充中性气体RBWO中等离子体引起的脉冲缩短现象研究

针对严重制约强流加速器能量向高功率微波高效转化的脉冲缩短现象,设计了一种吉瓦级、紧凑型、同轴引出电子束相对论返波振荡器(RBWO),利用KARAT 2.5维全电磁粒子模拟程序研究了器件内部充中性气体时,碰撞电离所产生的等离子体对输出微波性能的影响,探讨了导致脉冲缩短的机制.模拟结果表明:充入一定浓度中性气体时,碰撞电离产生的等离子体在电子束传输的路径上形成离子通道,有效中和电子束径向空间电荷力,有利于电子束的传输及束-波作用,但必须控制在一定密度范围内,否则会引起输出微波脉冲缩短;等离子体密度随着充填中性气体密度的增加而增加,且与中性气体的核电荷数相关,等浓度时核电荷数大的气体更易导致输出微波脉冲缩短.     

LiFePO4正极材料改性研究进展

LiFePO4正极材料具有价格低廉、电化学循环稳定性及热稳定性好的优点,但由于自身的电子电导率、离子传导率较差,限制了其在大功率电池领域的应用。论述了近年来为增大LiFePO4材料的倍率性能而做的改性研究,从表面包覆、锂位掺杂、铁位掺杂、阴离子位掺杂等方面对国内外的发展动态进行了总结。     

All-Fiber Low-Noise High-Power Femtosecond Yb-Fiber Amplifier System Seeded by an All-Normal Dispersion Fiber Oscillator

We report an all-fiber, high-power, low-noise amplifier system seeded by an all-normal-dispersion-mode-locked Yb-doped fiber laser oscillator. Up to 10.6 W of average power is obtained at a repetition rate of 43 MHz with diffraction-limited beam quality. Amplified pulses are dechirped to sub-160-fs duration in a grating compressor. It is to our knowledge the first high-power source of femtosecond pulses with completely fiber-integrated amplification comprising commercially available components. Long-term stability is excellent. Short-term stability is characterized and an integrated laser intensity noise of $≪$0.2% is reported. We also conclude that all-normal dispersion fiber oscillators are low-noise sources, suitable as seed for fiber amplifiers. Detailed numerical modeling of both pulse generation in the oscillator and propagation in the amplifier provide very good agreement with the experiments and allow us to identify its limitations.      

脉冲放电时碱锰电池电极电位的同步测定

通过在LR6电池正极开孔,以Hg-HgO电极为参比电极,KOH溶液为电解液,获得了普通碱锰电池和高功率碱锰电池在高功率放电过程中正、负极电位随时间的变化曲线.具有高功率放电性能的电池更好地抑制了电池脉冲电压降幅及其增大速率,尤其是在电池放电的中、后期,更好地抑制了正、负极电位下降(上升)的幅度及上升速率.     

Improvement of microwave power from a virtual cathode oscillator and its repetitive operation using a metal mesh anode

A virtual cathode oscillator with a stainless‐steel mesh anode of various transparencies and wire diameters was studied experimentally for the enhancement of microwave power and its repetitive operations. The maximum microwave power observed was about 20 MW at 12 GHz for a diode voltage of 250 kV and an electron beam current of 39 kA using an anode mesh with wire diameter of 0.22 mm and a transparency of 67%. The microwave emission was enhanced by decreasing the mean angle of beam scattering when a mesh of smaller wire diameters was used in the anode. The increased transparency of the fine mesh also contributed to the enhancement of the microwave emission. Use of the mesh anode afforded the operation in several repetitive shots. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(2): 1–10, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10259     

中速线上T5大功率荧光灯的阴极分解技术

本文针对中速线上大功率荧光灯阴极分解工艺出现的问题,从灯丝结构、分解工艺和4个分解区域的合理调整等3方面作了详细的论述,最后提出了一种在阴极辉放前采用电流沉降法减少产生黄圈的方法。     

一种基于有界不确定性和扰动估计器的大功率充电桩控制策略

大功率充电桩接入电网是实现多电压等级电动汽车充放电的关键设备,但因电动汽车的即插即用需求和充电功率冲击特性,大功率充电桩接入将对电网运行稳定性带来挑战。提出基于不确定性和扰动估计器（uncertainty and disturbance estimator, UDE）的大功率充电桩控制策略。首先,在大功率充电桩双主动全桥换流器（dual active bridge, DAB）模块采用虚拟直流电机控制策略,实现对直流电压的基本控制。然后,考虑电动汽车投切对电网稳定运行的影响,基于LC滤波器建立UDE补偿控制环节,对滤波单元动态误差进行反馈,将其输出量作为补偿分量,实现对直流母线电压的补偿控制,从而有效提升直流电压稳定性。最后,基于PSCAD/EMTDC搭建充电桩系统仿真模型,其仿真结果验证了所提控制策略的可行性。     

Coherent Power Combination of Semiconductor Lasers Using Optical Phase-Lock Loops

Heterodyne optical phase-lock loops (OPLLs) enable the precise electronic control over the frequency and phase of a semiconductor laser (SCL) locked to a ldquomasterrdquo reference laser. One of the more interesting applications of OPLLs is the creation of coherent arrays by locking a number of ldquoslaverdquo SCLs to a common master laser. In this paper, we demonstrate the coherent power combination of various high-power semiconductor lasers using OPLLs in both the filled-aperture and tiled-aperture configurations. We further demonstrate the electronic control over the phase of each individual SCL using a voltage-controlled oscillator. It is feasible to combine a large number of SCLs using this approach, leading to compact, efficient, and cost-effective high-power and high-radiance optical sources.     

基于瞬时实功率和瞬时虚功率的谐振接地系统单相接地选线新方法

谐振接地系统发生单相接地故障时故障信号复杂且暂态信息丰富。本文基于瞬时功率理论,提出了采用瞬时实功率和瞬时虚功率的复合选线新方法。谐振接地系统发生单相接地故障时,与健全线路不同,故障线路由于消弧线圈的补偿作用将在接地电流中产生暂态衰减直流分量,通过瞬时实功率和瞬时虚功率分析表现为明显的工频衰减振荡特征。文章确定50Hz为瞬时功率分析的特征频率,通过分别计算故障时各线路瞬时实功率和瞬时虚功率,进一步分解出其振荡分量,综合比较特征频率上各线路瞬时实功率及瞬时虚功率振荡分量的大小来构造选线算法从而检出故障线路。该方法利用暂态信息,多判据复合、不涉及相位分析、实现容易、可靠性高。仿真表明该方法有效。     

Analytical subthreshold current and subthreshold swing models of short-channel dual-metal-gate (DMG) fully-depleted recessed-source/drain (Re-S/D) SOI MOSFETs

In this paper, analytical subthreshold current and subthreshold swing models are derived for the short-channel dual-metal-gate (DMG) fully-depleted (FD) recessed-source/ drain (Re-S/D) SOI MOSFETs considering that diffusion is the dominant current flow mechanism in subthreshold regime of the device operation. The two-dimensional (2D) channel potential is derived in terms of back surface potential and other device parameters. The so called virtual cathode potential in term of the minimum of back surface potential is also derived from 2D channel potential. The virtual cathode potential based subthreshold current and surface potential based subthreshold swing model results are extensively analyzed for various device parameters like the oxide and silicon thicknesses, thickness of source/drain extension in the BOX, control to screen gate length ratio and channel length. The numerical simulation results obtained from ATLAS \(^{\text{ TM }}\) , a 2D numerical device simulator from SILVACO Inc have been used as a tool to verify the model results.     

多电平变换器PWM控制技术研究现状综述及最新进展

近年来,多电平变换器成为高压、大功率电力电子系统应用领域的一个研究热点,而多电平脉宽调制PWM(pulse width modulation)控制方法是多电平变换器研究领域的核心问题之一.首先,阐述了3种载波PWM控制方法,并根据不同的控制指标介绍了各类优化载波PWM控制方法;其次,介绍了传统空间矢量脉宽调制SVPWM...     

Duffing振子信号检测方法用于配电网单相故障接地保护

Duffing振子信号检测技术利用混沌系统的分岔特性来检测外界信号，将待测信号作为Duffing方程周期策动力的摄动，利用初值敏感性可以获得很高的测量灵敏度和良好的抗噪性能。基于Duffing振子信号检测技术提出一种新型的单相接地故障选线方法。故障后故障线路和非故障线路零序电流将使Duffing振子系统分别处于大周期或混沌状态，据此可以选出故障线路，从而将选线问题转化为待测故障信号从无到有的敏感检测问题，简化了选线过程，抗噪性能好，提高了接地保护的灵敏度。文中给出了该方法的具体实现步骤。采用虚拟仪器技术，开发了基于混沌选线方法的小电流接地系统单相接地故障选线仪。实验室物理模拟实验和现场录波数据分析结果证明了该方法的可行性和有效性。     

PPMgLN-Based High-Power Optical Parametric Oscillator Pumped by Yb $^{{bm 3}{bm +}}$-Doped Fiber Amplifier Incorporates Active Pulse Shaping

We report a periodically poled magnesium-oxide-doped lithium niobate (PPMgLN) based optical parametric oscillator (OPO) pumped by a diode-seeded, linearly polarized, high-power, pulsed, ytterbium fiber master oscillator power amplifier (MOPA). Using adaptive pulse shaping of the seed laser (using an external modulator), we demonstrate a reduction in the impact of dynamic gain saturation and optical Kerr/Raman nonlinearities within the fiber MOPA, obtaining shaped signal and idler pulses at the OPO output and reduced spectral bandwidths. A maximum average output power of 26.5 W was obtained from the MOPA at 1062 nm. An output power as high as 11 W from the OPO at an overall slope efficiency of 67% was achieved, with 2.7 W of output power obtained at a wavelength of 3.5 mum. Our experiments were pump-power-limited and considerable scope remains for further power scaling of such OPOs using this approach.     

无电网电压传感器三电平PWM整流器研究

在大功率三电平整流器应用中,为降低成本、提高性能,研究了一种无电网电压传感器三电平PWM整流器。在分析其数学模型的基础上,采用三电平SVPWM简化算法,将传统两电平电压空间矢量控制算法应用于三电平,并结合一种新颖的虚拟磁链观测器,提出了基于虚拟电网磁链定向的三电平PWM整流器矢量控制策略,在双三电平变频器系统中对其进行实验研究。实验结果表明,该三电平PWM整流器可较好地稳定直流母线电压,提高整流器功率因数,并具有良好的动静态特性。     

Vacuum insulation and discharge phenomena in high-power deviceswith magnetic confinement of electron flow

Results of the experimental investigation of processes determining vacuum insulation maintenance and discharge phenomena in high-power crossed-field and electron-beam devices are presented. Data from crossed-field devices on accumulation and steady-state parameters of the space charge between cold cathode and anode, spatial, temporal and energy characteristics of electron flows onto surrounding electrodes are given. Techniques of gun breakdown prevention and formation of a dense nonrelativistic long-pulsed electron beams with energy density ⩽100 kJ/cm² are described, as well as the effect of RF discharge development on the beam transport in this system. Models of observed phenomena considering the effect of nonuniform electromagnetic fields, oscillatory processes and generation of secondary particles accompanying electron bombardment of electrodes are also proposed     

An ultra-line-narrowed high-power F/sub 2/ laser for dioptric design microlithography exposure tools

An ultra-line-narrowed high-power and high-repetition rate F/sub 2/ laser system has been developed for 157-nm microlithography exposure tools with dioptric projection design. The injection locked system (ILS) consists of a low-power seed laser with ultra-narrow spectral linewidth and a high-gain amplifier. More than 25-W output power, a spectral linewidth below 0.2 pm full-width at half-maximum (FWHM) and an energy stability (3-sigma) below 10% have been obtained at a 5-kHz repetition rate and for a delay time range between the two laser stages of about 15 ns. Directly compared with a master oscillator power amplifier system, the ILS had a better performance related to output energy, energy stability, and laser pulse duration.     

Full Measuring System for Copper Electrowinning Processes Using Optibar Intercell Bars

An evolved Optibar intercell bar for copper electrowinning processes with current sensing capabilities is presented. This technology upgrades the advantages of the conventional Optibar by providing a complete measuring system using magnetic sensors inside the capping board. To enhance reliability and simplicity, only half of the intercell currents are physically measured. This is accomplished using adaptive neurofuzzy inference system networks to calculate the current flowing through nonsensored connecting Optibar segments using virtual sensors. This way, process cathode currents are available online enabling myriad of key process computations; i.e., cathode harvest time, weight at harvest, current dispersion among cathodes, energy consumption and process efficiency, and online setting of optimum process current level based on the ability to detect and locate metallurgical short-circuits events. In this paper, this task is accomplished using a short-circuit diagnosis algorithm based on the recognition of current distribution patterns that characterizes the phenomena using artificial neural networks. The technology employed to implement the system is completely embedded in the bar to ensure compatibility with the process environment. From the outside, Optibar add-ons are hidden and do not disrupt the operation. On site industrial data proved that cathode current measurements exhibit an average absolute error lower than 2% with a dispersion lower than 1.6%. Finally, the algorithm developed for short-circuit diagnosis exhibits a success rate of 98% or better.     

基于虚拟同步策略的电动汽车V2G技术在多能互补系统中的研究及应用

为解决大规模电动汽车单向充电造成的电网冲击和线路负荷过重问题,开展了电动汽车V2G技术在多能互补系统中的应用研究。首先,对比分析了多种典型的多能互补系统拓扑结构的技术优缺点,在基于共交流母线的多能互补系统中应用V2G技术。其次,提出基于虚拟同步机的V2G自主有功-无功控制策略,优化设计虚拟惯量、阻尼系数等关键参数,模拟传统发电机组的机电暂态特性,实现系统自主调压调频,解决光伏发电的间歇性和随机性带来的电网指标波动问题。然后,搭建了典型的多能互补系统,并进行仿真验证。结果表明,基于虚拟同步机的V2G设备能主动跟踪并网点频率、电压变化,及时提供有功、无功功率支撑,有效保障电网运行的稳定性。最后,研制了基于虚拟同步策略的500 kW大功率V2G设备,并在示范项目中成功应用,验证了所提方法的有效性。     

Parallel inverter control using different conventional control methods and an improved virtual oscillator control method in a standalone microgrid

This paper develops a multi-timescale coordinated operation method for microgrids based on modern deep reinforcement learning. Considering the complementary characteristics of different storage devices, the proposed approach achieves multi-timescale coordination of battery and supercapacitor by introducing a hierarchical two-stage dispatch model. The first stage makes an initial decision irrespective of the uncertainties using the hourly predicted data to minimize the operational cost. For the second stage, it aims to generate corrective actions for the first-stage decisions to compensate for real-time renewable generation fluctuations. The first stage is formulated as a non-convex deterministic optimization problem, while the second stage is modeled as a Markov decision process solved by an entropy-regularized deep reinforcement learning method, i.e., the Soft Actor-Critic. The Soft Actor-Critic method can efficiently address the exploration–exploitation dilemma and suppress variations. This improves the robustness of decisions. Simulation results demonstrate that different types of energy storage devices can be used at two stages to achieve the multi-timescale coordinated operation. This proves the effectiveness of the proposed method.