低压大电流大功率软开关全桥变换器拓扑结构分析

分析研究了低压大电流全桥变换器电路拓扑结构。分别介绍了功率变压器初级移相控制零电压(ZVS)PWM和移相控制零电压零电流(ZVZCS)PWM软开关全桥变换器主电路拓扑结构,以及功率变压器次级适宜采用的不同电路拓扑形式,并对其优缺点进行了对比分析。文中简要说明了在变换器输入级加入功率因数校正环节的必要性。     

基于OPNET的局域网拓扑建模仿真

为分析比较局域网中星形,环形和树形3种典型的点到点拓扑的优缺点,运用优化网络工程工具(Optimized Network Engineering Tools,简称OPNET)建立3种拓扑模型,并对其性能仿真.通过分析仿真数据,对3种拓扑的延时,通信量和负载进行比较,给出了3种拓扑各自优缺点,从而为网络规划选择的最佳拓扑提供了技术参考.     

XL75型变频器用移相变压器的结构原理分析

介绍了一种与国外生产的高压变频器配套的移相变压器,通过与目前市场上通用的移相变压器的线圈方式进行对比,分析其内部绕组接线结构,构建变压器绕组的相量图,进一步分析其工作原理及制造技术的优缺点。     

17～21 GHz 6 bit高精度数字移相器的设计

采用0.15μm GaAs赝配高电子迁移率晶体管（PHEMT）工艺,研制了一款17～21 GHz 6 bit高精度数字移相器。该移相器5.625°移相单元采用嵌入式LC拓扑结构,11.25°和22.5°移相单元采用嵌入式全通网络拓扑结构,45°、90°和180°移相单元采用开关选择型多阶高、低通网络拓扑结构;驱动单元采用直接耦合场效应晶体管逻辑（DCFL）结构。测试结果表明,在17～21 GHz工作频率内,该移相器插入损耗的绝对值小于8.5 d B,均方根相位误差（RMS）值小于1.8°,移相寄生调幅在-0.8 d B和0.6 d B之间,电压驻波比（VSWR）小于1.5。     

Ku波段五位数字移相器的设计

本文设计了11.4～12.8GHz频段内五位数字移相器的电路拓扑.采用GaAs MESMET技术建立封须开关模型,对高/低通网络型网络拓扑及场效应管嵌入桥π型电路的移相器拓扑进行仿真,结果表明,当中心须率在12GHz时,达到精确的移相度数,在整个频带内插入损耗小于2dB,移相精度(RMS)小于30,移相前后电压驻波比小于1.35.     

一种新型单层微带反射阵天线单元的分析

提出了一种由圆形与圆环形两种结构混合组成的新型单层微带反射阵天线单元,系统地归纳了衡量移相曲线性能优劣的四个参量：相移范围、线性度、曲线斜率以及相位带宽,定义了移相曲线性能函数.采用基于RWG基的谱域矩量法分析了不同几何参数对单元移相曲线性能的影响,通过选择合适的几何参数,最终可使移相曲线的相移范围超过360°且曲线变化平缓并具有高度线性性.     

同步移相干涉的测量性能

详细分析了一种基于二维正交光栅衍射的同步移相干涉测量系统的组成结构,包括干涉系统、空间分光部件、偏振移相部件以及图像采集与处理系统。选择了二维正交透射光栅的四个衍射级次的光束作为测试光,理论和实验都证明这种方案具有良好的分光效果;用偏振方向依次改变45°的四片偏振片构成偏振阵列作为移相器件,并根据空间一致性要求,分割得到依次具有90°移相的四幅独立干涉图,获得了较高的移相精度;在幅频积低于100 Hzλ的振动环境中,系统测量重复性的峰谷值优于0.02λ,可以用于一般的在线检测和动态测量。     

网络防火墙原理及其拓扑结构分析

阐述了防火墙技术原理,分析了防火墙的几种典型的拓扑结构及各自优缺点,并指出一个较完善的网络系统应是防火墙技术与其它网络安全技术的结合。     

一种移相电路的设计

移相电路的应用很广,如闸流管控制点火时间;相敏整流或相敏放大电路中要求栅极和板极电压在初始时具有一定的相位关系;以及在自动控制或测量放大等电路中都需要移相电路.一般对移相电路的要求有四:第一,具有大的移相幅度;第二,输出电压相移变化时幅度不变或变化很小;第三,能给出一定的功率;第四,效率高.这四要求的主次视具体情况而定,如要求大功率输出时,以后两项要求为主;但在小功率输出时以前两项要求为主.下面来介绍一种常见的移相电路(图1)的设计法,这电路的特点是在移相幅度很大时,输出电压变化很小,且能输出一定的功率.     

Internet拓扑建模技术的研究

如何描述了被仿真网络的拓扑结构是网络仿真的基础性问题.对于大规模异构性动态性发展的非集中性的Internet来说,描述其拓扑结构并不是一件容易的事情.Internet拓扑建模至今仍然是计算机网络研究领域中的热点问题.文中对几种Internet拓扑建模进行了研究与分析,比较了他们的优缺点,指出了存在的问题,最后给出Waxman算法的具体实现.     

DSP控制移相全桥DC-DC变换器的研究与设计

随着电力电子技术的日渐成熟,开关电源越来越朝着小型化,高效化的方向发展.DC-DC变换器是以移相全桥为主电路,其核心的数字化控制是DSP来实现的.移相全桥DC-DC变换器具有开关损耗小,效率高和输出电流纹波小等优点.本文内容包括硬件电路设计、软件的实现及通信协议等.     

零电流开关大功率DC/DC双全桥变换器设计

提出了一种基于双全桥结构的单向零电流开关大功率（兆瓦级）DC/DC变换器,该变换器通过采用两个全桥变换器来实现零电流开关,实现了较低的功率损耗和输出滤波电感。为了验证提出的变换器在大功率应用中的有效性,构建了小型样机并在大功率直流电网进行了实际测试。实验证明,相比传统的两种单向大功率全桥变换器,提出变换器所需的滤波电感和半导体器件的功率损耗均较少,分别仅为1.72mH和924.5kW。     

48kW大功率高频开关电源的研制

主要介绍48kw大功率高频开关电源的研制。阐述国内外开关电源的现状．分析全桥移相变换器的工作原理和软开关技术的实现。软开关能降低开关损耗,提高电路效率。给出电源系统的整体设计及主要器件的选择。试验结果表明,该装置完全满足设计要求,并成功应用于电镀生产线。     

A new ZVS bidirectional DC-DC converter for fuel cell and battery application

This paper presents a new zero-voltage-switching (ZVS) bidirectional dc-dc converter. Compared to the traditional full and half bridge bidirectional dc-dc converters for the similar applications, the new topology has the advantages of simple circuit topology with no total device rating (TDR) penalty, soft-switching implementation without additional devices, high efficiency and simple control. These advantages make the new converter promising for medium and high power applications especially for auxiliary power supply in fuel cell vehicles and power generation where the high power density, low cost, lightweight and high reliability power converters are required. The operating principle, theoretical analysis, and design guidelines are provided in this paper. The simulation and the experimental verifications are also presented.     

An Improved Single Stage Phase Shifted Control Based AC–DC PFC Converter for Wireless Applications

Recently, many researchers has more attention in a single stage AC to DC converter features and DC to DC regulator are extensively used into low power applications. When compared with the two stage conventional method over the Single stage converter has a simple design and utilize only less components. Therefore, this task has been used in this paper as a prposed work of AC–DC single stage converters combine a converter front end with DC–DC back end converter. This proposed work has been improved single stage power factor correction (PFC) converter based on phase-shifted controller for wireless Power applications. The proposed technique employed to develop the improved converter for task of an extensive series of voltage outputs with rippleless outcomes in low frequency, that shows the high essential in battery application and the PFC duty ratio restriction is eradicated. Similarly, DC–DC stage operation are designed in a related way of conventional full bridge phase shifted converter. Accordingly, the proposed technique of improved converter of this paper will achieves better efficiency compared with other conventional techniques and it has been prove more efficient for many Industrial applications, it has been discussed in result section clearly. The experimental results of proposed improved converter proves that it is potential to extend high power single stage converter with good power factor, conversion characteristics and efficiency.

     

一种全数字控制两级级联大功率开关电源

设计了一种基于数字信号处理(DSP)的全数字控制两级级联大功率开关电源。在电路结构方面,采用了降压型和全桥式的变换器结构,其中,降压电路的占空比可随输出电压而调节,全桥电路能实现输入级与输出级的全隔离。在电路控制方面,采用数字比例-积分-微分(PID)控制技术,提升了系统的闭环控制速度和精度。该功率开关电源基于DSP的控制方法,构建了电源的控制系统。仿真及测试结果表明,基于DSP设计的开关电源具有稳定的性能和较高的效率,转换效率可达92%。     

A Novel Two Phase Nonisolated Full Bridge With Shared Primary Switches

In this paper, a new full bridge topology called the two-phase nonisolated full bridge (NFB) is introduced. The proposed two-phase NFB can handle the same power as two parallel NFB converters, but with less MOSFETs, better efficiency, and lower cost. To demonstrate the advantages of the new topology, two prototypes are built on a 12-layer 2-oz PCB board, one with four inductors, the other with three inductors. Two prototypes achieve 82.3% and 82% efficiency at 1-MHz full load (1 V/80 A), respectively. This is compared to 81.8% efficiency of the two paralleled NFB converters. At light load (1 V/10 A), a 4% efficiency improvement is achieved. Experimental results demonstrate that compared with two paralleled NFB converters, the two-phase NFB converter is able to achieve better efficiency with a simplified power train circuit and reduced cost.      

Network Control System (NCS) for Performance Improvement of Dual Converter Power Supply System Using Adaptive Inverse Dynamic Mode (AIDMC) Control Technique

With recent advances in power electronics, dual converter power supply based electric variable-speed drives are significantly used in many industries uses. Power electronic motor drivers are becoming able to efficiently read the inflexible characteristics of DC motor to prerequisites the load. By controlling the input armature voltage, the DC motor speed automatically changed. Half-bridge converter, semi converter, full bridge converter and dual converter are some of the thyristor controlled rectifier circuits are widely used in variable speed drives. In This work presents single phase dual converter power supply system based on adaptive inverse dynamic mode control (AIDMC) technique. The efficient dual converter control solution for industrial network control system (NCS) is proposed based on the industrial grade requirements, designed for low to high voltage operation. As the era of connecting the devices with the cloud is being increased gradually, the proposed method uses an NCS protocol for monitoring as well as controlling the dual converter system. The proposed method provides us the control over forward and reverse rotation, forward and reverse regeneration. From the simulation results, the proposed result offers variable DC voltage which is capable of four quadrant operation of the drive in a speed-torque plane by using MATLAB Simulink environment. A hardware setup also developed to validate the simulation. Over 96% accuracy achieved full load condition for proposed dual converter power supply system based on AIDMC controller.     

Novel zero-voltage and zero-current-switching full bridge PWMconverter using transformer auxiliary winding

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) pulse width modulation (PWM) converter is proposed to improve the demerits of the previously presented ZVZCS-FB-PWM converters, such as use of lossy components or additional active switches. A simple auxiliary circuit which includes neither lossy components nor active switches provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS for lagging-leg switches. Many advantages including simple circuit topology, high efficiency, and low cost make the new converter attractive for high power (>2 kW) applications. The operation, analysis, features and design considerations are illustrated and verified on a 2.5 kW, 100 kHz insulated gate bipolar transistor (IGBT) based experimental circuit     

A Novel Soft-Commutating Isolated Boost Full-Bridge ZVS-PWM DC–DC Converter for Bidirectional High Power Applications

A soft-commutating method and control scheme for an isolated boost full bridge converter is proposed in this paper to implement dual operation of the well-known soft-switching full bridge dc/dc buck converter for bidirectional high power applications. It provides a unique commutation logic to minimize a mismatch between current in the current-fed inductor and current in the leakage inductance of the transformer when commutation takes place, significantly reducing the power rating for a voltage clamping snubber and enabling use of a simple passive clamped snubber. To minimize the mismatch, the method and control scheme utilizes the resonant tank and freewheeling path in the existing full bridge inverter at the voltage-fed side to preset the current in the leakage inductance of the transformer in a resonant manner. Zero-voltage-switching is also achieved for all the switches at the voltage-fed side inverter in boost mode operation. The proposed soft-commutating method is verified through boost mode operation of a 3-kW bidirectional isolated full bridge dc/dc converter developed for fuel cell electric vehicle applications. The tested result verified the isolated boost converter can operate at an input voltage of 8.5–15V and an output voltage of 250–420V with a peak efficiency of 93% and an average efficiency of 88% at 55-kHz switching frequency with 72$^circ$C automotive coolant.