大型LTD装置功率源可靠性初步分析

Reliability of large LTD device analysis

产生脉冲电流约50 MA的大型LTD装置功率源由数十万个电容器、开关和触发器组成。规模庞大的功率源采用串联系统可靠性模型,其可靠度想要达到一个较高的水平,存在所要求的开关可靠度难以实现的情况。大型LTD装置功率源的主要故障模式为开关自击穿和触发器故障,开关自击穿将导致其所在的模块故障,而触发器一对多的触发方式,使其故障时引起更多的模块故障。在LTD装置输出性能满足要求的前提下,允许存在一定数量的模块故障,并且控制故障模块分布,是实现功率源高可靠度的关键。基于概念设计的大型LTD装置功率源构成框架,分别建立了在功率源、支路、分层上控制故障模块数量的可靠性模型。采用蒙特卡罗方法对该模型进行仿真计算,得出了在给定的功率源可靠度条件下开关和触发器需要达到的可靠度。为实现该可靠性模型,使故障模块不对其他部分产生影响,还对故障模块隔离技术进行了分析。

A large LTD device capable of delivering about 50 MA pulsed current to load consists of hundreds of thousands of capacitors,switches and trigger units.To achieve high reliability of such an enormous system is quite difficult with the series system reliability model,the required reliability of each switch is almost impossible to realize.The main fault modes of LTD device are switch prefire and trigger unit fault.The switch prefire will result in the failure of the LTD cavity where the prefire occurs.The fault of trigger unit would affect more LTD cavities because one trigger unit triggers several LTD cavities.The key to achieve high reliability level and meet the required performance,it is key that some fault LTD cavities are allowed and the number of fault LTD cavities is limited in different place.In this paper a reliability model of the LTD system is built from a conceptual design of the LTD device.The number of the fault LTD cavities would be strictly limited in the system,module and layer in the reliability model.For a given system reliability,the reliability values of switch and trigger unit are calculated by Monte-Carlo method.The method of fault isolation is also analyzed.