电气工程专业英语+unt1教学课件.ppt

1、电气工程及其自动化专业英语电气工程及其自动化专业英语主编主编 杨勇杨勇 邓秋玲邓秋玲1 CONTENTS Unit 1 Fundamentals of Electronic Circuits Unit 2 Power Electronics Unit 3 Electrical MachinesUnit 4 Electric Power Systems Unit 5 Electric Power Generations Unit 6 Automatic Control Unit 7 Sensoring Technology Unit 8 Computer Network and Networke

2、d Control Unit 9 Signal Processing 2Unit 1 Fundamentals of Electronic Circuits Unit 1 Fundamentals of Electronic Circuits 1.1 Introduction to Circuit Theory 1.1 Introduction to Circuit Theory 1.2 Analog and Digital Circuits 1.2 Analog and Digital Circuits 1.3 Three-Phase Circuits1.3 Three-Phase Circ

3、uits1.4 Further Reading1.4 Further Reading31.1 Introduction to Circuit TheoryNew Words and Expressionse element n.成分成分；元件元件i interconnect vt.使互相连接使互相连接n node n n.节点节点b branch n n.分枝；分部；支流分枝；分部；支流 v v.出现分歧出现分歧l loop n.循环，回路循环，回路;vt.使成环；使成环；t topology n n.拓扑；布局；拓扑学拓扑；布局；拓扑学c configuration n n.构造；结构；配置

4、；外形构造；结构；配置；外形 t terminal n n.终点站；终端；接线端终点站；终端；接线端41.1 Introduction to Circuit TheoryNew Words and Expressionsresistor n.电电电阻器电阻器independent adj.独立自主的；不受约束的独立自主的；不受约束的series n.连续；系列；级数；串联连续；系列；级数；串联parallel adj.平行的；并联的平行的；并联的 n.平行线；平平行线；平 行面；行面；v.相应；平行相应；平行impedance n.电电阻抗；全电阻；阻抗；全电阻；物物阻抗阻抗theorem n

5、.数数定理；法则定理；法则5NoteNote：providing one or more closed paths为为network的后置定语。的后置定语。1.1 Introduction to Circuit Theory textNoteNote：differentiate在此处为动词，在此处为动词，differentiate between A A and B B表示区分表示区分A和和B；To differentiate between a circuit and a network是目的状语从句是目的状语从句.NoteNote：regard as表示表示“把把认为认为”(1)Nodes

6、,Branches and Loops Since the elements of an electric circuit can be interconnected in several ways,we need to understand some basic concepts of network topology.To differentiate between a circuit and a network,we may regard a network as an interconnection of elements or devices,whereas a circuit is

7、 a network providing one or more closed paths.61.1 Introduction to Circuit Theory textIn network topology,we study the properties relating to(关于关于.的特性的特性)the placement of elements in the network and the geometric configuration of the network.Such elements include branches,nodes,and loops.A branch re

8、presents a single element such as a voltage source or a resistor.In other words,a branch represents any two-terminal element.The circuit in Fig.1.1 has five branches,namely,the 10V voltage source,the 2A current source,and the three resistors.A node is the point of connection between two or more bran

9、ches.71.1 Introduction to Circuit Theory textA node is usually indicated by a dot in a circuit.If a short circuit(a connecting wire)connects two nodes,the two nodes constitute a single node.The circuit in Fig.1.1 has three nodes a,b,and c.Notice that the three points that form node b are connected b

10、y perfectly conducting wires and therefore constitute a single point.Note:Note:t three points that form node b 表示表示形成节点形成节点b b的的3个点个点.此句可译为此句可译为:注意到形成节点注意到形成节点b b的的3个点是通过理个点是通过理想导线相连接的，因此组成了想导线相连接的，因此组成了1个节点个节点.81.1 Introduction to Circuit Theory textThe same is true of the four points forming node

11、c.We demonstrate that(证明)the circuit in Fig.1.1 has only three nodes by redrawing the circuit in Fig.1.2.The two circuits in Fig.1.1 and Fig.1.2 are identical.However,for the sake of clarity,nodes b and c are spread out with perfect conductors as in Fig.1.2.Note:：the same is true of:这也适用于这也适用于，也是如此。

12、也是如此。Note:：for the sake of clarity:为清楚起见为清楚起见;：spread out:伸展伸展;spread out with perfect conductors：用理想导线分散开。：用理想导线分散开。91.1 Introduction to Circuit Theory textA loop is any closed path in a circuit.A loop is a closed path formed by starting at a node,passing through a set of nodes,and returning to the

13、 starting node without passing through any node more than once.A loop is said to be（可认为是）independent if it contains a branch which is not in any other loop.Independent loops or paths result in（导致导致,结果是）结果是）independent sets of equations.Note:：回路回路是一个是一个闭合闭合的的路径路径，它是，它是从一个从一个节节点开点开始，经过若干始，经过若干节节点，再回到起

14、始点，再回到起始节节点，点，任意一个节点只经任意一个节点只经过一次过一次。101.1 Introduction to Circuit Theory textFor example,the closed path abca containing the 2 resistor in Fig.1.2 is a loop.Another loop is the closed path bcb containing the 3 resistor and the current source.Although one can identify six loops in Fig.1.2,only three

15、 of them are independent.A network with b branches,n nodes,and l independent loops will satisfy the fundamental theorem of network topology:b=l+n-1(1.1)Note：containing the 2 resistor 作定语修饰作定语修饰 closed path abca，意为包含意为包含2电阻的闭合路径电阻的闭合路径abca。111.1 Introduction to Circuit Theory textAs the next two defi

16、nitions show,circuit topology is of great value（=is very valuable）to the study of voltages and currents in an electric circuit.Two or more elements are in series（串联）（串联）if they are cascaded or connected sequentially（接顺序连接）（接顺序连接）and consequently carry the same current（流过相同电流流过相同电流）.Two or more eleme

17、nts are in parallel（并联并联）if they are connected to the same two nodes and consequently have the same voltage across them.Note:Note:：voltage across them表示关于两节点之间的电压，表示关于两节点之间的电压，“them”指代指代“two nodes”。121.1 Introduction to Circuit Theory textElements may be connected in a way that they are either in se

18、ries or in parallel.In the circuit shown in Fig.1.1,the voltage source and the 5 resistor are in series because the same current will flow through them.The 2 resistor,the 3 resistor,and the current source are in parallel because they are connected to the same two nodes(b and c)and consequently have

19、the same voltage across them.The 5 and 2 resistors are neither in series nor in parallel with each other.Note：修饰电流的介词短语用修饰电流的介词短语用through，：修饰电压修饰电压用用across。them代表代表 resistors131.1 Introduction to Circuit Theory text(2)Ohms Law，Kirchhoffs Current Law(KCL)and Kirchhoffs Voltage Law(KVL)Ohms Law states

20、 the voltage across a resistor,R(or impedance,Z)is directly proportional to（与.成比例）the current passing through it(the resistance/impedance is the proportionality constant).(1.2)Note:Note:：proportionality constant是比例系数。是比例系数。：DC:表示表示direct current;AC表示表示alternating current。DC:AC:viRVIZ141.1 Introducti

21、on to Circuit Theory textOhms Law by itself is not sufficient to analyze circuits.However,when it is coupled with Kirchhoffs two laws,we have a sufficient,powerful set of tools for analyzing a large variety of electric circuits.Kirchhoffs laws were first introduced in 1847 by the German physicist Gu

22、stav Robert Kirchhoff(18241887).These laws are formally known as Kirchhoffs Current Law(KCL)and Kirchhoffs Voltage Law(KVL).Note:Note:by itself：本身；：本身；is coupled with：加上，与加上，与.结结合起来。合起来。are formally known as：被正式称为。：被正式称为。151.1 Introduction to Circuit Theory textKirchhoffs First Law is based on the l

23、aw of conservation of charge,which requires that the algebraic sum（代数和代数和）of charges within a system cannot change.Kirchhoffs Current Law(KCL)states that the algebraic sum of currents entering a node(or a closed boundary)is zero.Kirchhoffs First Law：基尔霍夫第一定律；：基尔霍夫第一定律；law of conservation of charge：电

24、荷守恒定律：电荷守恒定律.161.1 Introduction to Circuit Theory textMathematically,KCL implies that:(1.3)where N is the number of branches（支路数）connected to the node and in is the nth current entering(or leaving)the node.By this law,currents entering a node may be regarded as positive,while currents leaving the no

25、de may be taken as（可认为是）negative or vice versa.Note:Note:By this law:根据这个定律；根据这个定律；vice versa：反过来也一样；反之亦然。：反过来也一样；反之亦然。10Nnni171.1 Introduction to Circuit Theory textConsider the node in Fig.1.3.Applying KCL gives:i1-i2+i3+i4-i5=0 (1.4)since currents i1,i3,and i4 are entering the node,while currents

26、 i2 and i5 are leaving it.By rearranging the terms（项）,we get:i1+i3+i4=i2+i5(1.5)Eq.(1.5)is an alternative form（另一种形式）of KCL.The sum of the currents entering a node is equal to（等于）the sum of the currents leaving the node.181.1 Introduction to Circuit Theory textNote that KCL also applies to a closed

27、boundary.This may be regarded as a generalized case,because a node may be regarded as a closed surface shrunk to a point.In two dimensions,a closed boundary is the same as a closed path.As typically illustrated in the circuit of Fig.1.4,the total current entering the closed surface is equal to the t

28、otal current leaving the surface.applies to：适用于；适用于；generalized case：一般的情况；一般的情况；As illustrated：如图所示：如图所示.191.1 Introduction to Circuit Theory textKirchhoffs voltage law(KVL)states that the algebraic sum of all voltages around a closed path(or loop)is zero.Expressed mathematically,KVL states that:(1

29、.6)where M is the number of voltages in the loop(or the number of branches in the loop)and vm is the mth voltage.Note:Note:式中，式中，M是回路中的电压个数（或回路中的支路数），是回路中的电压个数（或回路中的支路数），vm是第是第m条支路上电压。条支路上电压。10Mmmv20各个电压的符号就是沿着环路绕行方向首先遇到的端子的极各个电压的符号就是沿着环路绕行方向首先遇到的端子的极性。绕行可以从任一支路开始，绕行方向可以是顺时针，也可性。绕行可以从任一支路开始，绕行方向可以是顺

30、时针，也可以是逆时针。以是逆时针。1.1 Introduction to Circuit Theory textTo illustrate KVL,consider the circuit in Fig.1.5.The sign on each voltage is the polarity of the terminal encountered first as we travel around the loop.We can start with any branch and go around the loop either clockwise or counterclockwise.S

31、uppose we start with the voltage source and go clockwise around the loop as shown;then voltages would be v1,+v2,+v3,v4,and+v5,in that order.假设从电压源开始，顺时针绕回路一圈，那么按顺序，各个假设从电压源开始，顺时针绕回路一圈，那么按顺序，各个电压符号分别为电压符号分别为v1、+v2、+v3、v4、+v5。211.1 Introduction to Circuit Theory textFor example,as we reach branch 3,th

32、e positive terminal is met first;hence we have+v3.For branch 4,we reach the negative terminal first;hence,（此处省略了we have）v4.Thus,KVL yields:-v1+v2+v3-v4+v5=0(1.7)Rearranging terms gives:重新整理各项可以得到：重新整理各项可以得到：v2+v3+v5=v1+v4(1.8)which may be interpreted as:Sum of voltage drops=Sum of voltage rises(1.9)

33、Note：voltage drops：电压降；：电压降；voltage rises：电压升电压升221.1 Introduction to Circuit Theory textThis is an alternative form of KVL.Notice that if we had traveled counterclockwise,the result would have been+v1,-v5,+v4,-v3,and-v2,which is the same as before except that the signs are reversed.Hence,Eqs.(1.7)a

34、nd(1.8)remain the same.When voltage sources are connected in series,KVL can be applied to obtain the total voltage.The combined voltage is the algebraic sum of the voltages of the individual sources.Note:Note:combined voltage：总电压。：总电压。231.2 Analog and Digital Circuits New Words and Expressionsanalog

35、 n.类似物类似物；模拟模拟digital adj.数字的数字的；n.数字数字；数字式数字式thermometer n.温度计温度计；体温计体温计Fahrenheit adj.华氏温度计的华氏温度计的 n.华氏温度计华氏温度计drum n.鼓形圆桶鼓形圆桶 v.打鼓打鼓 discrete adj.不连续的不连续的；离散的离散的original adj.最初的最初的；原始的原始的；n.原物原物；原作原作remote adj.遥远的遥远的；偏僻的偏僻的；细微的细微的bulb n.鳞茎鳞茎；球形物球形物Morse code 莫莫尔斯电码尔斯电码 pulse n.脉搏脉搏；脉冲脉冲 241.2 Ana

36、log and Digital Circuits New Words and Expressionsbuzzer n.嗡嗡作声的东西嗡嗡作声的东西；蜂鸣器蜂鸣器；信号手信号手manipulate vt.（熟练地熟练地）操作操作；利用利用；应付应付destination n.目的地；目的单元格目的地；目的单元格 humidity n.湿气；潮湿；湿度湿气；潮湿；湿度interface n.接触面；界面接触面；界面 comparator n.比较仪比较仪 trigger vt.引起；触发引起；触发 vi.转移；转移；n.扳机扳机 sequence n.次序；顺序；序列次序；顺序；序列 serial

37、 adj.连续的；串行的；顺次连续的；串行的；顺次decoder n.解码器解码器reassemble vt.重新召集重新召集 vi.重新集合重新集合 25(1)Analog Analog quantities vary continuously,and analog systems represent the analog information using electrical signals that vary smoothly and continuously over a range.A good example of an analog system is the recordin

38、g thermometer,the actual equipment is shown in Fig.1.6.1.2 Analog and Digital Circuits TEXTNote：模拟系统通过在某一范围内平滑而连续地变化模拟系统通过在某一范围内平滑而连续地变化的电信号反映模拟信息。的电信号反映模拟信息。26An ink pen records the temperature in degrees Fahrenheit(F)and plots it continuously against time on a special graph paper attached to a dru

39、m as the drum rotates.Note that the temperature changes smoothly and continuously.There are no abrupt steps or breaks in the data.1.2 Analog and Digital Circuits TEXTNote：用一张特殊的方格纸系在一个鼓上，当鼓转动用一张特殊的方格纸系在一个鼓上，当鼓转动时，墨水笔连续记录下温度（华氏温度时，墨水笔连续记录下温度（华氏温度F F），并把温度随），并把温度随时间的变化曲线描绘在这张专用的方格纸上。时间的变化曲线描绘在这张专用的方格纸

40、上。27(2)Digital Digital quantities vary in discrete levels(离散级）.In most cases,the discrete levels(离散电平）are just two valuesON and OFF.Digital systems carry information using combinations of ON-OFF electrical signals that are usually in the form of codes that represent the information.The telegraph sys

41、tem is an example of a digital system.1.2 Analog and Digital Circuits TEXTNote：in the form of：以以.的形式。数字系统通过导通和的形式。数字系统通过导通和截止的电信号组合来表示信息，通常以编码的形式反映出来。截止的电信号组合来表示信息，通常以编码的形式反映出来。28The system shown in Fig.1.7 is a simplified version of the original telegraph system,but it will demonstrate the principl

42、e and help to define a digital system.1.2 Analog and Digital Circuits TEXT29The electrical circuit(as shown in Fig.1.7(a)is a battery with a switch in the line at one end and a light bulb at the other.The person at the switch position is remotely located from the person at the light bulb.The informa

43、tion is transmitted from the person at the switch position to the person at the light bulb by coding the information to be sent using the international Morse telegraph code.1.2 Analog and Digital Circuits TEXTNote：is remotely located from（远离）Note：transmitted from.to；从.传递到.；Note：information to be sen

44、t：要传递的信息30Morse code uses short pulses(dots)and long pulses(dashes)of current to form the code for letters or numbers as shown in Fig.1.7(b).As shown in Fig.1.7(c),combining the codes of dots and dashes for the letters and numbers into words sends the information.1.2 Analog and Digital Circuits TEXT

45、Note：code for letters or numbers：字符码或数字码；Note：combining the codes of dots and dashes for the letters and numbers into words 是动名词词组作主语。意为：对代表字母和数字的点和破折号进行组合来发送信息。31The sender keeps the same shorter time interval between letters but a longer time interval between words.This allows the receiver to iden

46、tify that the code sent is a character in a word or the end of a word itself.1.2 Analog and Digital Circuits TEXTNote：发送者在字母之间保持着相同的较短时间间隔，而在词之间保持较长时间间隔。这就使接收者能分辨出传送码是一个词中的字符，还是一个单词本身的结束。32The T is one dash(one long current pulse).The H is four short dots(four short current pulses).The R is a dot-da

47、sh-dot,and the two Es are a dot each.The two states are ON and OFFcurrent or no current.The person at the light bulb position identifies the code by watching the glow of the light bulb.In the original telegraph,this person listened to a buzzer or“sounder”to identify the code.1.2 Analog and Digital C

48、ircuits TEXT T表示破折号（一个长电流脉冲）。H是4个短点（4个短电流脉冲）。R是点-破折号-点的组合。两个E时，则一个点代表一个E。ON 和 OFF两种状态分别表示有电流和无电流。33Coded patterns of changes from one state to another as time passes carry the information.At any instant of time the signal is either one of two levels.The variations in the signal are always between se

49、t discrete levels,but,in addition,a very important component of digital systems is the timing of signals.1.2 Analog and Digital Circuits TEXTNote：随时间从一个状态变化到另一个状态的编码图随时间从一个状态变化到另一个状态的编码图携带信息。携带信息。At any instant of time：任何一个时刻34In many cases,digital signals,either at discrete levels,or changing betwe

50、en discrete levels,must occur precisely at the proper time or the digital system will not work.Timing is maintained in digital systems by circuits called system clocks.This is what identifies a digital signal and the information being processed in a digital system.1.2 Analog and Digital Circuits TEX