电气工程及其自动化专业英语第一章翻译

第一章第一篇sectiongTwo variables u(t) and i(t) are the most basic concepts in an electric circuit, they characterize the various relationships in an electric circuitu(t)和i(t)这两个变量是电路中最基本的两个变量，它们刻划了电路的各种关系。

Charge and CurrentThe concept of electric charge is the underlying principle for explaining all electrical phenomena. Also, the most basic quantity in an electric circuit is the electric charge. Charge is an electrical property of the atomic particles of which matter consists, measured in coulombs (C). 电荷和电流电荷的概念是用来解释所有电气现象的基本概念。

也即，电路中最基本的量是电荷。

电荷是构成物质的原子微粒的电气属性，它是以库仑为单位来度量的。

We know from elementary physics that all matter is made of fundamental building blocks known as atoms and that each atom consists of electrons, protons, and neutrons. We also know that the charge e on an electron is negative and equal in magnitude to 1.60210×10 19C, while a proton carries a positive charge of the same magnitude as the electron. The presence of equal numbers of protons and electrons leaves an atom neutrally charged. 我们从基础物理得知一切物质是由被称为原子的基本构造部分组成的，并且每个原子是由电子，质子和中子组成的。

注：电气工程及其自动化专业英语翻译 1~7面班级：1002班学号：20姓名：王定瑞PART 1 FUNDAMENTALS OF ELECTRIC ENGINEERINGChapter 1 Circuit Fundamentals第1部分的电气工程基础第1章电路原理Electrostatic Charges静电荷Protons and electrons are parts of atoms that make up all things in our world. The positive charge of a proton is similar to the negative charge of an electron. However, a positive charge is the opposite of a negative charge. These charges are called electrostatic charges. Each charged particle is surrounded by an electrostatic field.质子和电子部件的原子构成一切事物在我们的世界。

正电荷的质子是类似于负电荷的电子。

然而,一个正电荷的反面是一个负电荷。

这些指控被称为静电荷。

每个带电粒子周围是一个静电场。

The effect that electrostatic charges have on each other is very important. They either repel (move away) or attract (come together) each other. It is said that like charges repel and unlike charges attract.这个效应,静电指控对方是非常重要的。

他们要么排斥(离开)或吸引(一起)每个其他。

电气自动化专业英语全文翻译第一部分:电子技术第一章电子测量仪表电子技术人员使用许多不同类型的测量仪器.一些工作需要精确测量面另一些工作只需粗略估计rough estimates.有些仪器被使用be used to仅仅solely是确定线路是否完整.最常用的测量测试仪表有:电压测试仪voltage testers,电压表voltmeters,欧姆表ammeters, ohmmeters 连续性测试仪continuity testers,兆欧表megohmmeters,瓦特表wattmeters还有瓦特小时表所有测量电值的表基本上都是电流表. 他们测量或是比较通过他们的电流值. 这些仪表可以被校准calibrate并且设计了不同的量程scale,以便to读出期望的数值.1.1 安全预防safety precaution仪表的正确连接对于使用者的安全预防和仪表的正确维护是非常重要的. 仪表的结构construction和操作的基本知识能帮助使用者按安全工作程序safe working order来对他们正确连接和维护.许多仪表被设计的只能用于直流或只能用于交流,而其它的则可交替使用interchangeably.注意:每种仪表只能用来测量符合设计要求的电流类型. 如果用在不正确的电流类型中可能对仪表有危险并且可能对使用者引起伤害.许多仪表被设计成are constructed to只能测量很低的数值,还有些能测量非常大的数值.警告: 仪表不允许超过它的额定rated最大值maximum limit. 不允许被测的实际数值超过exceed仪表最大允许值的要求再强调也不过分overemphasized.超过最大值对指针indicating needle有伤害,有害于interfere正确校准proper calibration,并且在某种情况下and in some instances 能引起仪表爆炸explode造成result in对作用者的伤害.许多仪表装备了are equippedwith过载保护over correct protection.然而,通常情况下电流大于仪表设计的限定仍然是危险的hazardous.1.2 基本仪表的结构和操作许多仪表是根据电磁相互作用electromagnetic interaction的原理动作的.这种相互作用是通过流过导体的电流引起的(导体放置在永久磁铁permanent magnet的磁极poles之间) .这种类型的仪表专门适合于is suit for直流电direct current.不管什么时候电流流过导体, 磁力magnetic force总会围绕导体形成is developed. 磁力是由在永久磁铁力的作用下起反应react的电流引起.这就引起指针的移动.导体可以制成线圈coil,放置在永久磁铁磁极之间的枢钮(pivot 中心)上.线圈通过两个螺旋型spiral弹簧springs连在仪器的端子上.这些弹簧提供了与偏差成正比proportional的恢复力deflection.当没有电流通过时,弹簧使指针回复到零.表的量程被设计来指明被测量的电流值.线圈的移动(或者是指针的偏移)与线圈的电流值成正比.如果必须要测量一个大于线圈能安全负载的电流,仪表要包含旁路bypass circuit 或者分流器shunt.分流器被容纳在仪表盒内或者连接到外部.例子一个仪表被设计成最大量程scale是10A.线圈能安全负载0.001A,那分流器必须被设计成能负载9.999A.当时.001A 流过线圈时指针指示10A.图1.1(A)说明了一个永久磁铁类型仪表.图1.1(B)显示了一个外部分流器连接到仪表端子上. 永久磁铁类型仪表可以被用作安培表或者电压表. 当量程被设计成指示电流并且内阻internal resistance保持最小时, 这个表可以作为安培表用. 当量程被设计成指示电压, 内阻相对relatively高一些时, 这个表可以用来测量电压值.注意:不管如何设计,指针移动的距离取决于线圈的电流值.为了让这类表用在交流电中,在设计时必须作微小的改动.整流器rectifier可以把交流变成直流电. 整流器合并incorporate进仪表中并且量程要指示出正确的交流电压值. 整流器类型的仪表不能用于直流电中并且它一般被设计成电压表.如图1.2,电测力计electrodynamometer是另一种能用于交流电alternating current的既能作安培表也能作电压表的仪器.它由两个固定线圈stationary coils和一个移动线圈movable coil构成consist of. 这三个线圈通过两个螺旋型spiral弹簧串联in series with在一起. 这个弹簧支撑住移动线圈.当电流流行性过线圈时移动线圈顺时针方向in clockwise direction移动.电测力计因为属永久磁铁型仪表it is in permanent magnet-type meters, 量程不是均匀分布的the scale is not divided uniformly. 作用在动线圈上的力根据流过该线圈的电流平方the square of the current flowing through the coil来变化vary with.有必要在量程开始比量程结束分割的密一点.分割点之间距离越大, 仪表的读数越精确.争取strive for 精确的读值an accurate reading是重要的.移动叶片moving-vane结构是仪表的另一种类型.电流流过线圈引起cause两个铁片iron stripes(叶片)磁化to become magnetized.一个叶片是可动的,另一个是固定的sationary.在两个叶片间的磁的作用引起可动叶片扭转turn.移动的数值取决于线圈的电流值.警告:所有描述的取决于磁力作用的仪器,都不要放置在另一个磁性物质附近.它的磁力可能对引起仪表故障或者导致测量值不准确.1.3 测量仪器的使用电压表a voltmeter是设计来is designed to测量measure电路applied a current的电压electrical pressure或者通过元器件across a component的压降voltage drop. 电压表必须与被测量的电路或元器件并联in parallel with.1.3.1 压力检验计(电压检测计)交-直流电压检验计是一种相当粗糙crude但对电工electrician来说很有用的仪器.这种仪器指示电压的近似值.更常见类型指示的电压值如下:AC,110,220,440,550V,DC,125,250,600V. 许多这种仪器也指示indicate直流电的极性polarity.那就是说(i.e=that is)电路中的导体是阳性positively(正)的还是阴性negatively(负) .电压检验计通常用来检验check公共电压common voltages,识别identify接地导体grounded conductor,检查to check for被炸毁的保险丝blown fuses,区分distinguish AC 和DC. 电压检验计很小很坚固rugged,比一般的电压表average voltmeter容易携带和保存.图1.31.4 描述了depict用电压检验计检查保险丝的用法methods.为了确定电路或系统中的导体接地, 把测试仪连接在导体和已建立的地之间. 如果测试仪指示了一个电压值,导体没有接地.对每一个导体重复这个步骤continue this procedure直到until零电压zero voltage出现is indicated(见图1.5) .为了确定任意两个导体间的近似电压值,把测试仪连接在导体之间.警告:要认真读并遵守电压检验计提供supplied的说明书instructions.1.3.2 电压表电压表比电压检验计测量更精确. 因为电压表与被测量的电路或元件并联, 必须有相对高一点的电阻. 内阻要保证通过仪表的电流最小. 流过仪表的电流越小, 对电路特性electrical characteristics的影响effect越小.仪表的灵敏度sensitivity用符号O/V 表示is stated.这个数值越高仪表的质量越好.高灵敏度可使电路特性的改变减到最小.电工使用的仪表精确度在95%到98%之间.这个精确度范围对大多数应用是满意的.然而, 电力工作者力求strive to obtain最精确的可能读数是重要的. 一个精确读数可以在仪表盘上显示standing directly in front of the meter face也可以直接读出来.如果在指针后面有镜子,调整视线的角度直到指针在镜子中看不到映象.如要更精确可以使用数字表.电压表有与电压检验计同样的应用. 电压表比电压检验计更精确. 因而, 也支持更多的应用. 例如,如果一个建筑物的供电电压低于正常值slightly below normal,电压表能指示出这个问题.电压表也用来确定馈电线on feeder和支线电路导体branch circuit conductors的压降值voltage drop.电压表有时有不只一个量程. 选择一个能更精确测量的量程很重要. 选择器开关范围达到这个目的.注意:开始用一个适当的高一点的量程,然后逐渐降低到在限定范围之内的最低量程.设定选择器开关在可用的最低量程上能使读数达到最精确.使用仪表之前,要检查仪表确保指针指在零上.在仪表盘下面有一个调整螺钉an adjustment screw.一个轻微的扭动就能使指针偏移.扭转调整螺钉使指针对准零线.当在DC 中使用电压表时,保持maintain正确proper的极性是很重要的.大多数的直流电源和仪表都用颜色标记color coded极性polarity.红色指示阳极,黑色指示阴极.如果电路和元件的极性未知,触一下端子的导线leads观察observing指针indicating needle.如果指针犹豫着试图attempts to摆动,仪表导线连接就要颠倒一下be reversed.警告:不要让仪表连接反的极性polarity reversed.1.3.3 安培表安培表是用来测量电路或部分电路的电流数量的. 他与被测电路元件串联连接. 仪表的电阻必须非常低这样不会影响restrict流过电路的电流. 当测量很灵敏的设备的电流, 安培表电流的轻微改变可能会引起设备的故障.安培表象电压表一样, 也有一个调零的调整螺钉. 许多仪表也有镜子帮助assist使用者保证读数精确in obtaining an accurate reading.安培表常用来找出过载或者开路.他们也用来平衡线路的负荷loads on multiwire circuits 和确定故障位置malfunctions.安培表总是与被测电路或元件串联连接.如果使用在DC 下要检查极性.图 1.6(A)显示了安培表测量电路的电流.图 1.6(B)显示的是AC 安培表.Chap2 固体功率器件的基本原理2.1 引言(绪论) 本章将集中讨论固态功率器件或功率半导体器件,并且只研究它们在采用相控(电压控制) 或频率控制(速度控制)的三相交流鼠笼式感应电机的功率电路中的应用.2.2 固态功率器件有五种用于固体交流电机控制中的功率元器件: (1) 二极管(2) 晶闸管(例如:可控硅整流器SCR) (3) 电子晶体管(4) 门极可关断晶闸管(GTO) (5) 双向可控硅晶闸管SCR 和双向可控硅一般用于相位控制(相控) .各种二极管,晶闸管SCR,电子晶体管,门极可关断晶闸管的联合体用于频控.这些器件的共性是:利用硅晶体形成的薄片构成P-N 结的各种组合.对二极管,SCR, GTO 一般P 结叫正极N 结叫负极;相应的电子晶体管叫集电极和发射极.这些器件的区别在于导通和关断的方法及电流和电压的容量. 让我们根据他们的参数简单看一下这些元器件. 2.2.1 二极管图 2.1 显示了一个二极管,左边部分显示的是在硅晶体中的一个PN 结,右边显示的是二极管的原理图符号. 当P 相对于N 是正时,由于节上有一个相当低的压降,前向电流开始流动.当极性相反时, 只有一个极小的反向漏电流流动.这些用图 2.2 阐明.前向电压通常大约有1V,不受电流额定值的影响. 二极管正向导通电流的额定值取决于其尺寸和设计, 而这二者是根据器件散热的要求来确定的,以保证器件不超过最大结温(通常为200C) . 反向击穿电压是二极管的另一个重要参数. 它的值更取决于二极管的内部设计而不是它的物理尺寸. 注意:一个二极管只有当加上正向电压时才会正向导通.它没有任何固有(内在的)的方法控制导通的电流和电压值. 二极管主要用在交流电路中作整流器,这意味着它们把AC 整流成DC,同时产生的直流电流和电压值没有固有的控制方法.单二极管可用额定值到4800A 和最大反向电压1200V, 2000A 最大反向电压4400V. 2.2.2 晶闸管图 2.3 显示了晶闸管(一般也叫可控硅)的PN 结排列和它的原理图符号.注意这不同的结从正到负是PNPN,还有一个门极连到了内部的P 层. 如果没有连门极,并且阳极加反向电压,从正极到负极就没有电流通过.这是因为内部P 结由于未通电而工作在阻断电路.这种情况对于正向阻断状态也是正确的.然而,当阳极是正的并且正信号作用到门上,则电流将从正极一直流向负极即使门极没有正信号. 换言之, 门极能打开晶闸管但不能关断它. 关断晶闸管的唯一方法是通过外部方式在正极强加上一个零电流. 因此在前向导通只能通过强加零电流停止方面, 晶闸管与二极管是相似的.然而,晶闸管与二极管在如何启动前向导通方面是不同的. (1)阳极是正(2)门时刻是正.这个特性暗指了术语"可控硅" . 图 2.4 阐明了晶闸管的稳态伏安特性.注意反向电压和反向泄漏电流的形状与二极管的很相似.反向电压导通时比二极管的高,通常有 1.4V.阻断状态也有一个极小的前向泄漏电流. 在二极管中,稳态电流值是由器件的性能和底座(散热器)散发的热量确定的.晶闸管的最大结温比二极管要低,大约在125C.这意味着在同样的额定电流下,加上 1.4V 的前向压降,晶闸管比二极管的前向压降大的多.单晶闸管可用额定值在最大反向电压2200V 超过2000A,在在最大反向电压4000V 超过1400A. 2.2.3 电子晶体管(电子管) 图2.5 列出了一个典型功率电子管的结排列,原理符号图和伏安特性.如果集电极为正, 除非在基电极和发射极间有电流才有电流从集电极到发射极. 与晶闸管比较, 只有在基极有电流时, 电子管没有从集电极到发射极的自锁电流. 基极开路, 集电极到发射极将阻断电流. 功率电子管与晶闸管在控制前向导通的启动时相似. 它与晶闸管不同的地方在于它能控制关断和交流电机频率控制所必需的换向. 注意伏安特性没有显示反向特性.一般的,一个反向分流二极管连在发射极和集电极之间, 以保护电子管受反向电压伤害.功率电子管的可用额定值是最高反向电压1000V400A. 2.2.4 门极可关断晶闸管GTO 图 2.6 显示了GTO 的原理符号.GTO 与晶闸管的相似处在于PNPN 结的排列和前向电流的操作.如果阳极是正的,导体的启动是通过作用在门上的正脉冲.然而硅片和结是利用特殊特性设计的,所以即使阳极保持正值,加到门上的强负电流作用迫使前向电流阻断.GTO 常用的瞬间额定值是PRV1200V2400A.2.2.5 双向可控硅图2.7 显示了双向可控硅的原理符号图.一个双向可控硅由一个特殊的晶闸管包(包含前向和反向晶闸管)组成,它的操作由一个门极控制.他们常用在调光器电路中或者作为继电器的开关, 这样截止态下很小的泄漏电流不会引起其它控制器的误操作. 随着增加电流容量可控硅的可用性使他们用于交流电机的相位控制中. 2.3 功率半导体容量功率器件在稳态交流电机马力范围大于600V 时如何用,用在哪里摘要显示在表 2.1 中. 马力额定值基于没有并联的器件. 2.4 功率半导体的物理特性在物理特性条件下,有三类最常用的功率半导体: (1)栓接式(2)薄片或冰球式(3)绝缘散热器类型.他们的共同特征是需要与其它器件有物理联系.这器件叫散热器,为了保持结温在设计值内把内部热量散发出去.散热器吸收结的热量通过散热片,轮片(螺旋桨叶片) 或者液体冷却剂发散出去.液体冷却剂几乎从不用于600V 级的固态交流电动机控制中,而且也不包含在我们的讨论中. 这三类功率半导体的不同在于它们如何安装, 他们如何与散热器连接. 2.4.1 栓接式螺纹部分可能是PN 结的一部分,或者是与有源电子部分电子绝缘.在任一种情况下,螺纹部分常常插入散热器的螺纹孔. 栓接式器件在小马力额定值下常用来作为直接功率控制器件, 在大马力额定值下常用来作为辅助保护器件.在后一种情况下,它们常直接安装在较大器件使用的散热器上,如冰球式设计. 2.4.2 冰球式器件典型冰球式功率器件可能是二极管, 可控硅或GTO. 尺寸范围直径从近似25MM 到100MM. 每一个平坦的面即不是P 也不是N 结.热传递和导电从这表面产生.冰球式器件典型安装是联接铝型材的散热器.特别的箝位电路,联接绝缘混合剂和扭矩扳手都是需要的,用来确定光热传递和电导率. 由于栓接式和冰球式器件的散热器都能传递电流, 他们必须与机械底托电子绝缘. 轮片能加到散热器上增加热量排放并且增大固定负荷状态的完成. 由于散热器能在同样电压水平下作为功率器件, 冰球式和栓接式的固态AC 电动机控制必须通过附件(外壳)供给.附件(外壳)必须有合适的通风口或热交换器使得热量能散发.它不会用在放在安全封套中的用法,例如象NEMA12 的密封盒或相似的外围物. 2.4.3 绝缘散热器件绝缘散热器功率器件可能是二极管,可控硅,GTO,三极管或双向可控硅.单个的包包含器件的联合体,在内部以线加固.区别的特征是术语"绝缘散热器" .有一个铝底盘在每个包下面.这个底板与功率器件之间是导热并绝缘的.结的大部分热量传给了铝盘.这个底板依次安装在第二个更大的散热底板上.这个更大的散热底板在对面有鳍状表面. 绝缘散热器的设计使它自己是个完全封闭的设计. 他们也有经过预包装的已经内部加固过的复合器件的优点. 他们的缺点是通过底部安装的底板散热的能力有限, 所以固定负荷状态必须小于开放的散热器—安装在冰球式器件上. 尽管如此, 绝缘散热器在一般应用和器件容量的使用上迅速增长. 在较高的左上角的排列是唯一的, 同样它联合了有所有封闭设计的绝缘散热器概念的冰球式的优点(例如,易替换,易互换) .它也被恰当的称为"开放块状"模式. 2.5 换流在深入的讨论实际的固态交流电机的控制之前, 将换流的概念和种类阐述清楚是必要的. 换流的不同类型指所有讨论的固态电动机控制. 换流是功率半导体器件中负载电流被截止或停止流动或转换到另一回路的过程. 有以下三种换流方式: (1)自然或线电压换流(2)负载换流和(3)强制换流. 2.5.1 自然或线换流图 2.8 显示了功率半导体电路把AC 转换成DC.这个列举chap 3 模拟电子3.1 介绍3.1.1 模拟和数字电子的对比我们已经研究了晶体管和二极管作为开关设备怎样处理被以数字形式描述的信息(数字信息) .数字电子象用电力控制开关那样使用晶体管: 晶体管被饱和或者切断.动态区域只是从一个状态到另一个状态的过渡. 对比起来, 模拟电子取决于晶体管和其他类型放大器的动态区域. 希腊词根"analog" 意味着" 以一定的比例" ,在这里表示信息被编码成与被描述的量(被表达量) 成正比的电信号. 在图 3.1 中我们的信息是某种音乐,是乐器的激励和回响自然发起(引起) .被传播出的声音在于空气分子的有规则的运动并且被最好作为声波理解. 在话筒(扩音器)的振动膜里的这些产生的运动,依次产生一个电信号.电信号的变化与声波成比例(在电信号方面的变化是声波的成比例表现) .电信号被通过电子放大,即利用输入放大器的交流电能将信号的功率放大. 放大器的输出驱动一个录音磁头并且在磁盘上产生波浪状的槽沟. 如果整个系统是好的,空气的一切声变将被记录在磁盘上,当记录被通过一个相似的系统播放时,信号通过一个扬声器作为声音能量再传播出来,结果原始音乐被如实的再现了. 基于模拟原则的电子系统形成一类重要的电子仪器. 收音机和电视的广播是模拟系统的典型例子,许多电子仪器也是模拟系统,它们的应用包括偏差检测(应变计量器) ,运动控制(测速机)和温度测量(热电耦) .许多电子仪器---电压表,欧姆表,安培表和示波器利用了模拟技术,至少部分利用了模拟技术. 在数字电子计算机被发展之前,模拟计算机一直使用.在模拟计算机中,微分方程里的未知量被用电信号来模拟. 这些信号被用电子的方法积分,比例变换和求和以获得方程的解,比起解析或数值运算的求解方法要容易一些. 3.1.2 本章的主要内容模拟技术广泛地运用频域的观点.我们首先扩大我们的频域的概念包括周期,非周期和随机信号. 我们将看到大多数模拟信号和过程可以被表示为频域. 我们将介绍频谱的概念, 也就是,用同时存在的很多频率来表达一个信号.带宽(频宽)(频谱的宽度) 在频域上将与时间域上的信息率有关. 频域的这个被阐述的概念也帮助我们区分线和非线性的模拟设备的影响. 线性电路被显示有"滤波器" 的能力而不需要频率组件.对比起来,新频率可以被象二极管和晶体管那样的非线性的设备产生.这种性能允许我们通过调幅和调频调制技术在频域上转换模拟信号, 这种调制技术已被公开广泛地使用公用和私人通信系统. 作为一个例子我们将描述一台调幅收音机的操作. 下面我们研究一下反馈的概念, 在模拟系统中通过反馈可以交换到象线性或者更宽的带宽那样合乎需要的质量. 如果没有反馈, 象音频放大器或者电视接收机那样的模拟系统最多提供了一个糟糕的性能. 理解反馈的好处可以提供正确评价模拟电子中运算放大器的很多用途的基础(提高对模拟电子中运算放大器的很多用途的认识) . 运算放大器(简写OP amps) 是模拟电路的基本组成部分,正如NOR 或非和NAND 与非门电路是数字电路的基本单元一样. 我们将介绍一些运算放大器一般应用, 以在模拟计算机里的他们的用途来结束. 3.2 运算放大器电路3.2.1 介绍(1) 运算放大器的重要性.运算放大器是一个在受负反馈控制的高增益的电子放大器,用来在模拟电路中完成很多运算功能.这样的放大器最初被发展完成运算,例如在模拟计算机里为微分方程的求解的积分和求和. 运算放大器的应用被增加了, 直到目前为止, 大多数模拟电子电路基于运算放大器技术.例如,你需要一个放大器获得10 倍的增益,便利, 可靠性, 费用考虑将确定使用一个运算放大器. 因此, 运算放大器形成模拟电路的基本构件, 正如NOR 或非和NAND 与非门电路是数字电路的基本单元一样. (2) 运算放大器模型典型的特性.典型的运算放大器是利用十多个晶体管,几个二极管和很多电阻器的一个复杂的晶体管放大器. 这样的放大器被在半导体芯片上批量生产并且售价少于 1 美元一个.这些部件是可靠,耐用的,并且在他们的电子特性接近理想. 图 3.2 显示一台运算放大器的基本特性和符号.有两个输入电压u+和u _ ,用大的电压增益差分放大, 通常达105 - 106. 输入电阻R 也很大, K -100 M 欧. 100 输出电阻Ro 很小, 10-100 欧. 放大器经常用正极(+ Ucc) 和负极(-Ucc) 电源提供直流电源. 对这个情况来说,输出电压在供电电压之间,- Ucc<Uo<+ Ucc. 有时一个电源接地( 即,"-Ucc" =0). 这样的话输出电压在0<Uo<+ Ucc 之间.电源连接很少被画进电路图,可以认为运算放大器和合适的电源连结起来.因此运算放大器接近一个理想的电压放大器,有高的输入电阻,低的输出抵抗和高的增益. 高增益通过使用强大的负反馈变为其他有用的特征.负反馈的全部好处被运算放大器电路利用了. 对那些早在这章里列举, 我们将为运算放大器电路还增加 3 个好处: 低扩张性, 便于设计,和简单的构造. (3) 这节的内容.我们首先分析两个普通运算放大器应用,反相和同相放大器.我们通过一个简单而有效对任何运算放大器电路使用的一种方法,推导出这些放大器的增益. 我们然后讨论有源滤波器.这是有(带了)增加了频率响应的电容器的运算放大器.然后我们简单讨论模拟计算机,以讨论运算放大器的一些非线性的应用来结束. 3.2.2 运算放大器(1) 反相放大器. 反相放大器,用图 3.3 显示,使用一个运算放大器和两个电阻. 运算放大器的输入是地(零信号) ; 负(-) 电源连接输入信号(通过Ri) 并且(通过RF) 反馈到输出信号.在下列讨论中容易混淆的是我们必须同时谈到两个放大器.运算放大器是在负反馈放大器里形成放大要素的一种放大器, 负反馈放大器包含运算放大器加上相关电阻. 为了减少混乱,我们保留术语" 放大器" 只用在反馈放大器的总体上.运算放大器绝不是一个放大器;而被叫为运算放大器.例如,如果我们对放大器提及输入电流,我们指通过R1 的电流,并非进运算放大器的电流. 我们在图里能求出 3.3 反相放大器的增益,通过求解基本的电路法则(KCL 和KVL) 或者通过试图把电路分成主要放大器和反馈系统模块.不过,我们将提出另一方法,这种方法基于运算放大器增益很高,接近无限.在如下内容里,我们将给一般的假设,这可提供给任何运算放大器电路;然后我们将把特定假设用于目前的电路.因此,我们将建立反相放大器的增益和输入电阻. (1) 我们假定输出表现良好不试图达到无限.因此我们假定负反馈使放大器稳定, 因此适度的输入电压产生适度的输出电压.如果电源是+ 10 和-10 V,例如,那些输出必须位于这些有限值之间. (2)因此,运算放大器的输入电压非常小,基本上零,因为它是输出电压除以运算放大器的大的电压增益U+-U _ =0 = 》U+= U _ 例如,如果lUol<10 V 并且A= l05, 然后我u+ u _ l<10 /lOs = 100 UV. 因此对任何运算放大器电路通常u + 和u _ 在100 uV 或更少内相等. 对在图3.3 的反相放大器来说, u+接地; 因此,u _ =0. 从而,放大器的输入电流将为Ui-u _ Ui 见(3.1) il = Ri ~ R 1 (3) 因为u+=u _ 并且Ri 很大,进入放大器的+极和-极的运算放大器的输入电流将非常小,基本上零见(3.2) 例如, Ri = 100 k, {i _ }<10-4 /lOs = 10-9 A. 对于反相放大器,公式(3.2) 暗示输入端的电流I 流过RF, 如图。

电气工程及其自动化专业英语翻译（精选多篇）第一篇：电气工程及其自动化专业英语翻译Electric Power Systems.The modern society depends on the electricity supply more heavily than ever before.It can not be imagined what the world should be if the electricity supply were interrupted all over the world.Electric power systems(or electric energy systems), providing electricity to the modern society, have become indispensable components of the industrial world.The first complete electric power system(comprising a generator, cable, fuse, meter, and loads)was built by Thomas Edison – the historic Pearl Street Station in New York City which began operation in September 1882.This was a DC system consisting of a steam-engine-driven DC generator supplying power to 59 customers within an area roughly 1.5 km in radius.The load, which consisted entirely of incandescent lamps, was supplied at 110 V through an underground cable system..Within a few years similar systems were in operation in most large cities throughout the world.With the development of motors by Frank Sprague in 1884, motor loads were added to such systems.This was the beginning of what would develop into one of the largest industries in the world.In spite of the initial widespread use of DC systems, they were almost completely superseded by AC systems.By 1886, the limitations of DC systems were becoming increasingly apparent.They could deliver power only a short distance from generators.To keep transmission power losses(I 2 R)and voltage drops to acceptable levels, voltage levels had to be high for long-distance power transmission.Such high voltages were not acceptable for generation and consumption of power;therefore, a convenient means for voltage transformationbecame a necessity.The development of the transformer and AC transmission by L.Gaulard and JD Gibbs of Paris, France, led to AC electric power systems.In 1889, the first AC transmission line in North America was put into operation in Oregon between Willamette Falls and Portland.It was a single-phase line transmitting power at 4,000 V over a distance of 21 km.With the development of polyphase systems by Nikola Tesla, the AC system became even more attractive.By 1888, Tesla held several patents on AC motors, generators, transformers, and transmission systems.Westinghouse bought the patents to these early inventions, and they formed the basis of the present-day AC systems.In the 1890s, there was considerable controversy over whether the electric utility industry should be standardized on DC or AC.By the turn of the century, the AC system had won out over the DC system for the following reasons:（1）Voltage levels can be easily transformed in AC systems, thusproviding the flexibility for use of different voltages for generation, transmission, and consumption.（2）AC generators are much simpler than DC generators.（3）AC motors are much simpler and cheaper than DC motors.The first three-phase line in North America went into operation in 1893——a 2,300 V, 12 km line in southern California.In the early period of AC power transmission, frequency was not standardized.This poses a problem for interconnection.Eventually 60 Hz was adopted as standard in North America, although 50 Hz was used in many other countries.The increasing need for transmitting large amounts of power over longer distance created an incentive to use progressively high voltage levels.To avoid the proliferation of anunlimited number of voltages, the industry has standardized voltage levels.In USA, the standards are 115, 138, 161, and 230 kV for the high voltage(HV)class, and 345, 500 and 765 kV for the extra-high voltage(EHV)class.In China, the voltage levels in use are 10, 35, 110 for HV class, and 220, 330(only in Northwest China)and500 kVforEHVclass.Thefirst750kVtransmission line will be built in the near future in Northwest China.With the development of the AC/DC converting equipment, high voltage DC(HVDC)transmission systems have become more attractive and economical in special situations.The HVDC transmission can be used for transmission of large blocks of power over long distance, and providing an asynchronous link between systems where AC interconnection would be impractical because of system stability consideration or because nominal frequencies of the systems are different.The basic requirement to a power system is to provide an uninterrupted energy supply to customers with acceptable voltages and frequency.Because electricity can not be massively stored under a simple and economic way, the production and consumption of electricity must be done simultaneously.A fault or misoperation in any stages of a power system may possibly result in interruption of electricity supply to the customers.Therefore, a normal continuous operation of the power system to provide a reliable power supply to the customers is of paramount importance.Power system stability may be broadly defined as the property of a power system that enables it to remain in a state of operating equilibrium under normal operating conditions and to regain an acceptable state of equilibrium after being subjected to a disturbance..Instability in a power system may be manifested in many different ways depending on the system configurationand operating mode.Traditionally, the stability problem has been one of maintaining synchronous operation.Since power systems rely on synchronous machines for generation of electrical power, a necessary condition for satisfactory system operation is that all synchronous machines remain in synchronism or, colloquially “in step”.This asp ect of stability is influenced by the dynamics of generator rotor angles and power-angle relationships, and then referred to “ rotor angle stability ”译文：电力系统现代社会比以往任何时候更多地依赖于电力供应。

Electric Power Systems.The modern society depends on the electricity supply more heavily than ever before. It can not be imagined what the world should be if the electricity supply were interrupted all over the world. Electric power systems (or electric energy systems), providing electricity to the modern society, have become indispensable components of the industrial world. The first complete electric power system (comprising a generator, cable, fuse, meter, and loads) was built by Thomas Edison – the historic Pearl Street Station in New York City which began operation in September 1882. This was a DC system consisting of a steam-engine-driven DC generator supplying power to 59 customers within an area roughly 1.5 km in radius. The load, which consisted entirely of incandescent lamps, was supplied at 110 V through an underground cable system.. Within a few years similar systems were in operation in most large cities throughout the world. With the development of motors by Frank Sprague in 1884, motor loads were added to such systems. This was the beginning of what would develop into one of the largest industries in the world. In spite of the initial widespread use of DC systems, they were almost completely superseded by AC systems. By 1886, the limitations of DC systems were becoming increasingly apparent. They could deliver power only a short distance from generators.To keep transmission power losses ( I 2 R ) and voltage drops to acceptable levels, voltage levels had to be high for long-distance power transmission. Such high voltages were not acceptable for generation and consumption of power; therefore, a convenient means for voltage transformation became a necessity.The development of the transformer and AC transmission by L. Gaulard and JD Gibbs of Paris, France, led to AC electric power systems. In 1889, the first AC transmission line in North America was put into operation in Oregon between Willamette Falls and Portland. It was a single-phase line transmitting power at 4,000 V over a distance of 21 km. With the development of polyphase systems by Nikola Tesla, the AC system became even more attractive. By 1888, Tesla held several patents on AC motors, generators, transformers, and transmission systems. Westinghouse bought the patents to these early inventions, and they formed the basis of the present-day AC systems. In the 1890s, there was considerable controversy over whether the electric utility industry should be standardized on DC or AC. By the turn of the century, the AC system had won out over the DC system for the following reasons:（1）Voltage levels can be easily transformed in AC systems, thus providing the flexibility for use of different voltages for generation, transmission, and consumption.（2）AC generators are much simpler than DC generators.（3）AC motors are much simpler and cheaper than DC motors.The first three-phase line in North America went into operation in 1893——a 2,300 V, 12 km line in southern California. In the early period of AC power transmission, frequency was not standardized. This poses a problem for interconnection. Eventually 60 Hz was adopted as standard in North America, although 50 Hz was used in many other countries. The increasing need for transmitting large amounts of power over longer distance created an incentive to use progressively high voltage levels. To avoid the proliferation of an unlimited number of voltages, the industry has standardized voltage levels. In USA, the standards are 115, 138, 161, and 230 kV for the high voltage (HV) class, and 345, 500 and 765 kV for the extra-high voltage (EHV) class. In China, the voltage levels in use are 10, 35, 110 for HV class, and 220, 330 (only in Northwest China) and 500 kV for EHV class . The first 750 kVtransmission line will be built in the near future in Northwest China. With the development of the AC/DC converting equipment, high voltage DC (HVDC) transmission systems have become more attractive and economical in special situations. The HVDC transmission can be used for transmission of large blocks of power over long distance, and providing an asynchronous link between systems where AC interconnection would be impractical because of system stability consideration or because nominal frequencies of the systems are different. The basic requirement to a power system is to provide an uninterrupted energy supply to customers with acceptable voltages and frequency. Because electricity can not be massively stored under a simple and economic way, the production and consumption of electricity must be done simultaneously. A fault or misoperation in any stages of a power system may possibly result in interruption of electricity supply to the customers. Therefore, a normal continuous operation of the power system to provide a reliable power supply to the customers is of paramount importance. Power system stability may be broadly defined as the property of a power system that enables it to remain in a state of operating equilibrium under normal operating conditions and to regain an acceptable state of equilibrium after being subjected to a disturbance.. Instability in a power system may be manifested in many different ways depending on the system configuration and operating mode. Traditionally, the stability problem has been one of maintaining synchronous operation. Since power systems rely on synchronous machines for generation of electrical power, a necessary condition for satisfactory system operation is that all synchronous machines remain in synchronism or, colloquially "in step". This aspect of stability is influenced by the dynamics of generator rotor angles and power-angle relationships, and then referred to " rotor angle stability "。

1```In the generator mode ,it,s operating speed isslightly higger than it,s synchronous speed and ie needs magnetizing revctive pover form the symtem that it is connected to in order to suuply pover .在发电方式下他的工作速度比同步转速稍高些，并了解供电力，他需要他所连接的系统吸收磁化无功功率。

2```in the barking mode of operyetion ,a three –phase indection motor running at a steady –speedcan be brought to a quick stop by interchanging two of stator leads感应电机运行电动状态时，其转速低于同步转速，运行在发电状态时，其转速高于同步转速，这就需要从与之间相连的系统电源提供励磁的无功功率。

3```obviously ,dc machine applications are very significant,but the advantages of the dc machinemmust be weighed against its greatr initial investment cost and the maintenance problems associated with its brush-commutator system..同步是指状态运行时点击以恒定的转速和频率运行。

4```with a cylindyical rotor the reluctance of the magnetic circuit of the field is independent of itsactual diretion and relative to the direct axis.圆柱形转子的磁场磁路的磁阻与直轴有关，而与磁场的实际方向无关。

电气工程及其自动化专业英语翻译Last revision on 21 December 2020Semiconductor switches are very important and crucial components in power electronic switches are meant to be the substitutions of the mechanical switches,but they are severely limited by the properties of the semiconductor materials and process of manufacturing. 在电力电子系统，中半导体开关是非常重要和关键部件。

半导体开关将要替换机械开关,但半导体材料的性质和生产过程严重限制了他们。

Switching losses开关损耗Power losses in the power eletronic converters are comprised of the Switching losses and parasitic losses. 电力电子转换器的功率损耗分为开关损耗和寄生损耗the parasitic losses account for the losses due to the winding resistances of the inductors and transformers,the dielectric losses of capacitors,the eddy and the hysteresis losses. 寄生损失的绕组电感器、变压器的阻力、介电损耗的电容器,涡流和磁滞损耗the switching losses are significant and can be managed. 这个开关损耗是非常重要的,可以被处理。

Semiconductor switches are very important and crucial components inpower electronic systems.these switches are meant to be the substitutionsof the mechanical switches,but they are severely limited by the properties of the semiconductor materials and process of manufacturing.在电力电子系统，中半导体开关是特别重要和重点零件。

半导体开关将要替代机械开关,但半导体资料的性质和生产过程严重限制了他们。

Switching losses开关消耗Power losses in the power eletronic converters are comprised of the Switching losses and parasitic losses.电力电子变换器的功率消耗分为开关消耗和寄生消耗the parasitic losses account for the losses due to the winding resistances of the inductors and transformers,the dielectric losses ofcapacitors,the eddy and the hysteresis losses.寄生损失的绕组电感器、变压器的阻力、介电消耗的电容器, 涡流和磁滞消耗the switching losses are significant and can be managed.这个开关消耗是特别重要的, 能够被办理。

they can be further divided into three components:(a)the on-state losses,(b)the off-state losses and the losses in the transition states.他们能够分为三个部分:通态消耗，断态消耗和转换过程中产生的消耗。

电气工程及其自动化专业英语Section I basic electric circuitChapter 1 Introduction to electric circuitsNew Words and Expressions1. electrical circuit n. 电路2. voltage n. 电压，伏特3. curre nt n. 电流，通用的，流通的，现在的4. curre nt flow n. 电流5. resistor n. 电阻，电阻器6. battery n. 电池7. load n. 负载，负荷8. performa nee n. 性能9. circuit diagram n. 电路图10. idealized model n. 理想模型Introduction*A simple circuit and its components.idealized model of the circuit*Model can be cha nged if n ecessary.*summarizeIn elementary physics classes you undoubtedly have been introduced to the fun dame ntal con cepts of electricity and how real comp onen ts can be put together to form an electrical circuit. A very simple circuit, for example, might consist of a battery, some wire, a switch, and an incandescent light bulb as shown in Fig.1-1. The battery supplies the en ergy required to force electro ns around the loop, heati ng the filame nt of the bulb and caus ing the bulb to radiate a lot of heat and some light.Energy is transferred from a source, the battery, to a load, the bulb———You probably already know that the voltage of the battery and the electrical resista nee of the bulb have something to do with the amount of curre nt that will flowin the circuit. From your own practical experienee you also know that no current will flow until the switch is closed. That is, for a circuit to do anything, the loop has to be completed so that electro ns can flow from the battery to the bulb and the n back aga in to the battery. And fin ally, you probably realize that it doesn t much matter, whether there is on e foot or two feet of wire connecting the battery to the bulb, but that it probably would matter if there is a mile of wire between it and the bulb.Also shown in Fig. 1-1 is a model made up of idealized components. The batteryis modeled as an ideal source that puts out a constant voltage, VB, no matter what amount of curre nt, i, is draw n. The wires are con sidered to be perfect con ductors that offer no resista nee to curre nt flow. The switch is assumed to be ope n or closed. There is no arcing of curre nt across the gap whe n the switch is ope ned, nor is there any bounce to the switch as it makes con tact on closure. The light bulb is modeled as a simple resistor, R, that never changes its value, no matter how hot it becomes or how much curre nt is flow ing through it.Fig. 1-1 (a) A simple circuit(b) An idealized represe ntati on of thecircuitFor most purposes, the idealized model shown in Fig. 1-1b is an adequate represe ntati on of the circuit; that is, our prediction of the current that will flow through the bulb whenever the switch is closed will be sufficiently accurate that we can consider the problem solved. There may be times, however, when the model is in adequate. The battery voltage, for example, may drop as more and more curre nt is drawn, or as the battery ages. --------------------------------- T he light bulb' s resistance may change as it heats up, and the filame nt may have a bit of inductance and capacitance associated with it as well as resistance so that when the switch is closed, the current may not jump in sta ntan eously from zero to some fin al, steady state value. The wires may beundersized, and some of the power delivered by the battery may be lost in the wires before it reaches the load. These subtle effects may or may not be important, depending on what we are trying to find out and how accurately we must be able to predict the performa nee of the circuit. If we decide they are importa nt, we can always cha nge the model as n ecessary and then proceed with the an alysis. The point here is simple. The comb in ati ons of resistors, capacitors, in ductors, voltage sources, curre nt sources, and so forth, that you see in a circuit diagram are merely models of real comp onents that comprise a real circuit, and a certa in amount of judgme nt is required to decide how complicated the model must be before sufficie ntly accurate results can be obta in ed. For our purposes, we will be using very simple models in general, leav ing many of the complicati ons to more adva need textbooks.Chapter 2Definitions of key electrical quantitiesNew Words and Expressionscharge n. vt.电荷；充电nu cleus n.原子核(pl.); nuclear adj.n egative n.否定，负数，底片adj.否定的，消极的，负的，阴性的positive adj.［数］正的adj.［电］阳的in gen eral 通常,大体上，一般而言，总的说来algebraic adj.代数的，关于代数学的soluti on to the circuit problem n.关于电路问题的解法the un its of power n.功率的单位direct curre nt (dc) n 直流电alter nat ing curre nt(ac) n.交流电sinu soidally adv.正弦地tran sistor n.晶体管Part 1 Charge and CurrentAn atom con sists of a positively charged nu cleus surro un ded by a swarm of n egativelycharged electr ons. The charge associated with one electr on has bee n found to be 1.602 x 10- 19 coulombs; or, stated the other way around, one coulomb can be defined as the charge on 6.242 x 1018 electro ns. While most of the electr ons associated with an atom are tightly bound to the nu cleus, good con ductors, like copper, have free electrons that are sufficie ntly dista nt from their nu clei that their attract ion to any particular n ucleus is easily overcome. These con ducti on electr ons are free to wan der from atom to atom, and their moveme nt con stitutes an electric curre nt.In a wire, when one coulomb ' s worth of charge passes a given spot in one second, the current is defined to be one ampere (abbreviated A), named after the nineteenth-century physicist Andr ' e Marie Amp'ere. That is, curre nt i is the net rate of flow of charge q past a point, or through an area:i=d q/d t (1.1)In general, charges can be negative or positive. For example, in a neon light, positive ions move in one direct ion and n egative electr ons move in the other. Each con tributes to curre nt, and the total curre nt is their sum. By conven ti on, the direct ion of curre nt flow is take n to be the direct ion that positive charges would move, whether or not positive charges happen to be in the picture. Thus, in a wire, electrons moving to the right constitute a current that flows to the left, as shown in Fig.1-2.(〉)dq--- / =—dtFig. 1-2 By conven tio n, n egative charges movi ng in one direct ion con stitute a positive curre ntflow in the opposite direct ionW/hen charge flows at a steady rate in one direction only, the current is said to be direct current, or 血A battery, for example, supplies direct curre nt. When charge flows back and forth sinusoidally, it is said to be alternating current, or ac. In the United States the ac electricity delivered by tes of ac and dc are show n in Fig.1-3.Time ―(a)Fig. 1-3 (a) Steady-state direct curre nt (de) (b) Alter nat ing curre nt(ac)Part 2 Kirchhoff' s Current LawTwo of the most fun dame ntal properties of circuits were established experime ntally a cen tury and a half ago by a Germa n professor, Gustav Robert Kirchhoff (1824 - 1887). The first property, known as Kirchhoff ' s current law (abbreviated KCL), states that at every instant of time the sum of the curre nts flow ing into any node of a circuit must equal the sum of the curre nts leavi ng the no de, where a node is any spot where two or more wires are join ed. This is a very simple, but powerful con cept. It is in tuitively obvious once you assert that curre nt is the flow of charge, and that charge is con servative—n either being created nor destroyed as it en ters a no de. Uni ess charge somehow builds up at a no de, which it does not, the n the rate at which charge en ters a node must equal the rate at which charge leaves the no de.There are several alter native ways to state Kirchhoff ' s curre nt law. The most com monly used stateme nt says that the sum of the curre nts flow ing into a node is zero as show n in Fig. 1-4a, in which case some of those curre nts must have n egative values while some have positive values. Equally valid would be the stateme nt that the sum of the curre nts leav ing a node must be zero as show n in Fig. 1-4b(aga in some of these curre nts n eed to have positive values and some n egative). Fin ally, we could say that the sum of the curre nts en teri ng a node equals the sum of the curre nts leav ing a node (Fig. 1-4c). These are all equivale nt as long as we un dersta nd what is meant about the directi on of curre nt flow whe n we in dicate it with an arrow on a circuit diagram. Curre nt that actually flows in the directi on show n by the arrow is give n a positive sig n. Curre nts that actuallyflow in the opposite direct ion have n egative values.(a) The sum of the curre nts into a node equals zero(b) The sum of the curre nts leav ing the node is zero(c) The sum of the curre nts en teri ng a node equals the sum of the curre nts leavi ng the node Note that you can draw curre nt arrows in any directio n that you want — that much is arbitrary — but once havi ng draw n the arrows, you must the n write Kirchhoff ' s curre nt law in a manner that is con siste nt with your arrows, as has bee n done in Fig.1-4. The algebraic soluti on to the circuit problem will automatically determ ine whether or not your arbitrarily determ ined direct ions for curre nts were correct.Example 1.1 Using Kirchhoff ' s Current LawA node of a circuit is shown with current direction arrows chosen arbitrarily. Havingpicked those directi on s, i1 = - 5 A, i2 = 3 A, and i3 = - 1 A. Write an expressi on for Kirchhoff ' s current law and solve for i4.Solution. By Kirchhoff ' s current law,i1 + i2 = i3 + i4 so thatThat is, i4is actually 1 A flowi ng into the no de. Note that i2, i3, and i4 are all en teri ng the no de, and i1 is the only curre nt that is leavi ng the no de.Part 3 Kirchhoff ' s Voltage LawElectr ons won ' t flow through a circuit uni ess they are give n some en ergy to help send them on their way. That “ push ” is measured in volts, where voltage is defi ned to be the amount nodenodenode1 + i4 i4 = - 1 AFig. 1-4 lllustrating various ways that Kirchhoff ' s current law can be statedof en ergy (w, joules) give n to a un it of charge,v=dw/dq A 12-V battery therefore gives 12 joules of en ergy to each coulomb of charge that it stores. Note that the charge does not actually have to move for voltage to have meaning. Voltage describes the potential for charge to do work.While curre nts are measured through a circuit comp onent, voltages are measured across componen ts. Thus, for example, it is correct to say that curre nt through a battery is 10 A, while the voltage across that battery is 12 V. Other ways to describe the voltage across a comp onent in clude whether the voltage rises across the comp onent or drops. Thus, for example, for the simple circuit in Fig. 1-1, there is a voltage rise across the battery and voltage drop across the light bulb. Voltages are always measured with respect to someth ing. That is, the voltage of the positive terminal of the battery is“ so many volts ” with respect to the negative terminal; or, the voltage at a point in a circuit is some amount with respect to some other poin t. In Fig. 1-5, curre nt through a resistor results in a voltage drop from point A to point B of VAB volts. V A and VB arethe voltages at each end of the resistor, measured with respect to some other point.The reference point for voltages in a circuit is usually desig nated with a ground symbol. While many circuits are actually groun ded — that is, there is a path for curre nt to flow directly into the earth —some are not (such as the battery, wires, switch, and bulb in a flashlight). When a ground symbol is show n on a circuit diagram, you should con sider it to be merely a reference point at which thevoltage is defi ned to be zero. Fig.1-6 points out how cha nging the node labeled as ground cha nges the voltages at each node in the circuit, but does not cha nge the voltage drop across each comp onent.(1-2)Fig. 1-5 The voltage drop from point A to point B is V AB, where VAB = VA - VBThe sec ond of Kirchhoff ' s fun dame ntal laws states that the sum of the voltages around any loop of a circuit at any instant is zero. This is known as Kirchhoff ' s voltage law (KVL). Just as was the case for Kirchhoff ' s curre nt law, there are alter native, but equivale nt, ways of stat ing KVL. We can, for example, say that the sum of the voltage rises in any loop equals the sum of the voltagedrops around the loop. Thus in Fig. 1-6, there is a voltage rise of 12 V across the battery and avoltage drop of 3 V across R1 and a drop of 9 V across R2. ------------- Notice that it doesn' t matterwhich node was labeled ground for this to be true. Just as was the case with Kirchhoff ' s current law, we must be careful about labeli ng and in terpret ing the sig ns of voltages in a circuit diagram in order to write the proper vers ion of KVL. A plus (+) sig n on a circuit comp onent in dicates a reference direct ion un der the assumpti on that the pote ntial at that end of the comp onent is higher than the voltage at the other end. Aga in, as long as we are con siste nt in writi ng Kirchhoff ' s voltage law, the algebraic soluti on for the circuit will automatically take care of sig ns.Part 5 Summary of Principal Electrical QuantitiesThe key electrical qua ntities already in troduced and the releva nt relati on ships betwee n these quantities are summarized in Table 1-1.Since electrical quantities vary over such a large range of magnitudes, you will often find yourself work ing with very small qua ntities or very large qua ntities. For example, the voltage created by your TV antenna may be measured in millionths of a volt (microvolts, 卩V), while the power gen erated by a large power stati on may be measured in billi ons of watts, or gigawatts (GW). To describe quantities that may take on such extreme values, it is useful to have a system of prefixes that accompany the units. The most commonly used prefixes in electrical engineering are give n in Table 1-2.Part 6 Ideal Voltage Source and Ideal Current SourceElectric circuits are made up of a relatively small nu mber of differe nt kinds of circuiteleme nts, or comp onen ts, which can be in terc onn ected in an extraord in arily large nu mber of ways.At this point in our discussion, we will concentrate on idealized characteristics of these circuit eleme nts, realiz ing that real comp onents resemble, but do not exactly duplicate, the characteristics that we describe here.An ideal voltage source is one that provides a give n, known voltage vs, no matter what sort ofload it is conn ected to. That is, regardless of the curre nt draw n from the ideal voltage source, it will always provide the same voltage. Note that an ideal voltage source does not have to deliver a con sta nt voltage; for example, it may produce a sinu soidally vary ing voltage —the key is that voltage is not a fun ctio n of the amount of curre nt draw n. A symbol for an ideal voltage source is show n in Fig. 1-7.A special case of an ideal voltage source is an ideal battery that provides a con sta nt dc output, as show n in Fig. 1-8. A real battery approximates the ideal source; but as curre nt in creases, the output drops somewhat. To acco unt for that drop, quite ofte n the model used for a real battery is an ideal voltage source in series with the internal resista nee of the battery.An ideal curre nt source produces a give n amount of curre nt is no matter what load it sees. As show n in Fig. 1-9, a commo nly used symbol for such a device is circle with an arrow in dicati ng the directi on of curre nt flow. While a battery is a good approximati on to an ideal voltage source, there is nothing quite so familiar that approximates an ideal curre nt source. Some tran sistor circuits come close to this ideal and are ofte n modeled with idealized curre nt sources.Section II The electric power systemChapter 1 Brief Introduction to The Electric Power SystemNew Words and ExpressionsMinimum a 最小prime mover n 原动机gen erator n 发电机load n 负载furn ace n 炉膛boiler n 锅炉fissi on able n 可裂变的fissi on able material 核燃料Part 1 Minimum Power systemelevatio n n 高度，海拔internal combusti on engine 内燃机 steam-drive n turbi ne 汽轮机hydraulic turbi ne 水轮机convert v 变换，转换 shaft n 传动轴，轴 torquen 力矩servomecha nism n 伺服机构* Elements of a minimum electric power system *Types of energy source *Types of prime mover *Types of electrical load*Functions of the control systemA minimum electric power system is shown in Fig.1-1, the system consists of an energy source, a prime mover, a generator, and a load.The en ergy source may be coal, gas, or oil burned in a furnace to heat water and gen erate steam in a boiler; it may be fissi on able material which, in a nu clear reactor, will heat water to produce steam; it may be water in a pond at an elevatio n above the gen erat ing stati on; or it may be oil or gas burned in an internal combusti on engine.The prime mover may be a steam-driven turbine, a hydraulic turbine or water wheel, or aninternal combustion engine. Each one of these prime movers has the ability to convert energy in the form of heat, falling water, or fuel into rotation of a shaft, which in turn will drive theEnergy source Prime nioverGenerator Lx>adContjolFig* 1-1 The tninfnmm electric power systemgen erator.The electrical load on the gen erator may be lights, motors, heaters, or other devices, alone or in comb in ati on. Probably the load will vary from mi nute to min ute as differe nt dema nds occur. The control system functions (are ) to keep the speed of the machines substantially constant and the voltage within prescribed limits, even though the load may cha nge. To meet these load con diti on s, it is n ecessary for fuel in put to cha nge, for the prime mover in put to vary, and for the torque on the shaft from the prime mover to cha nge in order that the gen erator may be kept at con sta nt speed. In additi on, the field curre nt to the gen erator must be adjusted to maintain con sta nt output voltage. The con trol system may in clude a man stati oned in the power pla nt who watches a set of meters on the gen erator output term in als and makes the n ecessary adjustme nts manu ally .In a moder n stati on, the con trol system is a servomecha nism that sen ses gen erator-output con diti ons and automatically makes the n ecessary cha nges in en ergy in put and field curre nt to hold the electrical output with in certa in specificati ons.Part 2 More Complicated Systems*Foreword*Cases of power system with out circuit breaker *Power system with circuit breakerNew Words and Expressions1. associated2. circuit3. circuit breaker4. dee nergize5. dee nergized6. outage n7. diagram8. switch out of9. switch offIn most situati ons the load is not directly conn ected to the gen erator term in als. More com monlya 联接的 n 电路n 断路器 vt 切断，断电 adj 不带电的停电 n 简图退出来，断开 v 切断，关闭the load is some distanee from the generator, requiring a power line connecting them. It is desirable to keep the electric power supply at the load with in specificati ons. However, the con trols are near the generator, which may be in another building, perhaps several miles away.If the dista nce from the gen erator to the load is con siderable, it may be desirable to in stall transformers at the generator and at the load end, and to transmit the power over a high-voltage line (Fig.1-2). For the same power, the higher-voltage line carries less current, has lower losses for the same wire size, and provides more stable voltage., TransformerTransformerPrime 〔Mover Generator f C High-voltage line—Fig- 1-2 A generator connected through transformers anda high-voltage line to a distant loadIn some cases an overhead line may be un acceptable. In stead it may be adva ntageous to use an un dergro und cable. With the power systems talked above, the power supply to the load must be in terrupted if, for any reas on, any comp onent of the system must be moved from service for maintenance or repair.Additi onal system load may require more power tha n the gen erator can supply. Ano ther gen erator with its associated tran sformers and high-voltage line might be added.It can be shown that there are some advantages in making ties between the generators (1) and at the end of the high-voltage lines (2 and 3), as shown in Fig.1-3. This system will operate satisfactorily as long as no trouble develops or no equipment needs to be taken out of service.Kig. 1-3 A system with para)lei operation or the generators t of the transformers andof the transmission lintsThe above system may be vastly improved by the in troducti on of circuit breakers, which may be ope ned and closed as n eeded. Circuit breakers added to the system, Fig.1-4, permit selected piece of equipme nt to switch out of service without disturb ing the rema in der of system. With this arran geme nt any eleme nt of the system may be dee nergized for maintenance or repair by operati on of circuit breakers. Of course, if any piece of equipme nt is take n out of service, the n the total load must be carried by the remaining equipment. Attention must be given to avoid overloads duri ng such circumsta nces. If possible, outages of equipme nt are scheduled at times when load requireme nts are below no rmal.Low-voltageo=^GeneratorsFig.1-5 shows a system in which three gen erators and three loads are tied together by threeFig* 1-4 A system with necessary circuit breakerstran smissi on lin es. No circuit breakers are show n in this diagram, although many would berequired in such a system.Fis- 1-S Three generators supplying threeloads over hlgh-voltnge trAnsmlsston linesChapter 2 Faults on Power SystemNew Words and Expressions1. fault2. in terfere neen 干扰，防碍6. feed (fed)给。

Semiconductor switches are very important and crucial components in power electronic systems.these switches are meant to be the substitutions of the mechanical switches,but they are severely limited by the properties of the semiconductor materials and process of manufacturing. 在电力电子系统，中半导体开关是非常重要和关键部件。

半导体开关将要替换机械开关,但半导体材料的性质和生产过程严重限制了他们。

Switching losses开关损耗Power losses in the power eletronic converters are comprised of the Switching losses and parasitic losses. 电力电子转换器的功率损耗分为开关损耗和寄生损耗the parasitic losses account for the losses due to the winding resistances of the inductors and transformers,the dielectric losses of capacitors,the eddy and the hysteresis losses. 寄生损失的绕组电感器、变压器的阻力、介电损耗的电容器,涡流和磁滞损耗the switching losses are significant and can be managed. 这个开关损耗是非常重要的,可以被处理。

they can be further divided into three components:(a)the on-state losses,(b)the off-state losses and the losses in the transition states. 他们可以分为三个部分: 通态损耗，断态损耗和转换过程中产生的损耗。

Semiconductor switches are very important and crucial components in powerelectronic systems.these switches are meant to be the substitutions of the mechanical switches,but they are severely limited by the properties of the semiconductor materials and process of manufacturing. 在电力电子系统，中半导体开关是非常重要和关键部件。

半导体开关将要替换机械开关,但半导体材料的性质和生产过程严重限制了他们。

Switching losses开关损耗Power losses in the power eletronic converters are comprised of the Switching losses and parasitic losses. 电力电子转换器的功率损耗分为开关损耗和寄生损耗the parasitic losses account for the losses due to the winding resistances of the inductors and transformers,the dielectric losses of capacitors,the eddy and the hysteresis losses. 寄生损失的绕组电感器、变压器的阻力、介电损耗的电容器,涡流和磁滞损耗the switching losses are significant and can be managed. 这个开关损耗是非常重要的,可以被处理。

they can be further divided into three components:(a)the on-state losses,(b)the off-state losses and the losses in the transition states. 他们可以分为三个部分: 通态损耗，断态损耗和转换过程中产生的损耗。

第一章第一篇sectiongTwo variables u(t) and i(t) are the most basic concepts in an electric circuit, they characterize the various relationships in an electric circuitu(t)和i(t)这两个变量是电路中最基本的两个变量，它们刻划了电路的各种关系。

Charge and CurrentThe concept of electric charge is the underlying principle for explaining all electrical phenomena. Also, the most basic quantity in an electric circuit is the electric charge. Charge is an electrical property of the atomic particles of which matter consists, measured in coulombs (C).电荷和电流电荷的概念是用来解释所有电气现象的基本概念。

也即，电路中最基本的量是电荷。

电荷是构成物质的原子微粒的电气属性，它是以库仑为单位来度量的。

We know from elementary physics that all matter is made of fundamental building blocks known as atoms and that each atom consists of electrons, protons, and neutrons. We also know that the charge e on an electron is negative and equal in magnitude to 1.60210×10 19C, while a proton carries a positive charge of the same magnitude as the electron. The presence of equal numbers of protons and electrons leaves an atom neutrally charged.我们从基础物理得知一切物质是由被称为原子的基本构造部分组成的，并且每个原子是由电子，质子和中子组成的。

电力系统现代社会比以往任何时候更为依赖电能供应。

如果全世界电能供应全部中断的话，不可想象整个世界将会糟糕到什么程度。

为现代社会供电的电力系统(或电能系统)已经成为这个工业化世界不可缺少的组成部分。

托马斯.爱迪生建立了世界上第一个完整的电力系统(包括一台发电机、电能、电缆、熔断器测量仪表和负载)，它就是位于纽约市的具有历史意义的珍珠街发电厂，该电厂位于1882年9月投入运行。

这是一个直流系统，由一台蒸汽机驱动的电流发电机和方圆大约1.5km范围内的59个用户组成。

负荷完全由白炽灯组成，通过地下电缆系统用110v电压供电，随后几年内，类似的电力系统在世界各地的城市陆续投运。

由于法兰克.史博格在1884年研制出电动机，电动机负荷开始接入这类系统。

由此开始电力系统逐渐发展为世界上最大的工业系统之一。

尽管初期直流系统广泛采用，但后来它们几乎完全被交流系统取代。

到1886年，直流系统的缺点变得日益明显。

直流系统只能在发电机的短距离范围内输送电力。

对于长距离输送电而言，为了将输电损耗(I2R)和电压降落控制在可接受的水平，必须采用高的电压等级。

如此高的电压对于发电还是用电都是不可接受的的，因此必须有一个方便的电压变换方法随着法国巴黎的吕西安.戈拉尔和约翰.吉布斯发明了变压器和交流输电方式，交流电力系统得到了广泛的应用。

1889年，第一条交流输电线路在北美洲投入运行，它位于奥勒冈州的威廉特瀑布和波特兰之间。

这是一条单相输电线路，输电电压4000v，输电距离21km。

在尼古拉.特斯拉发明多相输电系统后，交流输电系统变得更具优势。

到1888年，拥有了交流电动机、发电机、变压器和输电系统等多项技术专利。

威斯汀豪斯公司购买了这些早期发明的专利，这些专利为当今的交流电力系统奠定了基础。

19世纪80年代，在将电力工业的标准模式定为直流或交流的问题上产生了激烈的争论。

到了世纪之交，交流系统战胜了直流系统，这是因为下列原因：1在交流系统中可以方便地实现电压等级的交换，从而实现了在不同电压的水平上发电、输电用电的灵活性。