带隔离变压器半桥电路的仿真研究

研究了隔离型半桥变换器,首先阐述其工作原理,并且给出了其在MATLAB/Simulink中的仿真模型和仿真结果,仿真结果与理论分析完全一致。而且通过仿真分析得出带隔离变压器的半桥电路可以实现直流变直流的目的,相对于直流斩波电路,其更不容易发生变压器的偏磁和直流磁饱和。     

一种新颖的软开关半桥变换器

本文提出了一种新颖的软开关半桥变换器,首先介绍了变换器的电路结构,电路工作在谐振状态,通过脉冲频率调制方法调控输出电压和输出功率,并通过时序和电路拓扑分析了变换器的基本原理,最后给出了原理样机的实验波形.     

基于船用半桥LLC谐振变换电路的MOS驱动设计

针对船用开关电源低电压、大电流输出、高效率、电气隔离等需求,采用半桥LLC谐振变换电路方案作为最后级输出进行研究。分析电路中所用MOS管的工作原理和开断过程,简单介绍半桥LLC谐振变换器的工作原理,并给出该变换器的典型驱动方案;发现串扰现象后,给出3种带负压驱动的驱动方案,并分析3种驱动方案的特点,研制出样机并进行试验验证。为开关电源中MOS管的驱动设计提供参考。     

占空比及相位差对开关功放电流纹波影响分析

本文结合H半桥开关功放的工作原理,在两路PWM相位差和占空比均变化的情况下分析了励磁电流纹波变化情况,并通过理论分析给出了两路PWM实现电流纹波最小时的占空比和移相角度所满足的条件。基于开关功放在励磁系统中的应用,构建了一个励磁电流闭环控制系统,Matlab仿真和实验结果均证明了理论分析的正确性,较好地实现了对励磁电流的精确控制,并减小了电流纹波。     

同步发电机励磁电流放大器研究

给出了励磁电流放大器所使用的Buck电路和电压双象限H桥功率主电路的工作原理,并针对后者分析了两路中心对称但占空比不同的PWM实现三电平工作方式(称为对称PWM法),同时提出了采用两路占空比相同但具有一定相位差的PWM控制方法以减小电流纹波(称为移相法)。给出了对称PWM法和移相法两种方式下的电流纹波计算公式,指出半周移相(180°移相)时电流纹波大为减小且几乎不受电源电压影响。利用Matlab对励磁电流放大器进行了仿真,构建了以DSP为控制核心的试验平台,并进行了发电机励磁调节试验。理论分析、数字仿真和试验结果表明,对不同工况下的纹波大小分析正确有效,试验所采用的励磁电流放大器调节性能优良。     

基于H桥的DC-DC变换器理论分析与仿真研究

传统的Buck电路只能实现单极性输出,而对于一些需要双极性输出的场合如直流电机励磁控制器等,则不能满足应用要求。基于H桥的DC-DC变换器在保证与Buck电路相同输出性能的前提下,可以实现双极性输出。分析了基于H桥的DC-DC变换器基本结构,探讨了其基本工作原理,并对其在开环控制下输出性能进行了仿真研究。仿真结果表明基于H桥的DC-DC变换器是可行的。     

三电平中点电压平衡PWM控制策略研究

多电平PWM控制技术是多电平变换器研究的核心内容之一。基于传统两电平PWM技术的研究经验,经过近十几年的发展,多电平PWM控制技术己形成了几类不同的实现方法,同时新的控制方法还在涌现。但一直以来多电平的电压平衡控制就是研究的热点。本文提出了两种基于三电平SVPWM的中点电压平衡控制方法,详细介绍了每种算法的具体操作过程,并给出了改进的思路。     

船舶电力系统中发电机控制负载有效性研究

船舶结构不断发展,其复杂性也越来越高,其中包括负载的复杂性。负载运行的电流、电压及功率都会对发电机产生一定的影响。本文通过研究电子负载的特性,选用双PWM变换器更为合理,通过控制电子元件的占空比大小,对实际负载进行模拟,建立PWM的数学模型,最后通过仿真平台对PWM变换器进行仿真验证,得出发电机对负载控制的有效性。     

一种大功率三电平H桥直流变换器开关函数建模

开关函数的建模方法是研究电力电子变换电路和控制策略的一种有效手段。本文以一种三电平H桥直流变换器为研究对象,基于PWM移相控制策略和开关函数建模方法,搭建了三电平H桥逆变单元的开关函数模型,在MATLAB上开展变换器不同工况下的仿真研究,并与Simlink库自带的H桥逆变器模型仿真结果对比,验证开关函数建模的有效性。     

集成PWM控制器UC1525在开关电源中应用

电力开关变换器出现后,PWM开关技术首先以其电路简单、控制方便而获得了广泛应用。PWM技术是以中断功率流的方式控制占空比来实现功率处理的,其电流及电压波形都是脉动的。本文介绍了集成脉冲宽度调制方式（PWM）控制器（UC1525）的构成与原理,详细分析了以UC1525控制器构成的开关电源的控制电路、驱动电路。     

33rd International Conference on Ocean,Offshore and Arctic Engineering （OMAE2014）

正San Francisco,California,June 8-13,2014.OMAE 2014 is the ideal forum for researchers,engineers,managers,technicians and students from the scientific and industrial communities from around the world to:·meet and present advances in technology and its scientific support;·to exchange ideas and experiences whilst promoting technological progress and its application in industry·to promote international cooperation in ocean,offshore and arctic engineering.In line with the tradition of excellence of previous OMAE conferences,more than 900 technical papers are planned for presentation.Outreach for Engineers Specialty Forum This Specialty Forum is designed for students and professionals who may not be familiar with the Ocean and Offshore industry,as well as those who have just recently specialized in this field.     

Errata

正In the paper"Influence of Fouling Assemblage on the Corrosion Behaviour of Mild Steel in the Coastal Waters of The Gulf of Mannar,India"in Vol.12,No.4,Page:509,References were lost,and the two authors’biographies were identical.The correct text is shown below.We apologize to the authors and our readers for any inconvenience caused by the errors.     

Journal of Marine Science and Application 2014 Sum. Contents

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第34届海洋、离岸及极地工程国际会议(英文)

正St.John's,Newfoundland,Canada,May 31-June 5,2015 OMAE2015 is the ideal forum for researchers,engineers,managers,technicians and students from the scientific and industrial communities from around the world to: meet and present advances in technology and its scientific support;     

联合作战计划和执行系统

全球指挥控制系统(GCCS)实施当前美国海军网络中心战信息基础设施的联合计划网络。联合作战计划和执行系统(JOPES)支持GCCS实现联合计划。JOPES有两类计划：时间不限的精密预案计划生成作战计划、方案计划或职能计划；时间敏感的危机行动计划生成作战命令或战役方案。前者在和平时期创建的作战计划是后者的计划基础，加速应付危机的能力。     

Recent progress on wave induced loading measurements in warships

Recent measurements of wave induced hull strain and flexure in RN warships are presented together with the derivation of the current design criteria for extreme hull girder bending loads. The history of the development of the shipboard instrumentation used is given and recent developments to improve the quality and ease of analysis of the data are described. An unexpectedly high transverse asymmetry in the longitudinal strains measured in destroyers is shown to be the result of a combination of vertical and lateral bending in oblique seas. Finally recent theoretical comparisons between the loading of Deep-Vee hulls and conventional UK rounded bilge hulls are presented which demonstrate the higher loading experienced by this type of hull form.     

The 11th International Conference on Hydrodynamics (ICHD 2014)

正19–24 October 2014 SingaporeCONFERENCE THEMES The overall aim of the ICHD Conference is to provide a forum for participants from around the world to review,discuss and present the latest developments in the broad discipline of hydrodynamics and fluid mechanics.The first International Conference on Hydrodynamics(ICHD)was initiated in 1994 in Wuxi,China.Since then,9 more ICHD conferences were held subsequently in Hong Kong,Seoul,Yokohama,Tainan,Perth,Ischia,Nantes,Shanghai and St Petersburg.Evidently the ICHD conference has become an important event among academics,researchers,engineers and operators,working in the fields closely related to the science and technology of hydrodynamics.The 11th ICHD will be held in Singapore in 2014.     

第十二届深水操作会议和展览会(英文)

正November 4-6,2014Moody Gardens HotelConvention Center/Galveston,TX The Deepwater Operations Conference and Exhibition is celebrating its 12th anniversary this year.This growing event will continue the tradition of excellence in addressing operational challenges involved in developing deepwater resources.We will return to the Moody Gardens Hotel and Convention Center on November 5-7,2014 in Galveston,Texas.     

Eastbound or westbound ?

In terms of equal sailing distances, where is the inflexion when ships depart from ports in the Asian Continent to New York via Suez and/or Panama？
The answer is China South Port Group （Hong Kong, Shenzhen and Guangzhou）.     

Impact of regulation on the performances of long-distance transport services: A comparison of the different approaches in Sweden and Norway

Despite the many socio-economic similarities between Sweden and Norway, differences in jurisdiction, organisation, cooperation, and financing of long-distance passenger train and coach services have led to the development of four distinctively different ways of serving the markets. This paper describes how the train and coach markets have developed in the two countries, with emphasis on regulatory and industrial structure and a couple of performance variables.Looking at passenger rail, both countries separated infrastructure from operation over a decade ago. However, while Norwegian rail is characterised by an almost monopoly supplier, rail services in Sweden are partly decentralised to the responsibility of county authorities and are widely subjected to competitive tendering. The rest of the network is about to be opened up for on-the-track competition. Swedish Rail (SJ) has spent the last decades consolidating its core business (passenger rail) and sold out its other businesses. In contrast, the Norwegian state rail (NSB) has expanded its business to become a major bus operator and property owner, with extensions also into the Swedish market.The coach industry was more recently deregulated in both countries. The Swedish coach market is dominated by privately owned companies operating services to and from Stockholm. In Norway, state-owned NSB is a major coach operator on medium distance routes, and is also the largest partner of Nor-Way Bussekspress which totally dominates long-distance coach services. Further, the Norwegian coach market is characterised by cross-ownership and cooperation which has enabled an extensive route network which covers most of Norway.We find distinct differences in achievements in the two modes and in the two countries. Swedish rail services have succeeded in winning market shares and in renewing and developing both infrastructure and service levels to a greater extent than the Norwegian model. On the other hand, the Norwegian coach market seems to be more developed and efficient compared to its Swedish counterpart.The paper concludes with a discussion on the possible links between the different approaches and the performance observed, with the aim to stimulate further and more detailed research on some important issues.