实用电源（3）

常用开关电源还需要分离元件、IC、功率开关元件和专用整流二极管等器件。其中如常用开关电源控制IC,它的出现大大简化了开关电源的设计制作程序。本文主要介绍常用开关电源需要的如常用开关电源控制IC、     

DSP数字控制开关电源设计及控制算法研究

为了使开关电源具有体积小、智能化等特点,提出采用DSP数字处理技术和模糊PID控制相结合,设计完成了具有响应快、效率高的智能开关电源。通过与外围EMI滤波电路、光电隔离、保护电路等配合,解决了开关电源对电网的污染,保护开关电源因温度等不确定因素对开关电源造成的损坏。本开关电源控制算法先进,设计合理,具有较强的工程应用参考价值。     

基于Saber的反激式开关电源的仿真研究

反激式开关电源因成本低、外围元器件少、可宽电压范围输入能耗小、支持多组输出而备受欢迎,但因输出电压纹波大而严重影响其工作性能。从反激式开关电源的工作原理出发,采用反激式开关电源输出端增加输出滤波电路的方法,解决反激式开关电源输出电压纹波大的问题。运用Saber仿真软件分别对普通反激式开关电源和增加 输出滤波电路的反激式开关电源进行建模和仿真。试验仿真对比表明,通过该方法可改善反激式开关电源的输出电压纹波,提高了反激式开关电源的工作性能。     

开关电源105℃高纹波系列铝电解电容器

开关电源是当今各类电子设备的主要电源,广泛用于PC机、邮电通讯、程控交换机和各种视听电子设备.开关电源为电子设备小型轻便化作出了不可磨灭的贡献.但是,开关电源产生的噪声和高次谐波对市电(交流供电系统)造成极为严重的污染.开关电源电路亟待变革,已成为近两年的焦点话题.随着开关电源技术的革新,对应用于开关电源领域的滤波铝电解电容器提出了更高的要求:耐高温、低阻抗、耐高脉动电流的冲击和小型化.铝电解电容器规范的变更和性能的提高已成为电子产业界的重要研究课题.     

书讯

开关电源技术李金伴李捷辉李捷明编著定价:35.00元本书共10章,着重从工程实用的角度来阐述开关电源技术。第1章阐述了国内外开关电源的发展动态、开关电源的组成和主要性能要求、技术规范。第2章介绍了开关电源的功率变换电路、整流器分类、构成、负载均分技术、控制与驱动电路     

高频开关电源系统的运行维护措施分析

高频开关电源系统是电力系统中重要的设备,其运行状态对于整个电网供电的连续性和稳定性有着直接的影响,因此必须做好高频开关电源系统的运行维护,积极采取有效措施,提高高频开关电源系统的使用寿命和可靠性,确保电网安全、稳定运行。本文简要介绍了高频开关电源系统,分析了高频开关电源系统的运行维护措施。     

开关电源两种控制模型的比较与分析

在现代电源技术中开关电源占有重要的位置,开关电源一般由取样电路、基准电压、比较放大器、开关脉冲、开关管控制构成,其工作原理是控制开关管导通和关断的时间来调节占空比,得到稳定输出电压的一种电源,随着开关电源技术的发展,使得开关电源技术和种类也有了新的突破。目前,开关电源具有更加节能和电能利用效率高等的特点,已经成为电源领域不可缺少的一种电源方式。     

单片开关电源新校术概述

单片开关电源自20世纪90年代中期问世以来便显示出强大的生命力,它作为一项颇具发展前景和影响力的新产品,引起了国内外电源界的普遍关注。单片开关电源具有高集成度、高性价比、最简外围电路、最佳性能指标等特点,现已成为开发中、小功率开关电源、精密开关电源及开关电源模块的优选集成电路。目前,单片开关电源正朝着短、小、轻、薄、节能、安全的方向发展。本文介绍国际上单片开关电源领域的几项新技术。“绿色节能”型单片开关电源目前,国外许多著名的IC厂家都在大力开发低功耗、节能型单片开关电源集成电路,Philips的TEA1520系列即…     

单片开关电源新技术概述

单片开关电源自20世纪90年代中期问世以来便显示出强大的生命力,它作为一项颇具发展前景和影响力的新产品,引起了国内外电源界的普遍关注.单片开关电源具有高集成度、高性价比、最简外围电路、最佳性能指标等特点,现已成为开发中、小功率开关电源、精密开关电源及开关电源模块的优选集成电路.目前,单片开关电源正朝着短、小、轻、薄、节能、安全的方向发展.本文介绍国际上单片开关电源领域的几项新技术.     

一类封装相同或相似电源管理芯片的识别

开关电源是卫星数字接收机的重要组成部分,也是卫星数字接收机故障率最高的部位。从开关电源的结构来说,数字机的开关电源主要由输入电路、主变换电路、取样稳压电路和输出电路等组成,不同类型开关电源差别最大的则为主变换电路,也常     

Modeling the optical switching of MESFET's considering the externaland internal photovoltaic effects

One of the aspects of the merging of microwave and optical technologies is the use of optical signals to switch electronic circuits in general and microwave circuits in particular (including MMIC). During the last decade, the feasibility of optical switching of MMIC's has been demonstrated. This paper presents a novel model for the optical switching of the MESFET, which is the building block of MMIC's. The model predicts the optical switching performance as a function of the optical signal parameters, the bias level, and the device physics and geometry. The results and conclusions from the theory are verified by measurements. The new model can serve as a design tool for designing an optimal MESFET for optical switching purposes     

A study of the internal device dynamics of punch-through andnonpunch-through IGBTs under zero-current switching

The effective use of power insulated gate bipolar transistors (IGBTs) requires a good understanding of their internal device physics. This understanding is essential for the optimal interaction among the IGBTs, their snubber elements and the power circuit in which the IGBTs operate. As switching frequencies are pushed to higher values, switching loss reduction becomes an essential part of the design and optimization process. Soft switching techniques such as zero-voltage switching (ZVS) and zero-current switching (ZCS) are widely used for this purpose. This study provides an insight into the internal dynamic behavior of IGBTs under zero-current switching. The latter is accomplished through mixed-mode simulation, providing the necessary insight for the improvement of circuit and device performance. In particular, the authors have analyzed the behavior of the negative current in nonpunch-through (NPT) devices after the first zero-current crossing and the effect of the turn-off delay on the tail current. They have also experimentally characterized punch-through (PT) and NPT IGBTs to confirm the insights provided by the mixed-mode simulation     

Pulse generation and processing with GaAs bistable switches

Successful operation of high current drop “bistable switching” from X-band supercritical transferred electron devices is reported. Also the potential use of this type of switches in applications such as pulse generation, amplification, and processing is demonstrated. This class of switches with high switching speed offers exciting prospects in the field of fast pulse processing and logic circuits.     

Advanced internetwork design — today and in the future

This paper highlights the current approach to large-scale internetwork design using today's network layer routeing protocols. It describes how large internetworks can be constructed to provide stability, resilience and scalability, together with a set of best practice design guidelines for those involved in the planning of large data networks, highlighting the key issues to be considered. The paper looks at how new technologies are likely to enhance this design approach, in particular, how the full potential of cell switching can be realised through emerging technologies such as integrated switching and routeing. The paper concludes that the model proposed for large-scale networks based on current routeing protocols and technologies can be enhanced to make optimum use of switched WAN services such as ATM, through the use of newer routeing technologies.     

Performance of DSWC diversity system using suboptimum adaptive switching threshold in independent and correlated nakagami‐m fading channels

The use of dual switched combining (DSWC) diversity reception scheme, for combating the detrimental effects of fading on digital transmissions, is popular due to its simpler implementation. The performance of switched diversity strategy is dependent on the selection of the switching threshold. But, for the analysis and design of the DSWC diversity system, the closed form analytical solution for optimum adaptive switching threshold is not possible for most of the modulation schemes in correlated fading environment. This letter presents an approximate, but simple and closed form, generic expression for adaptive switching threshold, called in this case as suboptimum adaptive switching threshold, in independent and correlated Nakagami‐m fading channels for a wide range of binary and M‐ary modulation schemes. It is shown that the average symbol error rate (ASER) performance obtained using this suboptimum adaptive switching threshold is almost same as obtained using optimum adaptive switching threshold. Copyright © 2005 John Wiley & Sons, Ltd.     

On the address inputs of a multiplexer

The digital multiplexer is useful in implementing switching functions. The implementation of some switching functions, however, requires an extra inverter. Sometimes, the need for an inverter can be obviated by suitably selecting the address inputs of the multiplexer. In an earlier paper, we presented a systematic method for selecting the address inputs of the multiplexer. This paper presents another simple systematic method for the same purpose. Unlike the previous method which makes use of a table, the method presented here makes use of a simple theorem.     

Characterization of hard- and soft-switching performance of high-voltage Si and 4H-SiC PiN diodes

This paper presents a study of the performance of high-voltage Si and 4H-SiC diodes in a DC-DC buck converter. Device operation in both hard- and zero-voltage switching conditions is presented with the help of measurements and two-dimensional (2-D) mixed device-circuit simulations. Experimental results show that SiC PiN diodes have a strong potential for use in high-speed high-voltage power electronics applications operating at high temperature. A combination of low excess carrier concentration and low carrier lifetime results in superior switching performance of the 4H-SiC diode over ultrafast Si diodes. Soft switching is shown to minimize the switching loss and allow operation at higher switching frequencies using Si diodes. The power loss of 4H-SiC diodes is dominated by conduction loss. Consequently, soft-switching techniques result in a marginal reduction in power loss. However, the low overall power loss implies that SiC diodes can be used at very high switching frequencies even in hard-switching configurations.     

Physical modeling of the step recovery diode for pulse and harmonic generation circuits

A simple charge-controlled switching model describes most fundamental aspects of the step recovery diode. However, it is shown that switching speed and the associated loss are related to the width of the i layer and to the doping level. A switching model appropriate for general computer use is given, and examples of its application are shown in pulse and harmonic generator circuits.     

The new possibilities of telephone switching

Switching system architectures have evolved to be responsive to the needs of the user. Their design has been constrained by the existing environment which treats terminals, transmission channels, and switching entities as separate "black boxes." Telephone switching circuits have used relatively expensive discrete components, and hence, system designers used common control techniques to minimize the system cost. This was done by providing the circuits in common whenever this was possible. Such common circuits were associated with a switched path for the period of time for which the functions of the circuit were required. This was followed by "one at a time" operation and by the use of stored program controls. The advent of low-cost electronic circuit components has resulted in the application of digital techniques to switching systems. For the first time, the combination of switching and transmission is possible. This is the near-term objective. The long-term objective, made possible by forecasts of low-cost memory and electronic gate circuits, is the combination of switching, transmission, and the terminals. This will result in much more complex terminals.     

On the synergy between electrical and photonic switching

This article focuses on the values of electrical switching vs. photonic switching in the context of telecom transport networks. In particular, we show that the requirement of providing agility at the optical layer in the face of traffic forecast uncertainties is served better through photonic switching. On the other hand, some of the network-level functions, such as fast protection, subwavelength aggregation, and flexible client connectivity, require electrical switching. We further argue that additional values are achieved with hybrid photonic and electrical switching, which do not exist when either of these options is used in isolation.