电气工程专业英语+unt1

1、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 2 CONTENTS Unit 1 Fundamentals of Electronic Circuits Unit 2 Power Electronics Unit 3 Electrical Machines Unit 4 Electric Power Systems Unit 5 Electric Power Generations Unit 6 Automatic Control Unit 7 Sensoring Technology Unit 8 Computer Network and Net

2、worked Control Unit 9 Signal Processing 3 Unit 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-Phas

3、e Circuits 1.4 Further Reading1.4 Further Reading 4 1.1 Introduction to Circuit Theory New Words and Expressions e 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

4、局；拓扑学 c configuration n n. . 构造；结构；配置；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 5 1.1 Introduction to Circuit Theory New Words and Expressions resistor 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.

5、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. 数数定理；法则定理；法则 6 NoteNote：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 text NoteNote：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

6、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, 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 ne

7、twork as an interconnection of elements or devices, whereas a circuit is a network providing one or more closed paths. 7 1.1 Introduction to Circuit Theory text In 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 configurat

8、ion of the network. Such elements include branches, nodes, and loops. A branch represents 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 so

9、urce, and the three resistors. A node is the point of connection between two or more branches. 8 1.1 Introduction to Circuit Theory text A 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 i

10、n Fig.1.1 has three nodes a, b, and c. Notice that the three points that form node b are connected by 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

11、连接的，因此组成了1个节点个节点. . 9 1.1 Introduction to Circuit Theory text The same is true of the four points forming node 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

12、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。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。 10 1.1 Introduction to Circuit Theory text A loop is any

13、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 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. Independe

14、nt 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。 11 1.1 Introduction to Circuit Theory text For example, the closed path abca containing the 2 resistor in Fig.1.2 is a loo

15、p. 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 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

16、-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。 12 1.1 Introduction to Circuit Theory text As the next two definitions show, circuit topology is of great value （=is very valuable）to the study of voltages and currents in an electric circuit. Two or mor

17、e 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 elements 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:：v

18、oltage 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 ”。 13 1.1 Introduction to Circuit Theory text Elements may be connected in a way that they are either in series or in parallel. In the circuit shown in Fig.1.1, the voltage source and the 5 resistor are in series because the same curr

19、ent 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 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

20、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 resistors 14 1.1 Introduction to Circuit Theory text (2) Ohms Law，Kirchhoffs Current Law (KCL) and Kirchhoffs Voltage Law (KVL) Ohms Law states the voltage across a resistor, R (or impedance, Z) is directly proportional to （与.成比例） the current passing t

21、hrough 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: viR VIZ 15 1.1 Introduction to Circuit Theory text Ohms Law by itself is not sufficient to analyze circuits. However,

22、 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 Gustav Robert Kirchhoff (18241887). These laws are formally known as Kirchhoffs Current

23、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。 16 1.1 Introduction to Circuit Theory text Kirchhoffs First Law is based on the law of conservation of charge, which requires that the algebraic sum （代

24、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：电荷守恒定律：电荷守恒定律. 17 1.1 Introduction to Circuit Theory text Math

25、ematically, 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 node may be taken as （可认为是）negative or vice versa.

26、 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。 1 0 N n n i 18 1.1 Introduction to Circuit Theory text Consider 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 i2 and i5 are lea

27、ving 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. 19 1.1 Introduction to Circuit Theory text Note that KCL also applies to a close

28、d 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

29、to the total 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. 20 1.1 Introduction to Circuit Theory text Kirchhoffs voltage law (KVL) states that the algebraic sum of all voltages around a closed path (or loop) is zero. Expressed mathematicall

30、y, KVL states that: (1.6) 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。 1 0 M m m v 21 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

31、，绕行方向可以是顺时针，也可性。绕行可以从任一支路开始，绕行方向可以是顺时针，也可 以是逆时针。以是逆时针。 1.1 Introduction to Circuit Theory text To 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 l

32、oop either clockwise or counterclockwise. Suppose 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。 22 1.1 Introduction to Cir

33、cuit Theory text For example, as we reach branch 3, the 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

34、 + v4(1.8) which may be interpreted as: Sum of voltage drops= Sum of voltage rises(1.9) Note：voltage drops：电压降；：电压降； voltage rises：电压升电压升 23 1.1 Introduction to Circuit Theory text This is an alternative form of KVL. Notice that if we had traveled counterclockwise, the result would have been +v1,-v5

35、, +v4,-v3, and-v2, which is the same as before except that the signs are reversed. Hence, Eqs.(1.7) and (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 sou

36、rces. Note:Note: combined voltage ：总电压。：总电压。 24 1.2 Analog and Digital Circuits New Words and Expressions analog 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 a

37、dj. 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 25 1.2 Analog and Digital Circuits New Words and Expressions buzzer 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 hu

38、midity 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 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 26 (1) Analog Analog quantities vary continuously, and analog system

39、s represent the analog information using electrical signals that vary smoothly and continuously over a range. A good example of an analog system is the recording thermometer, the actual equipment is shown in Fig. 1.6. 1.2 Analog and Digital Circuits TEXT Note：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

40、 的电信号反映模拟信息。的电信号反映模拟信息。 27 An ink pen records the temperature in degrees Fahrenheit (F) and plots it continuously against time on a special graph paper attached to a drum as the drum rotates. Note that the temperature changes smoothly and continuously. There are no abrupt steps or breaks in the data

41、. 1.2 Analog and Digital Circuits TEXT Note：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上。 28 (2) Digital Digital quantities vary in discrete levels(离散级）. In most cases, the discrete levels(离散电平） are just two valu

42、es ON 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 system is an example of a digital system. 1.2 Analog and Digital Circuits TEXT Note：in the form of ：以以.的形式。数字系统通过导通和的形式

43、。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。 29 The system shown in Fig.1.7 is a simplified version of the original telegraph system, but it will demonstrate the principle and help to define a digital system. 1.2 Analog and Digital Circuits TEXT 30 The electrical circuit (as sho

44、wn 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 information is transmitted from the person at the switch position to the person at the light bulb by coding t

45、he information to be sent using the international Morse telegraph code. 1.2 Analog and Digital Circuits TEXT Note： is remotely located from （远离） Note： transmitted from . to；从.传递到.； Note： information to be sent ：要传递的信息 31 Morse code uses short pulses (dots) and long pulses (dashes) of current to form

46、 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 Note： code for letters or numbers：字符码或数字码； Note： combining the codes of dots and

47、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。 32 The sender keeps the same shorter time interval between letters but a longer time interval between words.This allows the receiver to identify that the code sent is a character in a word or the end of a word itsel

48、f. 1.2 Analog and Digital Circuits TEXT Note：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。 33 The T is one dash (one long current pulse). The H is four short dots (four short current pulses). The R is a dot-dash-dot, and the two Es are a dot each. The two states are ON and

49、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 Circuits 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

50、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。 34 Coded 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 set discrete levels, but, in addition, a very importa

51、nt component of digital systems is the timing of signals. 1.2 Analog and Digital Circuits TEXT Note：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 35 In many cases, digital signals, either at discrete levels, or changing between discrete levels, must occur precisely

52、 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 TEXT Note：通过系统时针电路来维持数字系统的计时。通过系统时针电路来维

53、持数字系统的计时。 Note：这就是在数字系统中识别被处理的数字信号和这就是在数字系统中识别被处理的数字信号和 信息的方法。信息的方法。 36 (3) Quantities The temperature, pressure, humidity and wind velocity in our environment all change smoothly and continuously, and in many cases, slowly. Instruments that measure analog quantities usually have slow response and l

54、ess than high accuracy. To maintain an accuracy of 0.1% or 1 part in 1000 is difficult with an analog instrument. 1.2 Analog and Digital Circuits TEXT Note： 0.1% or 1 part in 1000 ：百分之零点一或千分之一。：百分之零点一或千分之一。 37 Digital quantities, on the other hand, can be maintained at very high accuracy and measure

55、d and manipulated at very high speed. The accuracy of the digital signal is in direct relationship to the number of bits used to represent the digital quantity. For example, using 10 bits, an accuracy of 1 part in 1024 is assured. 1.2 Analog and Digital Circuits TEXT Note：is in direct relationship t

56、o.与.有直接的关系； Note： number of bits位数； 38 Using 12 bits gives four times the accuracy (1 part in 4096), and using 16 bits gives an accuracy of 0.0015%, or 1 part in 65 536. This accuracy can be maintained as digital quantities are manipulated and processed very rapidly, millions of times faster than an

57、alog signals . 1.2 Analog and Digital Circuits TEXT Note：对数字量进行高速操作和处理时，仍然能保持对数字量进行高速操作和处理时，仍然能保持 这样的精度，因为数字信号的处理速度要比模拟信号的快这样的精度，因为数字信号的处理速度要比模拟信号的快 数百万倍。数百万倍。 39 As a result, if analog quantities are required to be processed and manipulated, the new design technique is to first convert the analog q

58、uantities to digital quantities, to process them in digital form, to reconvert the result to analog signals and to output them to their destination to accomplish a required task. 1.2 Analog and Digital Circuits TEXT 40 The complete procedure is indicated in Fig.1.8, and the need for analog circuits,

59、 digital circuits and the conversion circuits between them is immediately apparent. Fig.1.8 A typical system describing the functions in the analog-to-digital and digital-to-analog chain 41 (4) Analog-to-Digital Conversion (A/D) Fig.1.9 separates out the analog-to-digital portion of the Fig.1.8 chai

60、n to expand the basic functions in the chain. Most of natures inputs such as temperature, pressure, humidity, wind velocity, speed, flow rate, linear motion or position are not in a form to input them directly to electronic systems. They must be changed to an electrical quantitya voltage or a curren