电力电子技术英文版 Chapter09
电力电子技术介绍英语作文
电力电子技术介绍英语作文As you know, information plays an important role in our modern society. Some people say that we are an information society. I agree with him.In fact, as a member of modern society, information is growing at a faster and faster rate. I fully realize the importance of information to my life. It affects almost every aspect of my life, such as How to obtain and process information seems to me the most important.The first way to get information is to go to the library. Our library is too big. It covers a wide range of subjects.All kinds of information can be obtained in it. Information about society, economy, politics and science will give you a new thinking. Of course, library is not the only source of information I can learn a lot of information through other ways.Even if I chat with friends, I can get a lot of useful information, but the information is so huge that we don't have enough energy and time to deal with it deeply. In addition, some information may not be true, and how to choose information isalso important to me. I believe that only three out of ten people can get accurate information and eliminate the false parts.Our goal should be to make full use of information in my present life. After I enter the society a few years later, I will try my best to use it mainly for learning. Information may become more and more important.中文翻译：正如你所知，信息在我们的现代社会中扮演着重要的角色有人说我们是一个信息社会我同意他的观点事实上，作为现代社会的一员，信息正以越来越快的速度增长，我完全意识到信息对我生活的重要性，它几乎影响到我生活的方方面面生活中如何获取和处理信息对我来说似乎是最重要的，获取信息的第一条途径就是去图书馆我们的图书馆太大了，它涵盖了广泛的学科，各种各样的信息都可以在其中得到，关于社会、经济、政治和科学的信息会给你一个全新的思维当然，图书馆并不是唯一的信息来源，我可以通过其他方式学到很多信息，即使和朋友聊天，我也能得到很多有用的信息，但是信息是如此巨大，以至于我们没有足够的精力和时间去深入地处理它。
学术英语写作与研究方法(第二版)PPT Chapter 09 Entering an Academi
Chapter Nine Entering an Academic Conversation
CONTENTS
9.1 Entering an academic conversation 9.2 What “they say”: The literature review 9.3 What “I say”: Raising and addressing a question 9.4 Identifying the structural “moves” in a scholarly
Listening, of course, is important, and it is a good thing that you are, most likely, an accomplished listener. But you are getting ready to step into the “conversation” and say something new about the topic.
M.A.K.Halliday
Confucius
Socrates
If you are doing a study in applied linguistics, imagine that some of the most famous linguists of all time are sitting in the room, possibly including Noam Chomsky.
Chapter09_new
19
链式实现
链式实现
以结点的概念为基础。 结点（Node） 一个结点由两部分数据构成：
– 存入列表的项目 (item) – 指向列表中的下一个结点的指针 (next)
20
链式实现
图 9.4 一个链式列表的 Figure 9.4 Anatomy of a linked list 结构图
21
链式实现
36
快速排序
基本思想：通过一趟排序将待排记录分割成 独立的两部分，其中一部分记录的关键字均 比另一部分的小，则可对这两部分记录继续 进行排序，以达到整个序列有序。
37
快速排序
图 9.12 用快速排序算法对一个列 表排序 38
It is easier to sort a smaller number of items: Sort A…F, G…L, M…R, and S…Z and A…Z is sorted
图 9.5 无序链式列表
22
链式实现
图 9.6 有序链式列表
23
链式实现
操作的实现?
Add item Remove item Get next item more items
24
链式实现
图 9.7 把info为 67的结点存入current之后
25
链式实现
图 9.8 删除结点next(current)
1.从具体问题抽象出一个适当的数学模型。（分析问题） 2.设计一个解此数学模型的算法。
3.编写出程序。
3
数据结构
问题：非数值计算问题无法用数学方程加以 描述。
图书馆书目检索系统自动化问题？（线性的） 计算机和人对弈问题？（树） 多叉路口交通灯管理问题？（图）
纽曼社会研究方法英文版PPTChapter 09 - Experimental Research
Random Assignment
Copyright ©2011 by Pearson Education, Inc. All rights reserved.
Random Sampling
Copyright ©2011 by Pearson Education, Inc. All rights reserved.
Experimental Design Logic
Steps in an Experiment
• Hypothesis • Choose a design • Design experiment
– How to introduce IV – How to measure DV
• Locate subjects • Randomly assign subjects • Gather pretest data • Run experiment
How to Random Assign
Copyright ©2011 by Pearson Education, Inc. All rights reserved.
Matching vs. Random Assignment
• Matching • Random Assignment
Copyright ©2011 by Pearson Education, Inc. All rights reserved.
– Experimental realism
Copyright ©2011 by Pearson Education, Inc. All rights reserved.
External Validity
Copyright ©2011 by Pearson Education, Inc. All rights reserved.
电力电子技术双语课件第1章
II.
The history
Application of fast-switching Invention of fully-controlled Thyristor semiconductor devices GTO GTR Mercury arc rectifier Power MOSFET Power diode Vacuum-tube rectifier Thyristor Thyristor Thyratron (microprocessor)
Other applications
14
Industrial applications
Motor drives
Electrolysis
Electroplating
Induction heating
Power
Welding Arc furnaces and ovens Lighting
15
Transportation applications
13
III. Applications
Industrial Transportation Utility systems
Power supplies for all kinds of electronic equipment
Power
Residential and home appliances
Space technology
Power electronics: to process electric power
Other classifications of electronics
Power
Electronics
Vacuum electronics: using vacuum devices, e.g, vacuum tubes devices Solid (Solid state) electronics: using solid state devices, e.g, semiconductor devices Physical electronics: physics,material,fabrication, and manufacturing of electronic devices Applied electronics: application of electronic devices to various areas 9
电气考研：电力电子课程英文版
The concept of power electronic devices
Power electronic devices：
are the electronic devices that can be directly used in the power processing circuits to convert or control electric power.
electronic devices
3
1.1 An introductory overview of power electronic devices
The concept and features Configuration of systems using power
electronic devices Classifications Major topics
A power electronic device usually has a third terminal —— control terminal to control the states of the device.
A power electronic device must have at least two terminals to allow power circuit current flow through.
12
Major topics for each device
Appearance, structure, and symbol Physics of operation
Characteristics
Static characteristics Switching characteristics
“电力电子技术”双语教学的实践与分析
章为绪论 （ 原文 版第一、二章 ） 、第二章为 电力电子器件 （ 原
有核心课程性 质的较为重要 的专业基础课 。本课程工程实践性 文版第二十～第二十五章 ） 、第 三章 为不可控 整流 电路 （ 原文版 较强 ，其应用 已渗透 到工业生产和社会生活的各 个领域。在本 第五章 ） 、第 四章为可控整流电路及其逆变工作状 态 （ 原文版第
真 的教 学 模 式引入 课 堂 教 学 。
考试形式采用闭卷 考试，中英文题 目的分 值各 占 ５ ％，采 ０
出卷形式和考试方式。
用同场 Ａ、Ｂ卷分 卷考试 ，这是在本次双语教学 中首次尝试的 析与试 验比较相 结合。学 生的作业和实验报告 也是围绕这 两点 二 教学 内容的组织
首先是教材的选择。我们选择的教材是 ｛ ｏ ｒ Ｅｅ ｔｏ ｉｓ （ ｗｅ ｌｃｒｎｃ Ｐ
课程 中使 用双语教学 ，是提高教学量、更好地培养高水平工 六章） 、第五章 为斩波电路 （ 原文版第七章） 、第六章为逆 变电 程技术人 才的一个有 效手段 。
一
路 （ 原文版第八章） 、第七章为电力电子技术的控制技术 （ 原文 版第九章） ，第八章为电力电子技术的应用 （ 原文版第十章） 。 此外，为提高课程教学的实践性和配合 学校提 出的研 究性
教 学 要求 ，在每 章 教 学 结 束后 ，都 提 出了相 关 的 设 计 性 小 课题 ，
．
本课程双语教学体系的设计
为适应本课程双语教学 的特殊性 ，我们在其教学体系上作
了较 大 调 整 。
首先是重新编 写了教学大纲。在 编写教学 大纲时，充分考 作为课后练习或在课程设计环节中研究 。 虑了所选教材的具体 内容。例如，原文版教材中采用了较多的仿 真波 形和 实际波形，我们就在教学 大纲中提出仿真 软件 的学 习 三．教学过程的实施
Chapter_09 经济发展 economic growth. weil 课件
Chapter 9THE CUTTING EDGE OF TECHNOLOGY Marco SavioliThe cutting edge of technology«Cutting edge technology»: new techniques that are just moving out of development and into production. Cutting edge technologies hold great promise for higher productivity, although they are not guaranteed to work (eg quantum computing, gene therapy, …)With time, technologies that are at the cutting edge become commonplace or even obsoleteThe era of rapid technological progress dates back only250 years in the most advanced countries. Before this period, technological advance was slow and sporadic. Even today, waves of progress alternate with periods of slack technoligical changethe 18th centuryFocus on Europe: not only it is the area for which the best data are available but also it had become the world’stechnology leader by 1700Growth accounting for such an early period poses problems. The avalable data are quite sparse. Land (X) played an important role as an input thenY=AXβL1−βy=A XLβ→LADS→y=A+βX−βLConsidering a geographical area of constant size: X=0A=y+βLthe 18th centuryTo calculate the growth rate of productivity A we need data on the growth rates of income per capita and the size of the populationIn preindustrial economies the share of national income paid to land owners was one-third: β=13Table 9.1 Growth Accounting for Europe,A.D. 500–1700500-1500: the Malthusian model of population fit Europe well1500-1700: growth rate of productivity was five times as high but extremely slow in comparison to what we see in the world todayThe most significant turning point in the history of technological progress, generally dated1760-1830 in Britain, spreading somewhat later to continental Europe and North AmericaBusiness began to mechanize production in ways that would allow the transfer of tasks performed by skilled artisans to machines working faster and tirelesslyTextiles: innovations in the manufacture of textiles, particularly cotton; a wave of new inventions in spinning, weaving, and printing fabric; as a consequence, the use of underwear became common for the first timeEnergy: wind, water, animals, and human muscle had been the only sources of mechanical energy for millenia. The steam engine, in which burning fuel produced steam to drive a piston, represented a revolutionary break with the past. Using the steam engine tapped the vast chemical energy contained in coal deposits as a source of mechanical energyMetallurgy: the widespread replacement of wood coal as a source of fuel in iron smelting, as well as several important technical innovations, drammatically drove down the cost of iron production. By 1825 England, with 2% of the world population, was producing half of the world’s ironFigure 9.1 British Iron Production, 1600–1870Figure 9.2 British Output and Productivity Growth, 1760–1913The industrial revolutionDespite the technological upheavals, the pace of economic growth was quite slow by modern standardsGrowth in productivity and output did not stop or even slow down with the end of the industrial revolution in1830: «second industrial revolution», 1860-1900, withinnovations in industries such as chemicals, electricity, and steelThe technologies introduced during the industrial revolution were revolutionary, but their impact was small because they were initially confined to a few industriesThe industrial revolution was a beginning. The pattern of continual growth that began then was indeed revolutionary in contrast to what had come beforeFigure 9.3 U.S. Output and Productivity Growth, 1870–2007Technological progress since the industrial revolution1890-1971: period of high growth of US total factor productivity.During this period, there were important changes like electriclights, refrigeration, air conditioning, telephone, automobile, air travel, radio, television, and indoor plumbing. Technologiesinvented previously but only then diffusion of themDramatic reduction in the growth rate of productivity starting in the early1970s, throughout all the developed worldEfficiency fell in this period: large increases in the price of oil in 1973 and 1979 threw the industrial economies into chaosRecessions, one in 1974 and another in 1981-1983, left a significant fraction of the capital stock sitting idleStarting in the mid-1990s, change in the trend. Maybe a third industrial revolution centered on computing and ICTThe technology production functionTechnological progress does not occur spontaneously but rather as a result of deliberate effortTechnology production function: the output is new technologies and the inputs are labor and human capital of researchers, along with the capital they useThe best evidence regarding the output of the technology production function is the growth rate of productivity:productivity growth does not give much evidence of along-term rise in the rate of technological progressThe input to technological progress has grown substantially over time, whereas the growth rate of technology has notWe used a simple form of the technology p.f.: A=L AμGeneral-purpose technologiesGeneral-purpose technologies are momentous technological innovations that change the entire nature of the economy. They change the mode of production in many different sectors of the economy and trigger a chain of reaction of complementary inventions that take advantage of the new technological paradigm. Therefore, the period of growth resulting from a single general-purpose technology can go on for several decadesRecent g-p technology:semiconductor(transistor and integrated circuit), basis of modern computersScience and technologyScience: understanding about how the world works, about physical and biological processesTechnology: knowledge of production techniquesFor most of the human history, technological advance was largely unrelated to any scientific understanding of the rules by which the universe operated. Productive technologies were discovered by trial and error. Technological advance opened the way for greaterscientific understanding, by posing puzzles to solve and givingscientists tools for experimentsBut without scientific understanding no technologies of the second industrial revolution(1860-1900): steel, chemicals, electricityIn the 20th century, technological breakthroughs likesemiconductor, laser, and nucelar power on scientific undersanding of how the universe functions. However, advances in physics depend on new pieces of technlogies(particle accelerators)of technological progressIsaac Newton: «If I have seen farther than others, it is because I have stood on the shoulders of giants»Scientific knowledge is cumulative: researchers today begin their investigations where those who came beforethem left off. Same incremental nature for the productive technologies that interest economistsCumulative nature of technological progress+ Researchers today have a larger base of knowledgeon which to build and a larger set of tools-Researcher today might have more difficulty thinkingof new technologies simply because the easiestdiscoveries have already been made: fishing out effect.Further, it takes more effort today for a researcher tolearn everything required to work at the cutting edgeof technological progressA=L Aμdoes not depend on A: + -cancel outBut this assumption is probably not justified. Data show that the input into R&D has risen dramatically, but the pace of technological progress has remained constant or even fallen. Therefore, -winsMany of the key breaktroughs of the 18th and 19th centuries resulted from the labors of lone scientists or inventors, often working in their spare time. By contrast, by the late 20th century, almost all advances were made by large and well-funded research teamstechnology productionA=L Aμmeans that if we doubled the number of researchers doing R&D (and all other inputs into R&D as well), we would double the rate of technological progressThe technology production function should be however characterized by decreasing returns to scaleOnce a piece of knowledge has been created, it can be costlessly shared among any number of people→nonrivalry: if several people are all trying to create the same piece of knowledge, then the efforts of most of them will ultimately be wasted. After the first person has created the knowledge and shared it, the efforts of all of the others who were trying to create that piece of knowledge willhave been in vaintechnology productionParallel efforts to solve a particular technological problem often result in «patent races» in which the winner gets a patent and the loser(s) get nothingWhen R&D is conducted on parallel tracks, the researchers often create parallel solutions to the same problem and develop parallel standardsThe more effort that is devoted to R&D, the more likely is this duplication of effort. Therefore, devoting more effort to R&D will not generate a proportional increase in the pace of technological progressAn improved version of the technology production functionA=L Aμhas two potential problems: negative effect of the level of technology on the growth rate of technology(fishing out effect), decreasing returns to scaleTo incorporate the fishing out effect:A=L AμA−ϕ,0<ϕ<1To incorporate decreasing returns to scale:A=L Aλμ,0<λ<1An improved version of the technology production functionA =1μL AλA−ϕIf the growth rate of technology is constant, A=k, kμ=L AλA−ϕ→LADS→0=λL A−ϕAA=λϕL AWe can use this equation, along with data on technological progress and growth of the R&D labor force, to learn about the parametersλand ϕtechnological progressSummarizing the two modifications to our technological production functionAs the level of technology rises, finding newdiscoveries becomes ever harderAs the effort devoted to R&D increases, theeffectiveness of each new researcher fallsBoth imply that ever-increasing input into R&D will be required to maintain the current speed of technological progressIs such an increase possible, or will technological progress inevitably slow down?technological progressPossible sources of growth in labor devoted to R&D The overall labor force could grow: in the last half-century there has been growth in population andincrease in women labor force participation; developedcountries no more labor force growthThe fraction of the labor force engaged in R&D couldgrow: it has been very important but it is impossible torise above100%New members coud be added to the set of countriesdoing cutting-edge research: today, this countriesaccount for only14% of world populationPlenty of room to expand the number of researchers, but in the very long run, assuming that the world’s population stabilizes, the growth rate of technology will slow downTable 9.2 U.S. Patents and Patents per Million Residents, 2010We can identify cutting edge bylooking at dataon patentsrelative to acountry’spopulation Pharmaceutical s: patenting isimportant;food andtextiles:secrecy andlead time aremore importantCountries thatspecialize intheseindustries havea low rate ofpatentingDifferential technological progressThe pace of technological progress is radically different in various sectors of the economy. Some industries, such ascommunications, have changed beyond recognition over the past century. Other completely new industries have been created,such as television and air travel. In other sectors productiontoday looks the same as it did a century ago (barbers andteachers use the same tools)Changes in the relative prices of goods reflect differential changes in productive technology. Goods where there has been a lot of productivity growht now have become cheapWhen technological progress occurs in a larger sector, the average rate of technological progress rises moreIf fraction of income spent on sectors with rapid technological growth rises, the overall growth rate of technology will also riseTechnological progress in the real world: goods vs servicesProduction methods for goods have been one of the most technologically dynamic areas in the economyThe production processes for many of the services we consume have changed little over the last centuryAs a result, a change has occurred in the relative prices of goods and servicesThe cost disease(William Baumol): shifting of expenditures into services, where productivity growth is slow and relative costs rise, for instance educationTeachers are being replaced with internet technology, music from actual musician to free reproductionFigure 9.5 Price of Computers, 1982–2010ICT isthemostdynamic partof theeconomy today Moreandbettercomputersbutpricesarefalling,spendingstaysconstantFigure 9.6 Investment in Computers as a Percentage of GDP, 1982–2009。
电力电子技术双语课件第1-2章
Power
Two types of electric power DC(Direct Current)
AC (Alternating Current)
Changeable properties in conversion
Magnitude
Frequency, magnitude, number of phases
10
Relation with multiple disciplines
Power
Circuit theory
Electric machines
Systems & Control theory
Signal processing
Power electronics
Simulation & computing
14
Power
Industrial applications
Motor drives Electrolysis Electroplating Induction heating Welding Arc furnaces and ovens Lighting
15
Power
Transportation applications
Reference
(commanding)
Control is invariably required.
Power converter along with its controller including the
corresponding measurement and interface circuits, is
Power electronics and information electronics make two poles of modern technology and human society—— information electronics is the brain,and power electronics is the muscle.
电力电子技术双语课件第3-4章
VT
VT
Power
L
L
u2
u2
R
R
a)
b)
L did dt
Rid
2U2 sin t
(3-2)
ωt = ，id= 0
id
2U 2
sin(
R (t )
)e L
Z
2U2 sin(t ) Z
(3-3)
6
Single-phase half-wave controlled
rectifier with freewheeling diode
2 d
d
(t
)
2 Id
(3-7)
O uVT
t
g)
IVDR
1 2
2
Id2d (t)
2
Id
(3-8)
O
t
Maximum forward voltage, maximum reverse voltage
Disadvantages:
– Only single pulse in one line cycle
The time-domain behavior of a power electronic
circuit is actually the combination of consecutive
transients of the different linear circuits when the
power semiconductor devices are in different states.
VT3
VT1
Power
T i2 a
u1
u2
b
L ud
外文翻译—电力电子技术（英文+译文）
1 Power Electronic ConceptsPower electronics is a rapidly developing technology. Components are tting higher current and voltage ratings, the power losses decrease and the devices become more reliable. The devices are also very easy tocontrol with a mega scale power amplification. The prices are still going down pr. kVA and power converters are becoming attractive as a mean to improve the performance of a wind turbine. This chapter will discuss the standard power converter topologies from the simplest converters for starting up the turbine to advanced power converter topologies, where the whole power is flowing through the converter. Further, different park solutions using power electronics arealso discussed.1.1 Criteria for concept evaluationThe most common topologies are selected and discussed in respect to advantages and drawbacks. Very advanced power converters, where many extra devices are necessary in order to get a proper operation, are omitted.1.2 Power convertersMany different power converters can be used in wind turbine applications. In the case of using an induction generator, the power converter has to convert from a fixed voltage and frequency to a variable voltage and frequency. This may be implemented in many different ways, as it will be seen in the next section. Other generator types can demand other complex protection. However, the most used topology so far is a soft-starter, which is used during start up in order to limit the in-rush current and thereby reduce the disturbances to the grid.1.2.1 Soft starterThe soft starter is a power converter, which has been introduced to fixedspeed wind turbines to reduce the transient current during connection or disconnection of the generator to the grid. When the generator speed exceeds the synchronous speed, the soft-starter is connected. Using firing angle control of the thyristors in the soft starter the generator is smoothly connected to the grid over a predefined number of grid periods. An example of connection diagram for the softstarter with a generator is presented in Figure1.Figure 1. Connection diagram of soft starter with generators.The commutating devices are two thyristors for each phase. These are connected in anti-parallel. The relationship between the firing angle (﹤) and the resulting amplification of the soft starter is non-linear and depends additionally on the power factor of the connected element. In the case of a resistive load, may vary between 0 (full on) and 90 (full off) degrees, in the case of a purely inductive load between 90 (full on) and 180 (full off) degrees. For any power factor between 0 and 90 degrees, w ill be somewhere between the limits sketched in Figure 2.Figure 2. Control characteristic for a fully controlled soft starter.When the generator is completely connected to the grid a contactor (Kbyp) bypass the soft-starter in order to reduce the losses during normal operation. The soft-starter is very cheap and it is a standard converter in many wind turbines.1.2.2 Capacitor bankFor the power factor compensation of the reactive power in the generator, AC capacitor banks are used, as shown in Figure 3. The generators are normally compensated into whole power range. The switching of capacitors is done as a function of the average value of measured reactive power during a certain period.Figure 3. Capacitor bank configuration for power factor compensation ina wind turbine.The capacitor banks are usually mounted in the bottom of the tower or in thenacelle. In order to reduce the current at connection/disconnection of capacitors a coil (L) can be connected in series. The capacitors may be heavy loaded and damaged in the case of over-voltages to the grid and thereby they may increase the maintenance cost.1.2.3 Diode rectifierThe diode rectifier is the most common used topology in power electronic applications. For a three-phase system it consists of six diodes. It is shown in Figure 4.Figure 4. Diode rectifier for three-phase ac/dc conversionThe diode rectifier can only be used in one quadrant, it is simple and it is notpossible to control it. It could be used in some applications with a dc-bus.1.2.4 The back-to-back PWM-VSIThe back-to-back PWM-VSI is a bi-directional power converter consisting of two conventional PWM-VSI. The topology is shown in Figure 5.To achieve full control of the grid current, the DC-link voltage must be boosted to a level higher than the amplitude of the grid line-line voltage. The power flow of the grid side converter is controlled in orderto keep the DC-link voltage constant, while the control of the generator side is set to suit the magnetization demand and the reference speed. The control of the back-to-back PWM-VSI in the wind turbine application is described in several papers (Bogalecka, 1993), (Knowles-Spittle et al., 1998), (Pena et al., 1996), (Yifan & Longya, 1992), (Yifan & Longya, 1995).Figure 5. The back-to-back PWM-VSI converter topology.1.2.4.1 Advantages related to the use of the back-to-back PWM-VSIThe PWM-VSI is the most frequently used three-phase frequency converter. As a consequence of this, the knowledge available in the field is extensive and well established. The literature and the available documentation exceed that for any of the other converters considered in this survey. Furthermore, many manufacturers produce components especially designed for use in this type of converter (e.g., a transistor-pack comprising six bridge coupled transistors and anti paralleled diodes). Due to this, the component costs can be low compared to converters requiring components designed for a niche production.A technical advantage of the PWM-VSI is the capacitor decoupling between the grid inverter and the generator inverter. Besides affording some protection, this decoupling offers separate control of the two inverters, allowing compensation of asymmetry both on the generator side and on the grid side, independently.The inclusion of a boost inductance in the DC-link circuit increases the component count, but a positive effect is that the boost inductance reduces the demands on the performance of the grid side harmonic filter, and offers some protection of the converter against abnormal conditions on the grid.1.2.4.2 Disadvantages of applying the back-to-back PWM-VSIThis section highlights some of the reported disadvantages of the back-to-back PWM-VSI which justify the search for a more suitable alternative converter:In several papers concerning adjustable speed drives, the presence of the DC link capacitor is mentioned as a drawback, since it is heavy and bulky, it increases the costs and maybe of most importance, - it reduces the overall lifetime of the system. (Wen-Song & Ying-Yu, 1998); (Kim & Sul, 1993); (Siyoung Kim et al., 1998).Another important drawback of the back-to-back PWM-VSI is the switching losses. Every commutation in both the grid inverter and the generator inverter between the upper and lower DC-link branch is associated with a hard switching and a natural commutation. Since the back-to-back PWM-VSI consists of two inverters, the switching losses might be even more pronounced. The high switching speed to the grid may also require extra EMI-filters.To prevent high stresses on the generator insulation and to avoid bearing current problems (Salo & Tuusa, 1999), the voltage gradient may have to be limited by applying an output filter.1.2.5 Tandem converterThe tandem converter is quite a new topology and a few papers only have treated it up till now ((Marques & Verdelho, 1998); (Trzynadlowski et al., 1998a); (Trzynadlowski et al., 1998b)). However, the idea behind the converter is similar to those presented in ((Zhang et al., 1998b)), where the PWM-VSI is used as an active harmonic filter to compensate harmonic distortion. The topology of the tandem converter is shown inFigure 6.Figure 6. The tandem converter topology used in an induction generator wind turbine system.The tandem converter consists of a current source converter, CSC, in thefollowing designated the primary converter, and a back-to-back PWM-VSI, designated the secondary converter. Since the tandem converter consists of four controllable inverters, several degrees of freedom exist which enable sinusoidal input and sinusoidal output currents. However, in this context it is believed that the most advantageous control of the inverters is to control the primary converter to operate in square-wave current mode. Here, the switches in the CSC are turned on and off only once per fundamental period of the input- and output current respectively. In square wave current mode, the switches in the primary converter may either be GTO.s, or a series connection of an IGBT and a diode.Unlike the primary converter, the secondary converter has to operateat a high switching frequency, but the switched current is only a small fraction of the total load current. Figure 7 illustrates the current waveform for the primary converter, the secondary converter, is, and the total load current il.In order to achieve full control of the current to/from the back-to-back PWMVSI, the DC-link voltage is boosted to a level above the grid voltage. As mentioned, the control of the tandem converter is treated in only a few papers. However, the independent control of the CSC and the back-to-back PWM-VSI are both well established, (Mutschler & Meinhardt, 1998); (Nikolic & Jeftenic, 1998); (Salo & Tuusa, 1997); (Salo & Tuusa, 1999).Figure 7. Current waveform for the primary converter, ip, the secondary converter, is, and the total load current il.1.2.5.1Advantages in the use of the Tandem ConverterThe investigation of new converter topologies is commonly justifiedby thesearch for higher converter efficiency. Advantages of the tandem converter are the low switching frequency of the primary converter, and the low level of the switched current in the secondary converter. It is stated that the switching losses of a tandem inverter may be reduced by 70%, (Trzynadlowski et al., 1998a) in comparison with those of an equivalent VSI, and even though the conduction losses are higher for the tandem converter, the overall converter efficiency may be increased.Compared to the CSI, the voltage across the terminals of the tandem converter contains no voltage spikes since the DC-link capacitor of the secondary converter is always connected between each pair of input- and output lines (Trzynadlowski et al., 1998b).Concerning the dynamic properties, (Trzynadlowski et al., 1998a) states that the overall performance of the tandem converter is superior to both the CSC and the VSI. This is because current magnitude commands are handled by the voltage source converter, while phase-shift current commands are handled by the current source converter (Zhang et al., 1998b).Besides the main function, which is to compensate the current distortion introduced by the primary converter, the secondary converter may also act like an active resistor, providing damping of the primary inverter in light load conditions (Zhang et al., 1998b).1.2.5.2 Disadvantages of using the Tandem ConverterAn inherent obstacle to applying the tandem converter is the high number of components and sensors required. This increases the costs and complexity of both hardware and software. The complexity is justified by the redundancy of the system (Trzynadlowski et al., 1998a), however the system is only truly redundant if a reduction in power capability and performance is acceptable.Since the voltage across the generator terminals is set by the secondary inverter, the voltage stresses at the converter are high.Therefore the demands on the output filter are comparable to those when applying the back-to-back PWM-VSI.In the system shown in Figure 38, a problem for the tandem converter in comparison with the back-to-back PWM-VSI is the reduced generator voltage. By applying the CSI as the primary converter, only 0.866% of the grid voltage can be utilized. This means that the generator currents (and also the current through the switches) for the tandem converter must be higher in order to achieve the same power.1.2.6 Matrix converterIdeally, the matrix converter should be an all silicon solution with no passive components in the power circuit. The ideal conventional matrix converter topology is shown in Figure 8.Figure 8. The conventional matrix converter topology.The basic idea of the matrix converter is that a desired input current (to/from the supply), a desired output voltage and a desired output frequency may be obtained by properly connecting the output terminals of the converter to the input terminals of the converter. In order to protect the converter, the following two control rules must be complied with: Two (or three) switches in an output leg are never allowed to be on at the same time. All of the three output phases must be connected to an input phase at any instant of time. The actual combination of the switchesdepends on the modulation strategy.1.2.6.1 Advantages of using the Matrix ConverterThis section summarises some of the advantages of using the matrix converter in the control of an induction wind turbine generator. For a low output frequency of the converter the thermal stresses of the semiconductors in a conventional inverter are higher than those in a matrix converter. This arises from the fact that the semiconductors in a matrix converter are equally stressed, at least during every period of the grid voltage, while the period for the conventional inverter equals the output frequency. This reduces thethermal design problems for the matrix converter.Although the matrix converter includes six additional power switches compared to the back-to-back PWM-VSI, the absence of the DC-link capacitor may increase the efficiency and the lifetime for the converter (Schuster, 1998). Depending on the realization of the bi-directional switches, the switching losses of the matrix inverter may be less than those of the PWM-VSI, because the half of the switchings become natural commutations (soft switchings) (Wheeler & Grant, 1993).1.2.6.2 Disadvantages and problems of the matrix converterA disadvantage of the matrix converter is the intrinsic limitation of the output voltage. Without entering the over-modulation range, the maximum output voltage of the matrix converter is 0.866 times the input voltage. To achieve the same output power as the back-to-back PWM-VSI, the output current of the matrix converter has to be 1.15 times higher, giving rise to higher conducting losses in the converter (Wheeler & Grant, 1993).In many of the papers concerning the matrix converter, the unavailability of a true bi-directional switch is mentioned as one of the major obstacles for the propagation of the matrix converter. In the literature, three proposals for realizing a bi-directional switch exists. The diode embedded switch (Neft & Schauder, 1988) which acts like a truebi-directional switch, the common emitter switch and the common collector switch (Beasant et al., 1989).Since real switches do not have infinitesimal switching times (which is not desirable either) the commutation between two input phases constitutes a contradiction between the two basic control rules of the matrix converter. In the literature at least six different commutation strategies are reported, (Beasant et al., 1990); (Burany, 1989); (Jung & Gyu, 1991); (Hey et al., 1995); (Kwon et al., 1998); (Neft & Schauder, 1988). The most simple of the commutation strategies are those reported in (Beasant et al., 1990) and (Neft & Schauder, 1988), but neither of these strategies complies with the basic control rules.译文1 电力电子技术的内容电力电子技术是一门正在快速发展的技术,电力电子元器件有很高的额定电流和额定电压,它的功率减小元件变得更加可靠、耐用.这种元件还可以用来控制比它功率大很多倍的元件。
Chapter-09--Letters-of-Credit
➢ Kinds of L/Cs
▪ sight L/C ▪ term L/C =time L/C =usance L/C ▪ revocable L/C -- irrevocable L/C ▪ confirmed L/C -- unconfirmed L/C ▪ transferable L/C -- non-transferable L/C ▪ revolving L/C -- non-revolving L/C ▪ divisible L/C -- indivisible L/C ▪ clean L/C -- documentary L/C ▪ L/C without recourse -- L/C with recourse ▪ back to back L/C (reciprocal L/C )
电力电子技术中英文词汇对照表
电力电子技术中英文词汇对照表英文中文词汇对照AAbsorbe Circuit 吸收电路AC Controller 交流电力控制器AC power control 交流电力控制AC Power Controller 交流调功电路AC Power Electronic Switch 交流电力电子开关AC V oltage Controller 交流调压电路AC—AC Frequency Converter 交交变频电路Active Power Filter——APF 有源电力滤波器Asynchronous Modulation 异步调制BBaker Clamping Circuit 贝克箝位电路Band Gap,Energy Gap 禁带，带隙Bipolar Junction Transistor—BJT 双极结型晶体管Boost Chooper, Step Up Chopper 升压斩波电路Boost Converter ，Step Up Converter,Step Up Chopter Boost变换器,升压斩波电路Boost-Buck Chopper, Step Up & Down Chopper 升降压斩波电路Bridge Reversible Chopper 桥式可逆斩波电路Buck Chopper, Step Down Chopper 降压斩波器Buck Converter,Step Down Converter,Step Down Chopper Buck变换器，降压斩波电路Buck-Boost Converter,Step Down/Step Up Converter buck-boost变换器，升降压斩波电路CChopper Circuit 斩波电路Circulating Current 环流Commutation 换流，换相Conduction Angle 导通角Conductivity Modulation 电导调制Constant V oltage Constant Frequency—CVCF 恒压恒频电源Continuous Conduction Mode—CCM (电流)连续模式Control Circuit 控制电路Cuk Converter Cuk变换器，丘克变换器Current Reversible Chopper 电流可逆斩波电路Current Source Inverter—CSI 电流(源)型逆变电路Custom Power 用户电力技术，定制电力技术Cycloconvertor 周波变流器，周波变换器DC Chopper 直流斩波器DC Chopping Circuit 直流斩波电路DC-DC Converter 直流—直流变换器DC-AC-DC Converter 直交直电路Device Commutation 器件换流Direct Current Control 直接电流控制Discontinuous Conduction Mode—DCM 电流断续模式Displacement Factor 位移因数Distortion Power 畸变功率Double-Ended Converter 双端变换器Drift Region 漂移区Driving Circuit 驱动电路Dynamic V oltage Restorer—DVR 动态电压恢复器EElectrical Isolation 电气隔离Electrical AC Switch 交流电力电子开关Energy Band 能带FFactory Automation—FA 工厂自动化Fast Acting Fuse 快速熔断器Fast Recovery Diode—FRD 快恢复二极管Fast Recovery Epitaxial Diode—FRED 快恢复外延二极管Fast Switching Thyristor—FST 快速晶闸管Field Controllded Thyristor—FCT 场控晶闸管Field Effect Transistor—FET 场效应晶体管Fixed Capacitor—FC 固定电容器Flexible AC Transmission System—FACTS 柔性交流输电系统，灵活交流输电系统Flicker (电压)闪变Flyback Converter 反激电路Forced Commutation 强迫换流Forward Converter 正激变换器Frequency Inverter 变频器Full-Bridge Circuit 全桥电路Full-Bridge Rectifier 全桥整流电路Full-Wave Rectifier 全波整流电路Fundamental Component Factor,Distortion Factor 基波因数GGate Turn-Off Thyristor—GTO 可关断晶闸管General Purpose Diode 普通二极管Giant Transistor—GTR 电力晶体管HHalf-Bridge Circuit 半桥电路Hard Switching 硬开关Harmonic Ratio For In—HRIn n次谐波电流含有率Harmonics 谐波High Intensity Discharge lamp—HID 高强度放电灯High V oltage DC—Transmission—HVDC 高压直流输电High V oltage IC—HVIC 高压集成电路Hysteresis Control, Hysteretic Control 滞环控制IIndirect Current control 间接电流控制Indirect DC-DC Converter 间接直流变换电路Insulated-Gate Bipolar Transistor—IGBT 绝缘栅双极晶体管Integrated Gate-Commutated Thyristor—IGCT 集成门极换流晶闸管Intelligent Power Electronics Module—IPEM 集成电力电子模块Intelligent Power Module—IPM 智能功率模块Intrinsic Semiconductor 本征半导体Inversion 逆变JJunction FET—JFET 结型场效应晶体管LLatching Effect 擎住效应Leakage Indcutance 漏感Light Triggered Thyristor—LTT 光控晶闸管Line Commutation 电网换流Load Commutation 负载换流Loop Current 环流MMagnetic Core Reset 磁心复位Main Circuit, Power Circuit 主电路Matrix Frequency Converter 矩阵式变频电路MOS Controlled Thyristor—MCT MOS控制晶闸管Multi-Level Inverter 多电平逆变电路Multiplex 多重化Multiplex Inverter 多重逆变电路NNatural Sampling M ethod 自然采样法Neutral Point Clamped Inverter 中性点箝位型逆变电路OOff-State 断态(阻断状态)On-State 通态(导通状态)PParallel-Resonant Inverter 并联谐振式逆变电路Phase Controlled 相控Phase Shift Controlled Full Bridge Converter 移相全桥电路Power Conversion 电力变换Power Conversion Technique 交流技术Power Diode 电力二极管Power Electronic Device 电力电子器件Power Electronic System 电力电子系统Power Electronic Technology 电力电子技术Power Electronics 电力电子学Power Factor—PF 功率因数Power Factor Correction—PFC 功率因数校正Power Integrated Circuit—PIC 功率集成电路Power Module 功率模块Power MOSFET 电力场效应晶体管Power Semicondutor Device 电力半导体器件Pulse-Width Modulation—PWM 脉冲宽度调制Push-Pull Converter 推挽电路PWM Rectifier PWM整流电路PWM Tracking Control PWM跟踪控制QQuasi-Resonant 准谐振RReactive Invert 无源逆变Rectification 整流Rectifier 整流电路Rectifier Diode 整流二极管Regenerative Invert 有源逆变Resonant DC Link 谐振直流环电路Resonation 谐振Reverse Conducting Thyristor—RCT 逆导晶闸管Rule Sampling Method 规则采样法SSafe Operating Area—SOA 安全工作区Schottky Barrier Diode—SBD 肖持基势垒二极管Schottky Diode 肖特基二极管Second Breakdown 二次击穿Seleted Harmonic Elimination PWM—SHEPWM 特定谐波消去PWM Sepic Chopper Sepic斩波电路Silicon Controlled Rectifier—SCR 可控硅Single End Converter 单端电路Single-Phase Full-Bridge Controlled Rctifier 单相桥式全控整流电路Single-Phase Full-Bridge Inverter 单相全桥逆变电路Single-Phase Full-Wave Controlled Rectifier 单相全波可控整流电路Single-Phase Half-Bridge Inverter 单相半桥逆变电路Single-phase Half-Wave Controlled Rectifier 单相半波可控整流电路Sinusoidal PWM—SPWM 正弦PWMSmart Power IC—SPIC 智能功率集成电路Snubber Current 缓冲电路Soft Switching 软开关Static Induction Thyristor—SITH 静电感应晶闸管Static Induction Transistor—SIT 静电感应晶体管Static V ar Compensator —SVC 静止无功补偿器Switching Loss 开关损耗Switching Mode Power Supply 开关电源Switching Noise 开关噪声Synchronous Modulation 同步调制Synchronous Rectifier 同步整流电路TThree-Phase Full-Bridge Controlled Rectifier 三相桥式可控整流电路Three-Phase Half-Wave Controlled Rectifier 三相半波可控整流电路Thyristor 晶闸管Thyristor Controlled Reaction—TCR 晶闸管控制电抗器Thyristor Switched Capacitor—TSC 晶闸管投切电容器Total Harmonic Distortion for i—THD 谐波电流总畸变率Trigger 触发Trigger Angle 触发角Trigger Delay Angel 触发延迟角Triode AC Switch—TRIAC 双向晶闸管Turn-off 关断Turn-on 开通UUninterruptable Power Supply—UPS 不间断电源VV ariable V oltage Variable Frequency—VVVF 变压变频V oltage Source Type Inverter—VSTI 电压(源)型逆变电路ZZero Current 零电流Zero Switching 零开关Zero Transition 零转换Zero V oltage 零电压Zero V oltage Transition PWM Converter 零电压转换PWM电路Zeta Chopper Zeta斩波电路ZVS Quasi-Resonant Converter 零电压准谐振电路。
Chapter 09 Practical Application Issues of Power S
Power Electronics
S F
T
C
D
RC1பைடு நூலகம்RC2
SDC
LB M
U
RV RC3 RC4
RCD
图1-34
Lightening arrestor RC or RCD snubbers (will be discussed later) Zener diode, Metal Oxide Varistor (MOV), Break Over Diode (BOD)
Protection circuits Overvoltage protection Overcurrent protection
Snubber circuits—specific protection circuits that can limit du/dt or di/dt Turn-on snubber Turn-off snubber
5 uo ui
8 Error indicating
4 M57962L 13
1
3.1
+15V 100F 100F
13
6VEE
6
-10V
M57962L integrated driver chip
8
Power Electronics
9.2 Protection of power semiconductor devices
Power Electronics
4VCC
14
Detection circuit
1 Sensing
4.7k 8
1
Fast recovery diode trr≤ 0.2s
Timer and reset circuit
《电力电子技术 》课件
电机控制
电机控制是指通过电力电子技术实现对电机速度 、方向和位置的精确控制。
电机控制广泛应用于工业自动化、交通运输、家 用电器等领域，如变频空调、电动汽车等。
电机控制有助于提高能源利用效率，降低能耗， 实现更智能化的生产和制造。
新能源发电系统
新能源发电系统是指利用可再生能源进行发电 的系统，如太阳能、风能等。
、更高可靠性和更小体积的方向发展。
系统集成和智能化的发展
系统集成
随着电力电子系统规模的不断扩大，系统集成成为了一个重要的研究方向，通过将多个电力电子模块集成在一个系统 中，可以实现更高的功率密度和更小的体积。
智能化
智能化是电力电子技术的另一个重要发展方向，通过引入人工智能和机器学习等技术，可以实现电力电子系统的自适 应控制和智能管理，提高系统的稳定性和可靠性。
针对高效能转换的挑战，需要不断研 究和开发新的电力电子器件、电路拓 扑和控制策略，以实现更高的转换效 率和更低的能耗。
技术瓶颈
目前电力电子技术面临的主要挑战是 如何进一步提高转换效率，降低能耗 ，以满足不断增长的高效能转换需求 。
新材料和新技术的发展
01
新材料的应用
随着新材料技术的不断发展，新型半导体材料如碳化硅（SiC）和氮化
电力电子技术的应用实例
不间断电源（UPS）
不间断电源（UPS）是一种能够提供持续电力供应的电源设备，主要用于保护重要 设备和数据免受电力中断的影响。
UPS通过使用电力电子转换技术，将电池或其他形式的储能装置与电网连接，确保 在电网故障或停电时，能够继续为设备提供稳定的电力。
UPS在医疗、金融、通信等领域有广泛应用，对于保证关键设备和服务的正常运行 至关重要。
详细描述
chapter09
1. The polymerase chain reaction in outline 2. PCR in more detail 3. Applications of PCR
9.1 PCR in outline PCR reaction: ● Template ● Primers ● DNA polymerase
1. Denature
（变性）
2. Annealing
（退火）Байду номын сангаас
3. Extension
（延伸）
4. Cycling
PCR
9.2 PCR in more detail 1. Designing the oligonucleotide primers for a PCR
Primers: 根据位置分： 5’-end primer 3’-end primer Forward primer Reverse primer Sense primer Antisense primer Upstream primer Downstream primer
根据序列性质分： Specific primer (专一） Degenerated primer（兼并）
Random primer(随机)
The result of PCRs with well-designed and poorly-designed primers
Lane 1: good
Lane 2: nothing
(2) Cloning PCR products
● Using the property of Taq polymerase
T cloning vector vector Blunt end vector dTTP polymerase T tailed vector
Chapter-09
Criminal Enterprise Behavior
1. 2.
3.
4. 5. 6.
act quickly and precisely to make their activities harder to detect exploit perimeter via vulnerable ports use trojan horses (hidden software) to leave back doors for re-entry use sniffers to capture passwords do not stick around until noticed make few or no mistakes.
benign intruders might be tolerable
IDS / IPS / VPNs can help counter awareness led to establishment of CERTs
collect / disseminate vulnerability info / responses
benign: explore, still costs resources serious: access/modify data, disrupt system
range
led
to the development of CERTs intruder techniques & behavior patterns constantly shifting, have common features
Criminal Enterprise
organized
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Chapter 9
Practical Application Issues
of Power Semiconductor Devices
Measures to protect power semiconductor devices from overvoltage
Power Electronics
T S U C F D RC1 RC2 RV RC3
SDC
LB M
RC4
RCD
Lightening arrestor RC or RCD snubbers (will be discussed later) Zener diode, Metal Oxide Varistor (MOV), Break Over Diode (BOD)
11
Measures to protect power semiconductor devices from overcurrent
Power Electronics
Fuse Circuit breaker Protection with current feedback control in the control circuit Protection with overcurrent detection in the gate drive circuit—the fastest measure
12
Functions and classifications of snubbers
Power Electronics
Functions
Limiting voltages applied to devices during turn-off transients Limiting device currents during turn-on transients Limiting device current rising rate (di/dt) at device turn-on Limiting the rate of rise (du/dt) of voltages across devices during device turn-off Shaping the switching trajectory of the device
Classifications
According to different switching transients
– – Turn-off snubber (sometimes just called snubber) Turn-on snubber
According to the treatment of energy
– Power dissipating snubber – Lossless snubber 13
Operation principle of typical snubbers
Power Electronics
Circuit configuration
uCE iC
without turn-off snubber without turn-on snubber iC uCE
Ri VDi Li
Turn-on snubber
O
with turn-off snubber
t
with turn-on snubber
Turn-off snubber
iC
V
VDs
Rs
A
B without turn-off snubber
Cs
L VD
O
D
with turn-off snubber C uCE
Switching trajectory
14
Other turn-off snubbers
Power Electronics
L
Rs
L Turn-off snubber Ed Cs VDs Rs Load Turn-off snubber
Ed
Cs Load
15
Power Electronics
9.3 Series and parallel connections of power semiconductor devices
Object To increase the capability to deal with voltage or current Issues and solutions Series connection
– Issue: even voltage sharing – Solutions:
• Selection of devices that are closer to each other in the characteristics characteristics • Voltage sharing circuit
Parallel connection
– Issue: even current sharing – Solutions:
• Selection of devices that are closer to each other in the characteristics characteristics • Current sharing circuit and symmetrical circuit layout
16
Series Connection of thyristors
Power Electronics
I
VT1 VT2 VT1 RP R C R C
IR O UT1 UT2 U VT2 RP
a)
b)
Voltage sharing circuit
– Steady-state voltage sharing circuit – Dynamic voltage sharing circuit
17
Parallel Connection of Power MOSFETs
Power Electronics
Easy to realize because of the positive temperature of their onstate resistance Need a small damping resistor in series with the individual gate connections Still need to select devices that are closer to each other in the characteristics Circuit layout should be symmetrical
18
。