通信电源技术的创新与发展

作为通信系统的“心脏”，通信电源在通信局(站)中具有无可比拟的重要地位。通信电源的种类很多，不仅包含48V直流组合通信电源系统，而且还包括DC／DC二次模块电源、在线式逆变器等。     

设计通信电源系统时电源拓扑的选择

通信基础设施的设备使用多种电源系统部件。例如在前端馈电网有负载均流和(N 1)冗余的功率因数校正(PFC)AC／DC电源；在后端有高效率DC／DC变换器模块和负载端变换器。本文评论了若干通信电源设计的要求，考虑其成本、性能和标准，还讨论了许多新的分布式电源结构和最适用的变换器拓扑及PWM控制器。     

电源

自动选择USB或AC插座的充电器；高性能电源供应芯片；用于Opteron处理器的插入式电源；医疗及本安领域专用DC／DC模块；双输出DC／DC转换器。     

深圳市源仪电子有限公司T6000开关电源自动测试系统

适用于AC／DC及DC／DC电源转换器的测试应用，开放式系统平台、可自行编辑测试程序、平行式系统架构、测试速度快、提供报表设计、统计分析功能、for Windows的操作界面、最多扩充至12路输出25项标准测试功能、41个量测参数模块化结构容易维修，适用于研发、生产及品检等。     

高效率五通道DSC专用DC／DC转换器——只须单电源输入就可以产生五个不同的电压输出

APS1004是专为数码相机设计的电源管理芯片，同时也可以为其他手持设备提供电源。APS1004只须单电源输入就可以产生五个不同的电压输出，集成的五个通道包括电流模式升压型DC／DC转换器、电流模式降压型DC／DC转换器、三个辅助电压模式升压型脉宽调制（PWM）控制器，集成了软启动、过载保护和启动结束指示（SDOK）等功能。     

电源

电池备份．安全控制器DS3600,可提供20A电流的DC／DC控制器LTC3822,集成数字电源监视器的热插拔控制器,集成低噪声LDO的应用微处理器用电源单元,宽压输入隔离稳压器VFB—YMD-5W,传导升压型DC／DC转换器,5～18V输入的高效率大功率LED驱动芯片PT4105.[编者按]     

电源

800mA、同步降压-升压型DC／DC转换器;用在汽车系统中的双路输出同步DC／DC控制器;高效率7W降压式LED驱动器;用于汽车TFT-LCD的单升压稳压器;适合各种电源应用的交流电流传感器     

电源技术

高效无感应DC／DC升压转换器；3U 10／15kW高密度可绾程电源；开关频率为2．25MHz的低功耗DC／DC转换器；新一代高效开关式三端稳压器；高效率防纂改电表电源设计方案；提供9个电流源的LED驱动器；     

Microchip推崇用于电源控制的16位数字信号控制器

大功率和复杂度较高电源的价格正逐渐走高，而采用数字控制可显著降低成本。来自Darnell Group的统计数字显示，2005年全球功率大于100W的AC／DC和DC／DC电源产品销售额约为138．33亿美元，占所有AC／DC和DC／DC电源产品销售额的一半以上，传统的模拟控制方式已经难以满足这些越来越复杂的大功率电源系统要求。所以，多家IC厂商也已经把重点放在了数字化的电源控制IC上。     

电源

用于便携多媒体系统的单片电源管理器件;2MHz．600mA小型DC／DC转换器;便携式电子设备用电池充电管理IC;连续输出功率200W的小型CompactPCI AC电源;降压式隔离DC／DC解决方案。[编者按]     

Power-aware operating systems for interactive systems

Many portable systems deploy operating systems (OS) to support versatile functionality and to manage resources, including power. This paper presents a new approach for using OS to reduce the power consumption of I/O devices in interactive systems. Low-power OS observes the relationship between hardware devices and processes. The OS kernel estimates the utilization of a device from each process. If a device is not used by any running process, the OS puts it into a low-power state. This paper also explains how scheduling can facilitate power management. When processes are properly scheduled, power reduction can be achieved without degrading performance. We implemented a prototype on Linux to control two devices; experimental results showed nearly 70% power saving on a network card and a hard disk drive     

Hybrid systems modeling for power systems

In this work a framework for modeling power systems using hybrid input/output automata (HIOA) is proposed. The system is assumed to consist of several distinct components. Some of them drive the continuous dynamics while others exhibit event-driven discrete dynamics. Such behavior is characterized by interactions between continuous dynamics and discrete events. Therefore the power systems are an important example of hybrid systems. This hybrid modeling process is applied to a simple power system.     

Re-evaluating systems engineering concepts using systems thinking

Humans (individually, on teams, and in organizations) can follow simple processes to increase their probability of success. Many authors, both technical and nontechnical, have described processes for doing various things like designing a system, attaining business excellence, and solving personal and professional problems. The amazing similarities in these diverse processes suggest that there is a general process that might be closely related to human thinking. This general process was abstracted into the SIMILAR Process. This paper shows how the SIMILAR Process was used to help redescribe the requirements discovery process and system design process     

Indirect closed-loop systems identification of distributed systems

In many cases it is impossible to remove the feedback during systems identification as it will make the system unstable. This paper presents an identification method for spatially interconnected distributed systems with identical subsystems operating in closed-loop feedback control. The proposed method takes into consideration the boundary conditions. The approach provides parameters estimate with minimum bias for unstable plant models when there is additive colored noise in output data. This yields consistent parameters estimate and, compared with other techniques to identify such systems under similar situations, takes far less time. The method is illustrated for two-dimensional systems (one for time and one for space), but is equally applicable for systems having more dimensions in space. The proposed technique is for general two-dimensional systems which may be causal, semi-causal (spatially interconnected systems) or non-causal. The effectiveness of the approach is demonstrated with a simulation example.     

MC DS/SFH-CDMA systems for overlay systems

We introduce the slow frequency hopping (SFH) technique to the multicarrier (MC) code-division multiple-access (CDMA) systems for overlay situations. Using lower chip rate, which results in a narrower spectrum for each carrier and hopping the signal in frequency, the MC direct sequence (DS)/SFH system achieves better performance than the MC DS CDMA system in most cases, especially when the bandwidth of the narrowband interference (NBI) is narrower than one subchannel. It also exhibits a stable performance against the variations of the NBI location and bandwidth. When there is no NBI, the two systems perform approximately the same. The evaluation is performed over a frequency selective Rayleigh fading channel, with both Gaussian approximation and Monte Carlo simulation     

Application of expert systems to systems reliability evaluation

An expert system for diagnosing rough ride problems in heavy trucks has been developed and can be used on a personal computer. The system operates on two levels of knowledge data base: shallow — acquired from truck service personnel and causal obtained from a multiprobe vibration analysis system (MVAS) through a preprocessing neural network. The justification for selecting neural networks is presented as are virtues and drawbacks of the developed system.     

Lithotripter systems

Lithotripsy in its various forms has revolutionalized the treatment of kidney and ureter stones. In extracorporeal lithotrips, pulsed acoustic shock waves are generated outside the body and focused via a coupling medium to the concrement. The location of the focus is controlled by fluoroscopy of ultrasound imaging. Starting from simplified models, two methods for generating shock wave pulses are described: (a) point-like supersonic emitters; and (b) two-dimensional emitters of finite amplitude waves. The principles and performance of a spark-gap emitter with a focusing ellipsoid, an electromagnetic acoustic source with a focusing lens, and a spherical concave piezoceramic source are described and discussed. Commercial lithotripter systems and their components for coupling, imaging, patient handling, and triggering are described and their performance is discussed     

Microelectromechanical systems

The evolution and maturity of microelectromechanical systems (MEMS) in the coming years will be driven less by captive fabrication facilities and process development and more by innovative, aggressive electromechanical systems design. MEMS is poised to take full advantage of advances in information technology and couple them to advances in other disciplines to drive a fundamentally new approach to electromechanical system design and fabrication. By merging sensing and actuation with computation, MEMS will not only invest existing systems with enhanced capabilities and reliability but also will make possible radically new devices and systems designs that will exploit the miniaturization, multiplicity, and microelectronics of MEMS. For the first time, approaches akin to VLSI electronics can be taken to usher in an equally exciting and productive era of VLSI electromechanics     

Microelectromechanical systems

The microfabrication techniques used to develop high-performance closed-loop-controlled microelectromechanical systems (MEMS) are discussed. A generalized MEMS could consist of mechanical components, sensors, actuators, and electronics, all integrated in the same environment. Bulk and surface micromachining, substrate bonding, and electroforming in conjunction with X-ray lithography, all integral components of silicon micromachining, are described. The development of a materials base for MEMS and a variety of physical phenomena for microactuator applications that have recently been demonstrated are reviewed. The applications and future trends of MEMS technologies are discussed