基于PCB传输线和固态开关的高压纳秒脉冲发生器研制

发布时间：2018-08-19 18:42

【摘要】：近来,纳秒脉冲电场在生物医学等领域的应用潜力引起了国内外研究人员的极大兴趣。为研制紧凑型、便携式、轻量化高压纳秒脉冲发生器用于生物医学实验,本文结合PCB传输线和固态开关技术,研制了基于多种PCB传输线和固态开关的高压纳秒脉冲发生器。首先,本文介绍了基于PCB传输线和固态开关的高压纳秒脉冲发生器系统工作原理,通过对Blumlein传输线系统中电压波传播过程分析得出3种阻抗配合下系统输出方波脉冲的电压波传播过程以及相关调控策略;并采用Pspice仿真软件对多级传输线串、并联结构输出特性进行了细致分析,得到3种结构的多级传输线拓扑结构,能够适应生物细胞实验中对发生器输出脉宽变化以及不同阻抗负载的要求;此外,通过仿真软件分析了负载杂散电感、固态开关上升时间等因素对于系统输出特性的影响。然后,依据本文所设计纳秒脉冲发生器对于PCB传输线的要求,分别设计了3种形式的PCB传输线:平衡型Blumlein微带传输线、非平衡型Blumlein多层微带传输线、平衡型Blumlein多层带状线,并对这3种PCB传输线尺寸参数的计算过程进行了详细介绍;并以此为基础得出这些PCB传输线的分布电容值以便计算某一直流电源情况下系统重复工作频率。另外,介绍了固态开关参数选择及其驱动电路设计;为进一步提高固态开关耐受电压水平,引入门极“RCD”有源均压电路作为MOSFET串级电路的动/静态均压策略,以保证多级MOSFET串联情况下各个MOSFET单元之间的动/静态均压。最后,基于门极“RCD”有源均压策略制作了6级MOSFET串联模块作为基于平衡型Blumlein微带传输线、非平衡型Blumlein多层微带传输线、平衡型Blumlein多层带状线纳秒脉冲发生器的开关,并通过实验验证其输出特性。此外,依据系统紧凑型要求,选择面积更小、沿面闪络电压更高以及屏蔽效果更好的带状线作为层叠单元,分别将带状线并联、串联以及混合连接以获取合适的输出阻抗及方波脉宽,最后分别对采用3种连接方式的层叠带状线纳秒脉冲发生器进行了相关测试。其中,重点对4级带状线串联型高压纳秒脉冲发生器进行了实验测试,实验结果表明,该发生器输出脉冲幅值0~3 k V连续可调、脉宽(几十ns~数百ns)可扩展、重复工作频率(0~几k Hz)可调且输出方波脉冲上升约20 ns左右的方波纳秒脉冲,有益于生物医学实验中对于系统输出方波脉冲宽度变化且系统紧凑、便携、重量轻的要求,为研究纳秒脉冲电场的生物医学效应奠定了基础。
[Abstract]:Recently, the application potential of nanosecond pulsed electric field in biomedicine and other fields has aroused great interest of researchers at home and abroad. In order to develop compact, portable, lightweight high-voltage nanosecond pulse generator for biomedical experiments, a high-voltage nanosecond pulse generator based on a variety of PCB transmission lines and solid-state switches is developed in this paper, based on PCB transmission line and solid-state switch technology. Firstly, this paper introduces the principle of high voltage nanosecond pulse generator based on PCB transmission line and solid state switch. By analyzing the propagation process of voltage wave in Blumlein transmission line system, the voltage wave propagation process of output square wave pulse of the system with three kinds of impedance matching and related control strategies are obtained, and the multistage transmission line string is simulated by Pspice software. The output characteristics of the parallel structure are analyzed in detail, and three kinds of multistage transmission line topologies are obtained, which can adapt to the variation of the output pulse width of the generator and the different impedance loads in the biological cell experiment. The influence of the load stray inductance and the rise time of the solid state switch on the output characteristics of the system is analyzed by the simulation software. Then, according to the PCB transmission line requirements of the nanosecond pulse generator designed in this paper, three kinds of PCB transmission lines are designed: balanced Blumlein microstrip transmission line, non-equilibrium Blumlein multilayer microstrip transmission line, balanced Blumlein multilayer strip line. The calculation process of the dimension parameters of the three kinds of PCB transmission lines is introduced in detail, and the distributed capacitance values of these PCB transmission lines are obtained on the basis of this, in order to calculate the system repetition frequency in the case of a certain constant current power supply. In addition, the parameter selection of solid-state switch and the design of driving circuit are introduced. In order to further improve the voltage tolerance level of solid-state switch, the gate "RCD" active voltage sharing circuit is introduced as the dynamic / static voltage sharing strategy of MOSFET cascade circuit. In order to ensure the dynamic / static voltage sharing between the MOSFET units in multistage MOSFET series. Finally, based on the gate "RCD" active voltage sharing strategy, a 6-stage MOSFET series module is fabricated as a switch based on balanced Blumlein microstrip transmission line, non-equilibrium Blumlein multi-layer microstrip transmission line and balanced Blumlein multilayer band line nanosecond pulse generator. The output characteristics are verified by experiments. In addition, according to the system compact type requirements, the strip lines with smaller area, higher flashover voltage along the surface and better shielding effect are selected as stacked units, respectively, and the strip lines are connected in parallel. In order to obtain the appropriate output impedance and square pulse width in series and hybrid connection, the correlating tests of three kinds of cascaded band line nanosecond pulse generator are carried out. The experimental results show that the output pulse amplitude of the generator is 0 ~ 3 kV continuously adjustable, and the pulse width (tens of ns ~ hundreds ns) can be extended, especially for the 4-stage strip line series high-voltage nanosecond pulse generator, and the experimental results show that the output pulse amplitude of the generator can be adjusted continuously and the pulse width (tens of ns ~ hundreds of ns) can be extended. The square wave nanosecond pulse whose repetition frequency (0 ~ several k Hz) is adjustable and the output square wave pulse rises about 20 ns is beneficial to the requirements of the system in biomedical experiments for the variation of the width of the output square wave and the compact, portable and light weight of the system. It lays a foundation for studying biomedical effect of nanosecond pulsed electric field.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN41;TN782

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