功率技术领域的研究前沿和热点问题。因此,气体开关击穿特性及其对单模块FLTD、多模块串联FLTD影响的研究对FLTD技术的发展具有重要的科研研究意义和实际应用价值。本文首先搭建了开关击穿特性研究的实验平台,它基本上与FLTD模块单支路结构相同,包括开关、电容器、负载电阻、连接板等器件。研制了Rogowski线圈和电阻分压器,可用于开关击穿特性实验脉冲电流和电压的测量。研制了一种用于FLTD的六间隙气体开关,设计了小球支撑固定环状中间电极的结构,该开关在工作电压160kV、0.3MPa氮气下重复触发运行2000次无故障,平均击穿延迟时间为50.96ns,抖动为2.27ns。实验研究了六间隙气体开关的击穿特性。通过该六间隙气体开关自击穿电压的研究,得到了开关自击穿电压曲线,推导了不同工作电压和工作气压下六间隙气体开关的工作系数。提出了电感隔离的触发引入方法。电感隔离和电阻隔离方法的对比研究表明,电感隔离方式不仅有利于减小开关抖动,还能在开关出现自放电时,更有效地保护相邻开关和触发器。不同工作电压、气压、工作系数等条件下开关触发击穿特性的研究显示,用于FLTD时,六间隙气体开关工作系数应选择60%~65%以减小开关抖动和自放电概率,而修正常数项的马丁公式可用于估算六间隙开关击穿延迟时间。基于六间隙气体开关自击穿电压数据,根据三参数Weibull概率分布模型,分析计算了开关自放电概率。实验研究了六间隙气体开关2000次重复运行特性,提出并验证了六间隙气体开关击穿延迟时间近似呈正态分布。实验研究了FLTD模块的16只气体开关的自击穿电压、触发击穿延迟时间和抖动,掌握了开关平均击穿延迟时间的差异。通过分析40支路和14支路FLTD模块的触发引入结构和开关位置,提出了模拟FLTD模块中开关触发脉冲参数差异的方法。建立了14支路单模块FLTD,计算推导了模块的元件参数,建立了单模块FLTD的PSPICE电路仿真模型和MATLAB模拟计算模型,并利用短路负载下14支路FLTD模块的实验结果验证了两种模型仿真计算结果的正确性,研究结果表明,单模块FLTD中开关抖动较小时对输出脉冲前沿影响较为明显;开关抖动较大时,多次重复运行输出脉冲呈窄带状分布;开关自放电故障将引起模块电压波动,其趋势先减小后增大,振荡周期约580ns,幅值约10kV。分析了60级FLTD模块串联的工作原理,推导了其等效电路的元件参数,60级FLTD模块串联的模拟计算结果表明,随着开关数目增加,开关抖动对输出参数的影响减小。首端模块故障对串联系统影响较大,首端模块整体自放电或模块中单只开关自放电均可能导致后级模块陆续自放电,造成串联模块误动作。中间模块和末端模块若不能有效触发导通,在感应电压的作用下,可能稍迟于正常时序导通。更多还原

【Abstract】 Fast linear transformer driver (FLTD) is a developing technology for constructing high current high voltage pulse generator. The main feature of FLTD is inductively adding the relatively low voltage straight out of the capacitors. Its output pulse can be directly applied to the load without any pulse compressing and forming unit. Also, FLTD can be connected conveniently in series or parallel with different output parameters. Therefore, FLTD technology makes pulsed power devices more compact and less expensive to produce one hundred nanosecond pulse with high efficiency of energy transformation. It has wide application prospect in the fields of flash photography, high power microwave, excimer laser, Z-pinch and future inertial fusion energy, etc. As one of the critical elements, huge amounts of gas switches directly influence the output parameters, the stability and reliability of FLTD. In recent few years, gas switch and its breakdown characteristics are becoming focus and hot issues. As a result, the studies on the breakdown characteristics of multi gap gas switch and its influence on the single module FLTD and multi modules FLTD in series are important and urgent for the development of FLTD technology both in theory and application.In this dissertation, a gas switch with six gaps in series has been designed and improved for FLTD. A research platform was established for the breakdown characteristics of gas switch, which mainly included the basic discharging loop similar to a single brick of FLTD that consisted of six-gap gas switch, capacitors, load resistor and strip lines. Rogowski coil and resistance voltage divider were also developed for monitoring the pulse current and load voltage, respectively.The working ratio with different charge voltage and gas pressure were calculated according to the self breakdown voltage curve derived from the self break experiment data of six-gap gas switch. A new trigger access method with inductance isolation was proposed in this dissertation. The comparative experiment with both inductance isolation and resistance isolation indicates that the former method not only has benefit in reducing the switch jitter, but also effectively protects the adjacent switches and trigger generator if one of the switches in FLTD module prefires. The experimental results with different charge voltages, gas pressures and working ratios show that when it was used in FLTD, the working ratio of the six-gap gas switch should limited between 60%~65% to reduce the switch jitter and the prefire probability. The breakdown delay time can be calculated by using T.H. Martin formula with the constant term revised.By using three parameters Weibull probability distribution model, the prefire probability of six-gap gas switch was calculated according to the self breakdown data of three hundreds shots. A rule was proposed and proved based on the repetitive operation of six-gap gas switch with two thousands triggered breakdown shots, which indicates that the delay time distribution of the switch approximately obeys the normal probability distribution. The self breakdown voltages, triggered breakdown delay times and switch jitters of sixteen switches for FLTD module were studied. The difference of the average delay times of sixteen switches was also derived from the experiment results. The trigger access structure will cause trigger pulse of each switch different in the FLTD module. Therefore, equivalent switch jitter was put forward to simulate the difference of the trigger pulse parameters of each switch.A FLTD experimental system with fourteen bricks was established. Two models built by using PSPICE and MATLAB were proved by the experimental result of the FLTD system with short circuit load. The models were used to simulate the influence of switch jitter and faults on the output of FLTD module, respectively. The simulation indicates that switch jitter affects the pulse front more obviously than the pulse amplitude. The switch faults, however, has little effect in the single FLTD module.The principle of FLTD with sixty stages in series was analyzed. The parameters of equivalent circuit were derived and the model of sixty stages in series has been established. The simulated results indicate that the influence of switch jitter on the output pulse decreases when the FLTD system in series includes a large amount switches. Stage prefire as well as switch prefire in the first stage more likely cause prefires in the following stages. However, switch faults in the middle stages and end stage has little effect in the FLTD system. Even if the middle stages and end stage can not be triggered, they will breakdown slightly later than the normal trigger sequence because of the induced voltage.更多还原