双向全桥DC-DC变换器单移相闭环控制研究

针对基于传统单移相控制的双向全桥DC-DC变换器存在效率低的问题,提出了一种基于单移相闭环控制的双向全桥DC-DC变换器设计方案;分析了双向全桥DC-DC变换器稳态特性,详细介绍了基于单移相闭环控制的双向全桥DC-DC变换器的建模实现。仿真与实验结果表明,基于单移相闭环控制的双向全桥DC-DC变换器效率高、损耗小。     

PWM DC-DC开关变换器建模、仿真分析研究

DC-DC开关变换电路是一个时变的、非线性的动态系统，它的分析与设计一直是一个难题。以典型PWM Boost变换器为例进行了三种方法建模，首次将高频网络平均法推广到PWM开关变换器中，并建立了低频模型，对状态空间平均法、推广的高频网络平均法、等效小参量法得到的数学模型以及原电路模型应用MATLAB进行了仿真和渡形对比，定性得出其适用范围，所采用的建模方法可推广应用于其他变换器。     

直流微电网中软开关双向DC/DC变换器的仿真研究

在光伏发电微电网中,直流双向变换器作为储能电池和直流母线之间的纽带,承担着能量管理和平衡的重要作用。提出了一种分立式缓冲型软PWM电路作为直流双向变换器,有效减少了开关损耗并能实现能量的双向流动。进行谐振元件的参数设计,运用状态空间平均法建立小信号模型,设计了补偿控制器以改善系统性能,基于PSIM软件建模与仿真,分析系统不同模式下的运行状态及动态切换过程,结果表明所研究的双向变换器能实现软开关工作。     

两种状态平均法在功率变换器建模的应用比较

以buck变换器为对象,采用广义状态平均法建立功率变换器广义状态空间平均模型,并与状态空间平均法进行对比.用MATLAB软件对两种方法建立的模型进行仿真,仿真结果与用MATLAB/PSB建立的电路精确模型和实际电路输出结果进行比较.得出结论:状态空间平均法适于研究直流分量占主要成分,电路各量变化波动不大的变换器电路.广义状态平均法不仅可以反映电路各量的直流成分,也能反映出其交流成分,对于研究类似谐振变换器或波动较大的变换器电路,非常有效.     

PWM开关电源全桥DC－DC变换器的建模与控制设计

非线性PWM开关电源的建模是设计其闭环控制系统的关键,针对PWM开关电源全桥DC－DC变换器,运用状态空间平均法建立了小信号数学模型。在此基础上设计了电流内环、电压外环双闭环反馈系统。通过Matlab对实例进行分析,验证了双闭环参数选择的合理性。     

一种基于PWM控制方法的开关电容DC-DC变换器

本文介绍了一种新型的开关电容升压DC-DC变换器拓扑结构，并利用状态空间平均法进行了稳态分析，最后用PWM控制方法进行了仿真，仿真结果验证了理论分析的正确性。     

峰值电流控制模式有源箝位正激变换器的小信号模型与设计

电流控制模式的补偿网络比电压控制模式的补偿网络容易调整,但是前者的建模要比后者的建模复杂得多。采用状态空间平均法为峰值电流控制有源箝位正激变换器建立了小信号模型,分析了箝位电路对变换器动态性能的影响,并给出了补偿网络的设计方法。     

磁耦合谐振式无线传能系统输出电压GSSA-MPC控制

针对磁耦合谐振式(MCR)无线传能系统中负载变化引起输出电压实时调节的需求,以全桥LCCL系统为研究对象,提出了一种基于状态方程的模型预测控制器(GGSA-MPC).通过广义状态空间平均法(GSSA)对全桥LCCL系统建立等效电路方程并将原副边电压电流进行傅里叶变换,建立了 MCR系统的动态状态空间模型;为了加快求解速...     

一种准Z-源DC-DC变换器的建模与控制

分析了准Z-源DC-DC变换器在稳态时的工作原理,根据状态空间平均法建立了准Z-源DC-DC网络在电流连续工作模式下(CCM)的交流小信号模型,并对模型进行分析,获得控制至输出的传递函数,实现了输出电压闭环控制。最后建立了实验样机,进行了实验验证。     

非理想Buck变换器的建模及仿真

针对以往开关变换器建模过程中一些理想化假设会引起较大误差的问题,为系统预测的稳定性,以Buck变换器为例,采用状态空间平均法建立在非理想条件下的数学模型,并利用MATLAB软件对模型进行仿真,仿真结果与理想模型和Buck变换器实际电路模型的输出波形进行对比分析,非理想模型的仿真波形和实际电路模型的波形基本一致。结论表明建立的非理想Buck变换器状态空间数学模型具有合理性和可行性,在PWM DC-DC开关变换器的建模分析中考虑寄生参数的实用性更强。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate