瞬态电压抑制器的雷电通流与箝压特性测试

为提高箝位电压和峰值脉冲电流测量的准确度,利用冲击电流发生器测试3种系列不同类型瞬态电压抑制器的雷电流通流能力、箝位电压特性和伏安特性,分析了它们与额定电压、脉冲峰值功耗及极性的关系。结果表明,TVS额定电压越高,雷电流通流能力越小,同样额定电压的TVS管,脉冲峰值功耗增大后通流能力并未增大,TVS管只适宜作为次级限压性防护元件。随着额定电压的升高,箝位电压逐渐增大,临界箝位系数趋于减小,低额定电压时箝位电压分散性大,高额定电压时箝位电压分散性小,选用和考虑TVS绝缘配合时应予注意。     

A combined chemico-mineralogical and tensiometric approach for evaluation of Euganean Thermal Mud (ETM) quality

The tensiometric vs. skin approach (TVS modelling®) is a non-invasive method based on the permutability principle of tensiometry. TVS modelling® is a technologic model that can evaluate the reproducibility of the matrix of thermal mud, its degree of maturation and consequently its skin affinity, in a non-destructive way. This is an essential pre-condition for defining the objective scientific protocols. The surface energy profile of the matrixes is created by a Tenskinmeter®, a tensiometer modified by us for tensiometric measurements on skin. The development of a chemico-mineralogical index (I _chmi) based on X-ray fluorescence analysis allows the typical chemico-mineralogical constituents of thermal muds to be determined. The combined TVS-I _chmi approach developed here demonstrates the interconnections between the typical chemico-mineralogical components of a Euganean Thermal Mud (ETM) and its energy surface properties. The combined approach also demonstrates the interconnections at the interface between I _chmi and the skin affinity of the mud matrix, revealing their typical functional and therapeutic effects.     

基于TVS的电子设备ESD保护方法研究

针对静电放电(electrostatic discharge,ESD)脉冲电流对电子设备内部芯片造成破坏,本文采用瞬态二极管(transient voltage suppressor,TVS)作为ESD抑制器件,分析了TVS的防护机理,考虑到高频情况下寄生参数的存在,建立了ESD保护电路模型. 通过比较TVS抑制前后的负载两端的电压波形,研究其抑制性. 最后通过实验验证了TVS的防护效果.     

Parametric optimization and analysis of thermodynamic venting system in liquid hydrogen tank under microgravity

This paper used the lumped vapor model to simulate the self-pressurization and thermodynamic venting process in the cryogenic liquid hydrogen tank with 90% filling rate under microgravity. Based on the orthogonal experiment, twenty-five cases with different parameters were designed. Daily evaporation rate and cooling capacity utilization efficiency were proposed to evaluate the exhaust loss during the jet process and depressurization efficiency during depressurization process. The four parameters of spray bar including exhaust rate, diameter of inner tube of heat exchanger, nozzle length and number of nozzles were optimized and the weight of influence on the daily evaporation rate and cooling capacity utilization efficiency was analyzed. Results showed that nozzle length and number of nozzles played a key role in the daily evaporation rate and cooling capacity utilization efficiency, while diameter of inner tube of heat exchanger had little effect. Under the same mass flow, smaller nozzle length, lower exhaust rate and fewer nozzles could increase the inlet velocity, thereby reducing the daily evaporation rate and improving the cooling capacity utilization efficiency. The thermal stratification could be eliminated well. In addition, arranging two nozzles up and down was more advantageous than arranging a single nozzle in the middle. The research results were useful for improving the efficiency of the thermodynamic venting system (TVS) and extending the propellant storage time in orbit.     

鞍山市供水项目水厂自动化

本文结合自动化控制系统的实例,详细介绍了控制系统的配置和功能。该系统已经运行了一年多,节省了劳动力,提高了管理水平,产生了很好的经济效益。本文介绍了控制技术。TVS监控系统、监控仪表,德国西门子公司的产品。     

深槽TVS研究

以静电放电（ESD）以及其他一些电压浪涌形式随机出现的瞬态电压,通常存在于各种电子器件中。随着半导体器件日益趋向小型化、高密度和多功能。电子器件越来越容易受到电压浪涌的影响,甚至导致致命的伤害。从静电放电到闪电等各种电压浪涌都能诱导瞬态电流尖峰,瞬态电压抑制器（TVS）通常用来保护敏感电路受到浪涌的冲击。基于不同的应用。瞬态电压抑制器可以通过改变浪涌放电通路和自身的箝位电压来起到电路保护作用。为了节省芯片面积,并且获得更高的抗浪涌能力,深槽TVS的概念已经被提出和研究。深槽TVS的结面形成于纵向的深槽的侧壁,这样,在相同的芯片面积下,它有更多的有效结面积,即更强的放电能力。我们也可以预见,深槽TVS的小封装尺寸对应用于保护高端IC非常关键。     

小电流接地系统故障选线的一种新方法

小电流接地系统的故障选线一直备受供电部门关注。分析了中性点不接地系统单相接地故障及其选线存在的问题,并在此基础上提出了一种新的选线方案,即基于TVS的可控短路方案。利用MATLAB／Simulink进行仿真,结果表明该方法不仅能够弥补传统选线法的不足,而且具有一定的优势。     

半导体激光器电源防浪涌电路的设计

本文利用氧化锌压敏电阻、瞬态电压抑制器(TVS)以及慢启动电路设计了一款应用于半导体激光器的防浪涌保护电路,通过实际测量开关插拔瞬间电路的浪涌波形以及防浪涌保护的实际效果,测试结果证明该电路能够对该浪涌起到良好的防范作用,实现了对半导体激光器的防浪涌保护.     

瞬变电压抑制器失效模式和失效机理研究

由于目前对TVS自身可靠性的研究较少,提出了对TVS产品的可靠性研究.这项研究得到国内TVS生产厂家的支持,对该厂6个型号TVS筛选进行了跟踪.根据筛选失效数据,对温度循环、箝位冲击、高温反偏和功率老炼等TVS失效比例较大的筛选项目的失效品,经过电参数测试、解剖、显微观察,确定失效模式、分析失效机理.结果表明,TVS主要失效模式有短路、开路、反向漏电流大和异常击穿,且高击穿电压TVS更易发生失效.     

机载电子设备接口电路的雷电防护设计

随着对机载电子设备可靠性要求的提高,机载电子设备接口电路的雷电防护设计显得越来越重要.本文介绍了机载电子设备接口电路的雷电防护设计,分析了其雷电防护方法,给出了计算公式并指出了设计中需注意的问题.