1、电气工程及其自动化专业英语,主编 杨勇 邓秋玲,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 Networked Control Unit 9 Si
2、gnal Processing,Unit 1 Fundamentals of Electronic Circuits,1.1 Introduction to Circuit Theory,1.2 Analog and Digital Circuits,1.3 Three-Phase Circuits,1.4 Further Reading,1.1 Introduction to Circuit Theory,New Words and Expressions,element n. 成分；元件 interconnect vt. 使互相连接 node n. 节点 branch n. 分枝；分部；支
3、流 v. 出现分歧 loop n. 循环，回路; vt. 使成环； topology n. 拓扑；布局；拓扑学 configuration n. 构造；结构；配置；外形 terminal n. 终点站；终端；接线端,1.1 Introduction to Circuit Theory,New Words and Expressions,resistor n. 电电阻器 independent adj. 独立自主的；不受约束的 series n. 连续；系列；级数；串联 parallel adj. 平行的；并联的 n. 平行线；平 行面；v. 相应；平行 impedance n. 电阻抗；全电阻
4、；物阻抗 theorem n. 数定理；法则,Note：providing one or more closed paths为network的后置定语。,1.1 Introduction to Circuit Theorytext,Note：differentiate在此处为动词，differentiate between A and B表示区分A和B；To differentiate between a circuit and a network是目的状语从句.,Note：regard as表示“把认为”,(1) Nodes, Branches and LoopsSince the elem
5、ents 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 a network providing one or mo
6、re closed paths.,1.1 Introduction to Circuit Theorytext,In network topology, we study the properties relating to (关于.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 represents a single element suc
7、h 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 branches.,1.1 Introductio
8、n to Circuit Theorytext,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 in Fig.1.1 has three nodes a, b, and c. Notice that the three points that form node b are connected by perfectly c
9、onducting wires and therefore constitute a single point.,Note: “three points that form node b “表示“形成节点b的3个点“.此句可译为:注意到形成节点b的3个点是通过理想导线相连接的，因此组成了1个节点.,1.1 Introduction to Circuit Theorytext,The same is true of the four points forming node c. We demonstrate that (证明 )the circuit in Fig.1.1 has only th
10、ree 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，也是如此。,Note: ：for the sake of clarity:为清楚起见 ;：spread out:伸展;spre
11、ad out with perfect conductors ：用理想导线分散开。,1.1 Introduction to Circuit Theorytext,A 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 starting node without passing through any node more than once.,A loop is
12、 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,结果是） independent sets of equations.,Note:：回路是一个闭合的路径，它是从一个节点开始，经过若干节点，再回到起始节点，任意一个节点只经过一次。,1.1 Introduction to Circuit Theorytext,For example, the closed path abca containin
13、g 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 of them are independent.A network with b branches, n nodes, and l independent loops will satisfy the fundamental the
14、orem of network topology:b = l + n-1 (1.1),Note：containing the 2 resistor 作定语修饰 closed path abca ，意为包含2电阻的闭合路径abca。,1.1 Introduction to Circuit Theorytext,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 circ
15、uit. Two or more elements are in series （串联）if they are cascaded or connected sequentially （接顺序连接）and consequently carry the same current（流过相同电流）. Two or more elements are in parallel （并联）if they are connected to the same two nodes and consequently have the same voltage across them.,Note:：voltage ac
16、ross them表示关于两节点之间的电压，“them”指代“two nodes ”。,1.1 Introduction to Circuit Theorytext,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 current will flow through them. T
17、he 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：修饰电流的介词短语用through，：修饰电压用across。them代表
18、 resistors,1.1 Introduction to Circuit Theorytext,(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 through it (the resistance/impedance is the proportio
19、nality constant).(1.2),Note:：proportionality constant是比例系数。：DC:表示direct current; AC表示alternating current。,1.1 Introduction to Circuit Theorytext,Ohms 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
20、 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 Law (KCL) and Kirchhoffs Voltage Law (KVL).,Note: by itself ：本身； is coupled with： 加上，与.结合
21、起来。 are formally known as ：被正式称为。,1.1 Introduction to Circuit Theorytext,Kirchhoffs First Law is based on the law of conservation of charge, which requires that the algebraic sum （代数和）of charges within a system cannot change. Kirchhoffs Current Law (KCL) states that the algebraic sum of currents ent
22、ering a node (or a closed boundary) is zero.,Kirchhoffs First Law：基尔霍夫第一定律； law of conservation of charge：电荷守恒定律.,1.1 Introduction to Circuit Theorytext,Mathematically, 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)
23、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.,Note: By this law: 根据这个定律； vice versa：反过来也一样；反之亦然。,1.1 Introduction to Circuit Theorytext,Consider the node in Fig.1.3. Applying KCL gives: i1 - i
24、2 + i3 + i4 - i5 = 0 (1.4) since currents i1, i3, and i4 are entering the node, while currents 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
25、the currents leaving the node.,1.1 Introduction to Circuit Theorytext,Note that KCL also applies to a closed 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.
26、As typically illustrated in the circuit of Fig.1.4, the total current entering the closed surface is equal to the total current leaving the surface., applies to：适用于；, generalized case：一般的情况；, As illustrated ：如图所示.,1.1 Introduction to Circuit Theorytext,Kirchhoffs voltage law (KVL) states that the al
27、gebraic sum of all voltages around a closed path (or loop) is zero. Expressed mathematically, 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:式中，M是回路中的电压个数（或回路中的支路数），vm是第m条支路上电压。,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。
28、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。,1.1 Introduction to Circuit Theorytext,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 loop either clockwise or
29、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，各个电压符号分别为v1、+v2、+v3、v4、+v5。,1.1 Introduction to Circuit Theorytext,For example, as we reach branch 3, the positi
30、ve 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：v2 + v3 + v5 = v1 + v4 (1.8) which may be interpreted as: Sum of voltage drops= Sum of volta
31、ge rises (1.9),Note：voltage drops：电压降； voltage rises：电压升,1.1 Introduction to Circuit Theorytext,This 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. He
32、nce, 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 sources.,Note: combined voltage ：总电压。,1.2 Analog and Digital CircuitsNew Words and Expre
33、ssions,analog n. 类似物；模拟 digital adj. 数字的； n. 数字；数字式 thermometer n. 温度计；体温计 Fahrenheit adj. 华氏温度计的 n. 华氏温度计 drum n.鼓形圆桶 v. 打鼓 discrete adj. 不连续的；离散的 original adj. 最初的；原始的； n. 原物；原作 remote adj. 遥远的；偏僻的；细微的 bulb n. 鳞茎；球形物 Morse code 莫尔斯电码 pulse n. 脉搏；脉冲,1.2 Analog and Digital CircuitsNew Words and Expr
34、essions,buzzer n. 嗡嗡作声的东西；蜂鸣器；信号手 manipulate vt.（熟练地）操作； 利用；应付 destination n. 目的地；目的单元格 humidity n. 湿气；潮湿；湿度 interface n. 接触面；界面 comparator n. 比较仪 trigger vt.引起；触发 vi. 转移； n. 扳机 sequence n. 次序；顺序；序列 serial adj. 连续的；串行的；顺次 decoder n. 解码器 reassemble vt. 重新召集 vi. 重新集合,(1) Analog Analog quantities vary
35、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 recording thermometer, the actual equipment is shown in Fig. 1.6.,1.2 Analog and Digital CircuitsTEXT,Note：模拟系统通过在某一范
36、围内平滑而连续地变化的电信号反映模拟信息。,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.,1.2
37、 Analog and Digital CircuitsTEXT,Note：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F），并把温度随时间的变化曲线描绘在这张专用的方格纸上。,(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
38、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 CircuitsTEXT,Note：in the form of ：以.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。,The system shown in Fig.1.7 is a simplified version of
39、the original telegraph system, but it will demonstrate the principle and help to define a digital system.,1.2 Analog and Digital CircuitsTEXT,The 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 posit
40、ion 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 the information to be sent using the international Morse telegraph code.,1.2 Analog and Digital CircuitsTEXT,Note： is remotely lo
41、cated from （远离）,Note： transmitted from . to；从.传递到.；,Note： information to be sent ：要传递的信息,Morse 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 lett
42、ers and numbers into words sends the information.,1.2 Analog and Digital CircuitsTEXT,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。,The sender keeps the same shorter time interval b
43、etween 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 itself.,1.2 Analog and Digital CircuitsTEXT,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。,The T is one dash (one
44、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 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 tel
45、egraph, this person listened to a buzzer or “sounder” to identify the code.,1.2 Analog and Digital CircuitsTEXT, 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。,Coded patterns of changes from one state to another as time passes carry the information. At any insta
46、nt 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 important component of digital systems is the timing of signals.,1.2 Analog and Digital CircuitsTEXT,Note：随时间从一个状态变化到另一个状态的编码图携带信息。At any instant of time：任
47、何一个时刻,In many cases, digital signals, either at discrete levels, or changing between 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 th
48、e information being processed in a digital system.,1.2 Analog and Digital CircuitsTEXT,Note：通过系统时针电路来维持数字系统的计时。,Note：这就是在数字系统中识别被处理的数字信号和信息的方法。,(3) Quantities The temperature, pressure, humidity and wind velocity in our environment all change smoothly and continuously, and in many cases, slowly. Ins
49、truments that measure analog quantities usually have slow response and less 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 CircuitsTEXT,Note： 0.1% or 1 part in 1000 ：百分之零点一或千分之一。,Digital quantities, on the other hand, can be maintained at very high accuracy and measured 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.,
