峰值电流型PFC Boost变换器斜坡补偿方法研究

PFC Boost电路中由于输入电压的时变性造成输入电流在过零附近产生分岔现象,本文针对该现象,以电流连续模式（CCM）下峰值电流型PFC Boost变换器的精确时变模型为基础,研究了抑制分岔的斜坡补偿方法,通过SIMULINK仿真验证,表明输入电流分岔现象得到消除,接近输入电压波形,改善了PFC Boost变换器的性能。     

无直流电压传感器的单相APFC变换器

文章对一种只检测交流输入电压而不需要检测输出直流电压的简化单相PFC变换器进行了理论分析和研究。在构建控制电路时,不需要常规PFC变换器中的输出电压传感器和输入电流传感器。PFC变换器的主电路为整流电路的直流侧接一级Boost电路。在控制电路中,使用电感L、等效负载电阻Rd等电路参数产生正弦电流波形基准,输出电压直接由控制量Kd(=Ed/Ea)来调节。通过控制,可以得到恒定的直流输出电压和与交流输入电压同相位的正弦电流波形。仿真结果证明了该变换器的可行性。     

一种改善PFC变换器输入电流过零畸变的方法

功率因数校正（PFC）变换器普遍存在输入电流在输入电压过零点附近发生畸变的现象。文中详细分析了PFC变换器输入电流在输入电压过零点附近产生畸变的原因,指出了Boost PFC变换器的输入电流超前于输入电压是导致位移因数不为1和输入电流过零畸变的主要原因;提出了根据输入电流在输入电压过零时刻的值实时修正参考输入电压的初相角,以改善PFC变换器输入电流过零畸变的数字控制方法。仿真结果证明了文中所提出的方法的有效性,特别是在400Hz输入电压下有很好的效果。     

一种Boost型PFC电路在DCM下的恒频控制方案

通过对Boost型变换器在不连续导电模式DCM(Discontinued Conduction Mode)下平均电感电流的分析,得到了在恒 频状态下实现功率因数校正 PFC ( Power Factor Correction)时,功率开关管所需的开启时间与输入、输出电压之间的数学关系,并结合实际电路设计,提出了一种PF...     

一种新型的基于航空电网的高功率因数校正器

研究了一种基于航空电网的高功率因数Boost PFC变换器,与以往采用的乘法器控制方法不同的是,该变换器采用新型单周期控制方法。文中分析了该变换器的工作原理,给出了系统电压环的结构模型和设计过程。仿真和实验结果证明了在输入电源频率较高场合,单周期控制Boost PFC变换器具有良好的性能。     

MPPT控制Boost变换器的一种软开关实现策略

提出了最大功率点跟踪MPPT(Maximum Power Point Tracking)控制Boost变换器的一种软开关实现策略:将MPPT控制Boost变换器设计在断续导通模式DCM(Discontinuous Conduction Mode)下。首先推导了MPPT控制Boost变换器的等效负载,然后借助工作模式分析推导得到输入电感的临界值。设计输入电感为临界值就可以使得变换器在全输入电压范围内工作在DCM模式下,开关器件实现自然的软开关。最后,在PSIM软件中完成了仿真验证。     

开关电源Boost变换器输出纹波的仿真研究

文章在分析典型DC-DC变换拓扑结构的基础上,建立了降压型（Boost）DC-DC变换器的PSpice仿真模型。在三种工作模式下,针对输入电压、电感和负载电阻对输出电压纹波都有不同程度的影响,对Boost变换器输出纹波电压的影响因素进行了分析。其结论为Boost型DC-DC变换器的设计和研制提供了理论依据。     

多相交错并联Boost功率因数校正器的研究

针对开关电源在传统的Boost功率因数校正电路中有着明显的开关损耗,使得电路具有较高成本和低效率。文中在传统单相Boost变换器的基础上,采纳多通道交错并联技术来进行有源功率因数校正的主电路拓扑。以三相交错并联Boost变换器为例,分析其工作过程,并通过仿真实验证明了多相交错并联Boost PFC变换器具有减小输入电流纹波和输入电感值,以及提高变换器的效率等优点。     

BFC直流变换器在光伏发电系统中的应用研究

光伏发电系统中输出电压随光强变化波动较大,为保证正常并网逆变,需要一种高增益的直流变换器将光伏输出电压提升到常规直流母线电压。这里主要研究一种基于Boost拓扑、Flyback拓扑的升压反激式变换器(BFC)在太阳能光伏发电系统的应用。BFC将Boost拓扑与Flyback拓扑输入并联、输出串联,反激拓扑中的初级线圈电感同时作为Boost拓扑的输入电感,变压器的漏感能量得到了利用。仿真结果表明,新型BFC直流变换器应用于光伏发电系统时,具有提高输出电压增益,减小电压纹波,跟踪效果更好等优点。     

一种带自适应斜坡补偿的PCM控制Boost变换器

设计了一种带自适应斜坡补偿的峰值电流模式(PCM)控制Boost变换器。采用一种低功耗自适应斜坡补偿电路,使得升压(Boost)变换器能够实现宽输出范围和高带载能力。在此基础上,提出了一种应用于Boost变换器的电感电流采样电路,该电路实现了高采样速度和高采样精度,且具备全周期的电感电流采样特点。变换器基于SMIC 180 nm BCD CMOS工艺设计。仿真结果表明,该带自适应斜坡补偿的PCM控制Boost变换器输入电压转换范围为2.8 V～5.5 V,输出电压转换范围为4.96 V～36.1 V,最大输出负载电流高达5 A。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks