基于双向预充控制的RSD低能耗重频触发特性研究

In recent years, research and development on practical industrial applications of repetitive pulsers have focused on solid state pulsed power generator using semiconductor and magnetic switches. Evolution of switching technology has greatly changed the concept of pulsed power and its applications. For most solid-state pulsed power generators, the output power level, the repetition rate, and the lifetime are determined by the capability of the semiconductor switches. With properties of high frequency, high efficiency, high power density and high reliability, solid-state pulsed power semiconductors and magnetic switches are preferred candidates for controlling switch applied in the pulsed power devices to replace conventional gas-discharge switches, for example, hydrogen thyratron or spark gap. As a new high-power semiconductor component capable of switching gegawatts level high power, Reserve Switching Dynistor(RSD) is a preferred candidate for the conventional switches. However, some severe restriction impacts the practical applications of RSD-based puled power generator, for example, high controlling energy losses in RSDs connected in series, nonsynchronous switching and design of the complete switch assemblies modular. The reliability of a high-voltage RSD operation is primarily determined by the reliability of the trigger circuit. Relationship between trigger circuit parameters and RSD trigger charge carrier value will be built in order to develop a high power generator based on multi-chip serial RSD. Two-phase switching method for triggering RSD is presented. Judging from switching process uniformly and stably, the critical value of the injected charge could be used to guide the parameter design of parallel resonance trigger circuit in order to ensure the uniform switching of an RSD. The trigger circuit design will be verified by a single module triggering experiment, which are helpful for the development of high voltage RSD multi-chip series trigger circuit and implementation of microsecond width fast pulse current output. The basic principles of a new two-phase controlling method for a uniform switching-on over the whole wafer will be analyzed to significantly reduce the amplitude and duration of necessary triggering current. The distributed structure based parallel-resonant triggering circuit will be proposed. Low triggering energy loss and high controlling reliability in this two-phase triggering method will be considered through a thin base region width and low blocked voltage dynistor. It is necessary to reduce the using of magnetic switch core material for a low energy losses. So, a short pulse is required for magnetic pulse compression nets(MPC). Basic design of the modular pulsed power switch unit will be proposed, which has distinct advantage of flexible output high voltage extension to meet increased reliability, lower maintenance, and availability needs.

用半导体开关替换传统的气体间隙开关，提高脉冲电源作用能效、重复频率和功率密度是固态脉冲领域的研究热点。目前制约脉冲功率技术产业化的瓶颈是能够以高效率长期稳定运行的长寿命、大功率重频脉冲电源的研制，关键是具备足够通流容量、速度和控制可靠性的功率开关组件的研究。作为一种新型器件，RSD比其他半导体开关具有更强的通流能力，是传统开关最有前途的替代品。但制约高压串联RSD实际应用的高触发能耗、控制稳定性及组件化结构等方面的问题亟待解决。本项目针对用于磁压缩网络重频充电的高压RSD强触发技术，研究新型双向预充模式下器件均匀导通的临界触发判据；在提高器件的控制可靠性的同时，降低高重复频率工况下RSD的触发能耗。针对薄基区低压RSD提出双向预充电路及其分布式触发结构，完善RSD组件化高压拓展功能。确保RSD导通电流快速为磁压缩环节充电，提高系统整体效率和功率密度，推动固态重频脉冲源实用化技术的发展。

目前，固态脉冲功率技术正处在一个飞速发展阶段，即重复频率应用阶段。固态重频脉冲电源的发展，在很大的程度上依赖于开关技术的突破。现下，该领域最具有应用前景的开关是反向触发双晶复合晶体管RSD，单晶片可以承受几千伏高电压、流通上百千安培大电流、并且实现微秒/纳秒级内的高速开通。目前由高压RSDs组件构成的高重复频率固态脉冲源还未实现工业化应用推广。究其原因，一是由于传统触发模式带来的高触发能耗阻碍了其在重频脉冲源当中的应用；二是因为RSD特殊的触发控制方式，缺少专用的组件化结构设计，其在不同耐压、容量需求下缺少可拓展性和灵活性。.本项目的研究内容侧重于一种低能耗的触发技术，相比于传统触发方式能够增强RSD的饱和导通程度，降低换流损耗，使其更适用于重频放电系统。项目在以下几个方面完成了探索：1. 研究了RSD独特的内部机理，阐述了其可靠导通所需条件，即在预充阶段通过形成分布均匀的等离子层，积累足够的电荷——临界预充电荷。2. 针对常规触发的不足，提出一种正反双向触发电路，完成新型触发电路参数设计优化。本质上通过增加的正向电荷预充阶段，降低其触发过程中的导通压降尖峰，从而减少换流损耗。3. 对高压RSDs堆体结构进行设计，建立完整的充、放电系统。在快脉冲放电对结构紧凑性高要求的前提下，为使放电系统对高电压拓展具有灵活性，对单元RSD及其触发电路采取可级联模块化设计。最后，基于RSD固态脉冲源平台开展三模块级联低重频放电实验，开通电压1.8kV放电电流上升率1.2kA/μs；重复频率7s/次。实验数据表明：双向触发电路将换流过程中RSD的电压尖峰限制在20V以下，明显低于单步触发情况。获得结论：双向触发技术的反向预充阶段降低了电荷量的存储需求；其正向预充阶段对载流子的浓度起到了维持的作用、防止了载流子的耗尽，有效地降低了换流电压尖峰与换流损耗，得到了正反双向触发方式可降低换流损耗的依据。