基于FPGA控制的多电平电压质量调节装置研究

研究了基于4 H桥级联9电平结构的电压质量调节装置,采用现场可编程门阵列和数字信号处理控制,针对电力系统中出现的各种电压质量问题,提供了综合的解决方案。该方案能够对电力系统中发生的电压暂升、电压暂降、电压谐波、电压波动等问题进行复合补偿,从而保证系统的电压质量。最后设计研制了0.1 MVA/400 V低压样机,对于各种电压质量问题进行试验,并对数据结果进行分析,结果表明本装置可以有效补偿各种电压质量问题。     

Ultra Storage-Efficient Time Digitizer for Pseudorandom Single Photon Counter Implemented on a Field-Programmable Gate Array

Pseudorandom single photon counting is a novel time-resolved optical measurement method, which is advantageous over convention techniques in terms of data-acquisition speed and system cost. As a critical component of the pseudorandom single photon counter, the photon arriving time digitizer should be storage efficient for a high photon counting rate, while maintaining good time accuracy. We report an ultra storage-efficient time digitizer for a pseudorandom single photon counter in this paper, which is based on the asynchronous serial communication and can store the arriving time of every photon in 1-b memory space. In addition, a novel comb-wave modulator is proposed to achieve the dc balance required for asynchronous serial communication. Our prototype implemented on field-programmable gate arrays provides a time resolution of 400 ps. It can register up to 4.2-Giga photon arriving time tags with 1024 $times$ 32-b memory space.      

利用现场复杂可编程门阵列产生PWM控制脉冲的方法

以有源滤波系统中PWM脉冲的生成原理为基础 ,阐述了一种基于DSP -FPGA数字系统的PWM控制脉冲生成方法 ,并给出了仿真及实验结果     

Differential Near-Field Scanning Optical Microscopy Using Sensor Arrays

In this paper, we introduce a new aperture-type near-Held scanning optical microscopy (NSOM) imaging concept that relies on specially designed large-area (e.g. >200 nm times 200 nm) aperture geometries having sharp corners. Unlike in conventional NSOM, the spatial resolution of this near-field imaging modality is not determined by the size of the aperture, but rather by the sharpness of the corners of the large aperture. This approach significantly improves the light throughput of the near-field probe and, hence, increases the SNR. Here, we discuss the basic concepts of this near-field microscopy approach and illustrate both theoretically and experimentally how an array of detectors can be utilized to further improve the SNR of the near-field image. The results of this work are particularly relevant for imaging of biological samples at a spatial resolution of < 50 nm with significantly improved image quality.     

Fabrication of Ferroelectric Gate Memory Device Using BLT/HfO2/Si Gate Structure

Ferroelectric gate FET's with BLT/HfO₂ structure were fabricated on 5-inch-scale Si wafer using well-refined CMOS compatible 0.8 μm-based fabrication processes for the first time. We obtained excellent device characteristics and good memory operations of the fabricated n-ch and p-ch MFIS-FET's, in which the memory window and on/off drain current ratio of typical p-ch memory device were measured to be 1.5 V at V_G of ±5 V and 8 orders-of-magnitude, respectively. We also confirmed by evaluating the gate voltage and gate size dependences of device properties that the fabricated devices showed quantitatively reasonable ferroelectric memory operations.     

用单片机实现闸阀门开度的检测

用单片机实现闸阀门开度检测,实现PLC与闸阀门开度检测装置之间的连接。不仅具有成本低、PLC编程简单的特点,而且具有高可靠性。     

磁传感器阵列测量大电流实验系统

电力系统中现有的大电流测量设备往往存在体积大、测量范围窄、绝缘困难等缺陷,故提出了使用磁传感器阵列测量交直流大电流的思路,该测量方法具有体积小、成本低、非接触测量、交直流通用、可数字化输出等优点。为了分析在实际系统中影响该方法测量精度的若干因素,利用基于离散傅里叶变换（DFT）的多相大电流测量算法,设计了大电流实验测量装置,并使用该装置进行了一系列不同母排形状的测量实验,并对各测量环节产生的误差来源进行了理论分析。实验结果验证了本测量方法的有效性。     

Analysis of Gate Dielectric Stacks Using the Transmitting Boundary Method

We present simulations of tunneling current through layers of high-κ dielectrics using the Tsu-Esaki model and the quantum transmitting boundary method (QTBM) to estimate the transmission coefficient. In contrast to transfer-matrix based methods, which suffer from numerical instabilities due to rounding errors, the QTBM is numerically stable even for large stacks and is suitable for implementation in device simulators. The method is used to investigate the tradeoff between conduction band offset and permittivity in alternative high-κ materials.     

磁传感器阵列测量瞬态电流的新算法

不借助如聚磁环等辅助装置,直接利用磁传感器组来测量载流导体周围的磁场,进而反算待测电流是电力系统大电流测量的一种新思路.为了快速计算电流,尤其是电力系统中常见的瞬态电流,同时确保测量的准确性,文中研究了测量频带内磁场分布的动态特性,在时域中建立了基波电流与磁场幅值对应关系的瞬态电流计算模型.以三相矩形母排系统为例,研究...     

磁传感器阵列测量瞬态电流的新算法

不借助如聚磁环等辅助装置,直接利用磁传感器组来测量载流导体周围的磁场,进而反算待测电流是电力系统大电流测量的一种新思路。为了快速计算电流,尤其是电力系统中常见的瞬态电流,同时确保测量的准确性,文中研究了测量频带内磁场分布的动态特性,在时域中建立了基波电流与磁场幅值对应关系的瞬态电流计算模型。以三相矩形母排系统为例,研究了该测量模型适用的磁传感器组放置区域,并分析了误差的来源。最后利用实验验证了该模型的有效性。     

一种新型Halbach阵列永磁振动发电机的设计与输出特性分析

给出了一种永磁振动发电机感应电动势的计算公式,设计了一种新型Halbach阵列永磁振动发电机,机体两侧分别固定了两组永磁体,内部6个线圈串联。采用有限元法,与普通Halbach阵列和传统永磁振动发电机进行了对比分析,新型Halbach阵列的应用大幅度提升了振动发电机的性能。正弦规律振动的振源频率为10 Hz,振幅为3 mm时,新型振动发电机的最大输出功率为355.85 m W,开路电压有效值为6.402 9V。最后,对线圈相对永磁体的位置进行了优化,最大输出功率达到了414.81 m W,进一步提升了16.57%,此时开路电压有效值为7.036 6 V。     

The Advantages of Using Saturable DC Series Motors Fed from Solar Photovoltaic Arrays

This paper presents a method for increasing the daily output mechanical energy supplied by DC motors directly connected to solar cell arrays (SCA). Without any interfacing circuitry between the PV-array and the DC series motor, an increase of about 10% in the mechanical energy can be achieved. The procedure is based on the use of series DC motors with nonlinear magnetic circuits so that these motors will be driven into their saturation region during their normal operation. It will be shown that through properly selecting the parameters of the motor’s magnetization characteristics (initial mutual inductance and the flux saturation level), an improved matching between the PV-array and the DC motor will be possible.     

平移法整体迁移铁塔的应用

介绍在地形环境满足要求的情况下,用平移法整体迁移铁塔的具体施工方法。实际应用也证明,用平移法整体迁移铁塔的停电时间短,安全性高,节约投资,经济效益和社会效益显著,值得相关部门的推广和应用。     

选择区域外延槽栅结构GaN常关型MOSFET的研究

高性能GaN常关型功率开关器件的实现是目前研究的热点。槽栅结构GaN常关型MOSFET以其栅压摆幅冗余度大、栅极漏电流小等优势受到广泛关注。制备槽栅结构GaN常关型MOSFET需要的刻蚀方法会在栅极沟道引入缺陷,影响器件的稳定性。首先,提出选择区域外延方法制备槽栅结构GaN常关型MOSFET,期望避免刻蚀对栅极沟道的损伤;再通过改进选择区域外延工艺(包括二次生长界面和异质结构界面的分离及抑制背景施主杂质),使得二次生长的异质结构质量达到标准异质结构水平。研究结果表明,选择区域外延方法能够有效保护栅极导通界面,使器件具备优越的阈值电压稳定性;同时也证明了选择区域外延方法制备槽栅结构GaN常关型MOSFET的可行性与优越性。     

用变时基技术进行弧形钢闸门的模态试验分析

使用变时基传递函数模态分析技术对龙羊峡水电站表孔溢洪道弧形钢闸门进行模态试验和分析,极大地提高了大型结构的传递函数的分析精度.试验结果表明,龙羊峡水电站1、2号门具有相似的振动形态.     

遗传算法在水轮机非固定模式导叶关闭规律中的应用

水轮机非固定模式导叶关闭规律是指按水轮机初始工况参数适时地确定最佳导叶关闭方式。这种适时的水轮机导叶关闭方式对于水电站大波动过渡过程具有较好的参数控制作用,能在不改变任何基础设施的前提下降低水电站过水系统最高水锤压力和机组转速,给水电站的运行带来较大的经济效益。在对非固定模式导叶关闭规律的优化中遗传算法有较高的优化效率,其中主要表现在算法简单、全局搜索性好、收敛性高、优化结果稳定。     

用变时基技术进行弧形钢闸门的模态试验分析

使用变时基传递函数模态分析技术对龙羊峡水电站表孔溢洪道弧形钢闸门进行模态试验和分析,极大地提高了大型结构的传递函数的分析精度。试验结果表明,龙羊峡水电站1、2号门具有相似的振动形态。     

Calculation of Direct Tunneling Current through Ultra-Thin Gate Oxides Using Complex Band Models For SiO2

We report the calculation of gate leakage currents through the ultra-thin gate oxides (2.6–3.4 nm) in MOSFETs. We simulate J-V characteristics for the direct tunneling of valence electrons and inversion layer holes, which are measured using a charge separation technique. A two-band model is employed to express the complex band structure of the gate oxide, and its validity is discussed by calculating the complex band structure of -cristobalite based on the second nearest neighbor sp ³ s* tight-binding scheme.