Validity of constant voltage stress based reliability assessment of high-/spl kappa/ devices

Charge trapping in high-/spl kappa/ gate dielectrics affects the result of electrical characterization significantly. DC mobility degradation and device threshold voltage instability and C-V and I-V hysteresis are a few examples. The charging effects in high-/spl kappa/ gate dielectric also affect the validity of conventional reliability test methodologies developed for SiO/sub 2/ devices. In this paper, we review high-/spl kappa/ materials specific phenomena that can affect the validity of constant-voltage-stress-based reliability test methods to address the direction of future reliability study on high-/spl kappa/ devices.     

Analysis of the voltage phasors characteristics for motor unbalanced supplies under constant voltage level

This article presents an analytical and graphical study of the supply characteristics of a three-phase induction motor operating under constant average voltage in unbalanced conditions. Till now, researchers have addressed the unbalance analysis of induction motors without paying attention to the accuracy on the voltage level issue. This work develops the loci of voltage phasors and their symmetrical components, and calculates the variation ranges of voltages and voltage unbalance factor (IEC) for an induction motor operating under constant line average voltage and constant percent voltage unbalance (NEMA). The results are applied to the variation limits established in the electrotechnical standards.     

静电除尘器用恒压源与恒流源中试试验研究

高压电源是静电除尘器的核心部件,本文通过在芒刺线单室湿式静电除尘器试验平台下开展中试试验,采用静电低压撞击器（ELPI）实时在线测量不同粒径颗粒物的荷电量及其浓度分布,对比研究了当前静电除尘器使用的单相恒压源和单相恒流源2种供电形式的除尘效率、颗粒物荷电特性、伏安特性、功耗等试验指标。试验结果表明:在不发生过量的火花击穿前提下恒压源相比于恒流源具有更高的平均运行电压和更高的电晕电流,恒压源和恒流源最高平均电压分别为70 kV和55 kV,电晕电流分别为7.12 mA和6.00 mA,所对应的最大除尘效率分别为85.9%和84.2%;在相同除尘效率下恒压源相比于恒流源节能20%,因此恒压源比恒流源更具有技术和经济优势。相关结论对静电除尘器改造升级具有一定的参考价值。     

Electron trap generation in high-/spl kappa/ gate stacks by constant voltage stress

Positive bias constant voltage stress combined with charge pumping (CP) measurements were applied to study trap generation phenomena in SiO/sub 2//HfO/sub 2//TiN stacks. Using gate stacks with varying thicknesses of the interfacial SiO/sub 2/ layer (IL) or high-/spl kappa/ layer and analysis for frequency-dependent CP data developed to address trap depth profiling, the authors have determined that the defect generation in the stress voltage range of practical importance occurs primarily within the IL on as-grown "precursor" defects most likely caused by the overlaying HfO/sub 2/ layer. The generated traps can be passivated by a forming gas or nitrogen (N/sub 2/) anneal, whereas a postanneal stress reactivates these defects. The results obtained identify the IL as one of the major targets for reliability improvement of high-/spl kappa/ stacks.     

锂离子蓄电池恒压补充电方法研究

针对锂离子蓄电池健康充电目标,探索了一种锂离子蓄电池恒压补充电方法。该方法结合锂离子蓄电池充电管理过程,基于反馈控制思想,实现了锂离子蓄电池的恒压补充电。该方法在研制的机载蓄电池地面维护设备中探索应用,应用于锂离子蓄电池的充电维护、循环充放电活化过程。实验结果表明,该方法在充电过程中,能够较好地实现恒压补充电,充电速率较原有限压补充电方式提高20%。在补充电时,锂离子蓄电池温度保持在合适范围内,充电效率和充电时间等参数得到有效提高。该方法对锂离子蓄电池使用寿命的延长有一定促进作用。     

Resonant circuit with constant voltage applied on the clamp capacitor for zero voltage switching of power converters

Contents This paper presents a new resonant circuit meant to switch the solid state devices by ZVS at the power converters. It only acts before these switchings and has the clamp capacitor supplied of constant voltage. This resonant circuit is characterized by a low clamping ratioK (between 1.15 and 1.20) and a small total duration of its operation. Finally, certain application possibilities of the proposed circuit are presented.

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Ein Resonanzkreis mit konstanter Spannung am Clampkondensator zum Schalten von Umrichtern bei Nullspannung

Übersicht In der Arbeit wird ein neuer Resonanzkreis für die Ausführung von Schaltungen der Halbleiterbauelemente von Umrichtern für ZVS beschrieben. Er wird nur vor den Umschaltungen betrieben und besitzt einen Clampkondensator mit konstanter Speisespannung. Dieser Resonanzkreis zeichnet sich durch einen wertmässig reduzierten Clampfaktor (zwischen 1,15 und 1,20) und eine kleinere Gesamtarbeitsdauer aus. Zum Schluß werden einige mögliche Anwendungen des vorgeschlagenen Schaltkreises vorgestellt.

     

A new variable speed constant voltage controller for self-excited induction generator

A new variable speed, constant voltage controller for self-excited induction generator (SEIG) is presented in this paper. The proposed PWM controller regulates the induction generator (IG) terminal voltage against varying rotor speed and changing load conditions. This scheme does not require any real time computations and information regarding rotor speed for calculating the excitation current, thereby minimizing the electronic hardware and the cost of the controller. A simple, over-current protection is incorporated to protect the inverter switches. Computer simulation and experimental results show satisfactory operation of an induction generator with the proposed control scheme.     

聚合物锂离子蓄电池恒压充电时间过长的机理

宝龙工业有限公司在聚合物锂离子蓄电池生产过程中出现恒压充电时间过长 ,并且随充放电循环次数的增多 ,变得越来越长的问题 ,通过实验对这一现象做了初步的探讨。发现 :在该种电池的电解液中不同价态钴离子的溶解量远远高于正常电池 ,并使电池内部电极和电解液呈红色。分析Co2 + 和Co3 + 的d轨道电子分布状况 ,得知它们d轨道中的一个电子可以互相转移 ,所以这种电池内部的电解液存在电子导电 ,在充电过程中出现漏电。这一结论为顺利解决电池恒压充电时间过长的技术问题提供了理论依据。     

Constant frequency and constant voltage control of induction generator

A doubly fed induction generator is useful for a local-use water power plant. Setting it in nonconstant water flow, we can use it as a constant-frequency power generator. This paper shows how to control this generator system. This paper has two important points. One is that this generator system is always excited at primary winding. Another is that the control target in this study is secondary q axis current to obtain a constant voltage of primary generated power.     

适用于抑制电压闪变的储能技术比较

大部分用于改善和提高电能质量的补偿装置都具有抑制电压闪变的功能,但都有一定的局限性.储能技术可以弥补各种补偿装置的局限性,抑制过低电压造成的闪变。通过对各种储能技术的分析,得出飞轮储能及超级电容器是最适合用于抑制电压闪变的储能技术。     

Characteristics of a self-excited induction generator at constant voltage and constant frequency under speed change

A self-excited wound-type induction generator, excited by capacitor, which changes its speed as a wind generator and can be used as a separate small power source, is described. The voltage and frequency of this generator change in accordance with the capacitance C of capacitor, generator speed and loads, and the like. The constant-voltage generator with constant C is achieved by returning the secondary power of the induction generator to the primary source through a converter, an inverter, and a transformer, and controlling the inverter control angle. But the frequency changes slightly. In order to eliminate frequency variation under constant C, a constant-frequency source such as synchronous generator or a constant-frequency generator is connected to the primary or secondary side of the transformer and operated in parallel. Constant voltage and constant frequency are achieved in spite of the change of generator speed and load. The characteristics resulting from these various measures are compared. The constant-frequency generator is better than the synchronous generator in terms of life, maintenance, and the like. In parallel operation with the constant-frequency generator connected to the primary or the secondary side of the transformer, various characteristics at constant voltage and commercial frequency are compared and analyzed. © 1997 Scripta Technica, Inc. Electr Eng Jpn 119(1): 90–100, 1997     

宽幅压输入、恒压输出的ZVZCT-PWM SEPIC变换器分析设计

分析ZVZCT-PWM SEPIC拓扑结构的工作原理,一个开关周期内得到14种工作模态.在宽幅压输入、恒压输出,以及SEPIC变换器工作于电流连续模式(CCM)的条件下,对其各元件参数进行了优化选取,并计算出辅助开关管在主开关管占空比变化后相应的具体导通、关断时间.Matlab软件仿真结果表明,该变换器在上述条件下能够...     

锌-氧化银电池恒压充电的性能研究

探讨了采用锌 氧化银电池做UPS电源 ,在恒压充电电压与放电电压极其接近的情况下 ,能否保证足够的充电效率 ,能否提供足够的充电容量。并对充电电流的变化做了一些粗略的分析 ,计算出恒压充电的容量 ,将其与正常的恒流充电比较 ,解决了某工程用锌 氧化银电池设计过程中的一些关键问题。     

压控恒流源的动态性能研究

研究了一种常用的恒流源电路的输出动态特性。研究发现：在负载及输出电流值不变的情况下,影响恒流源动态性能的主要因素是误差放大器积分电容的容值、反馈放大器的放大倍数等;在电路参数固定的情况下,在一定的输出电流范围内,影响系统动态性能的主要因素是负载阻值,而电流值影响很小。最后,根据实际电路设计指标,提出了改善系统动态性能的解决方案,仿真及实际电路测试证明了结论的正确性。     

基于变结构补偿网络的WPT恒流/恒压充电系统

针对电动汽车充电无线电能传输(WPT)系统的网络补偿技术,研究了一种LCC-LCC/S型变结构补偿网络.通过开关控制,能够将松耦合变压器的原/副边补偿网络由恒流源-恒流源特性,切换为恒流源-恒压源特性,从而实现变化负载工况下的恒流或恒压输出,用以满足动力电池的充电需求.针对变结构切换过程中硬开关能量冲击导致的高电压应力...     

基于可调稳压芯片的数控恒流源

针对数控直流恒流源的设计进行了探讨,对比已有的恒流源实现方式,分析了其缺点,重点介绍1种高效率的基于可调稳压芯片的数控恒流源.给出了电路原理图,就整机工作原理、相关参数计算做了详细介绍.从系统组成角度分别介绍了核心模块、反馈模块及其实现方法.其基本原理是利用核心芯片的反馈引脚,把并联反馈改为串联反馈,从而实现恒流性能....