机电专业英语讲义

机电专业英语32学时宋春华Email:[e-mail]2011年1月2007级机电专业本科讲义机电专业英语教材：王军教授、宋舒教授主编的由重庆大学出版社出版的《自动化专业英语》基本目标：基本能够比较顺利、准确地阅读机电专业方面的英文书刊、文献、技术资料，在这方面具备一定的翻译和沟通、表达、交流能力。SpecializedEnglishforElectromechanization(Electro-Mechanism)Howtospeak“专业英语”inEnglish？Andhowabout“机电专业英语”?ContentElectronicTechnology•BipolarJunctionTransistors•UJTThyristorsandSCRs•OperationalAmplifiers•Flip-Flops•DigitalSystemDecoding•FiltercircuitContentElectronicTechnology•Direct-currentRegulation•PhaseControl•UnijuncityTransistorPulseTriggeringControlTheory•IntroductiontoControlSystemContentControlTheory•PerformanceSpecificationsofControlSystem•Second-OrderSystems•DigitalControlSystem•StateEquationContentComputerTechnology•TheApplicationofComputerElectricDrive•DCMotorsBipolarJunctionTransistorWordsandTermsTransistor[træn´zistə]:[电子]晶体管Bipolar[bai´pəulə]:有两极的,双极的Polarity[pəu´læriti]:极性Negative[´negətiv]:负的,阴性的semiconductor[´semikən´dΛktə]:半导体crystal[´kristl]:结晶，晶体，晶粒BipolarJunctionTransistorWordsandTermssymbol[´simbəl]:符号,记号,象征emitter[i´mitə]:发射极collector[kə´lectə]:集电极formula[´fƆ:mjulə]:公式,规则,客套语reverse[ri´və:s]:相反的,倒转的,颠倒的biased[`baiəst]:结果偏倚的,[数]有偏的BipolarJunctionTransistorTextToday,industrialelectronicsystemsemployseveraldevicesthataredescribedbythetermtransistor.目前，工业电子系统使用了多种由术语晶体管描述的器件。BipolarJunctionTransistorTextEachtypeoftransistorhasdifferentcharacteristicsandoperationalconditionsthatareusedtodistinguishitfromothers.每种晶体管都有区别于其它种类的特征和工作环境。BipolarJunctionTransistorTextInthefirstpartofthisdiscussion,weareconcernedwiththebipolarjunctiontransistor.Structurally,thistransistorisdescribedasbipolarbecauseithastwodifferentcurrent-carrierpolarities.首先探讨双极型晶体管。从结构上看，这种晶体管被称为双极是因为它具有两种不同的电流载流子电极。BipolarJunctionTransistorTextHolesarepositivecurrentcarriers,whereaselectronsarenegativecurrentcarriers.空穴是正的载流子，电子是负的电流载流子。BipolarJunctionTransistorTextTwodistinctkindsofsemiconductorcrystalsareconnectedtogetherbyacommonelement.两种截然不同的半导体晶体通过公共元件连接在一起。BipolarJunctionTransistorTextThestructureofthisdeviceissimilartothatoftwodiodesconnectedbacktoback,withonecrystalbeingcommontobothjunctions.Thecentermaterialisusuallymadethinnerthanthetwooutsidepieces.该器件的结构类似于背靠背连接的两个二极管的结构，一个晶体同时属于两个结。其中间的材料通常比两个外边的作得窄些。BipolarJunctionTransistorTextIntheoperationofasinglePNdiodejunction,forwardbiasingcausesconductionandreversebiasingcausesnonconduction.单个PN二结的工作情况是：正向偏置促使其导通，反向偏置导致其截止。BipolarJunctionTransistorTextInatransistor,thisruledoesnotapplydirectlybecausetwojunctionsareinvolved.因为晶体管包含两个结，该规则不能直接应用Forexample,whentheemitter-basejunctionisforwardbiased,itcausesalargeamountofIEtoenterthebaseregion.例如，其发射-基极处于正向偏置时，它会促使大量的IE进入基区。BipolarJunctionTransistorTextReversebiasingofthebase-collectorjunctionwouldordinarilyrestrictthiscurrent.而基-集电极的反向偏置会限制该电流。Butduetothethinbasestructure,IEwillimmediatelyenterintothecollectorcurrentICoroutputcurrent.但因基区窄，IE会很快进入集极电流IC或输出电流.BipolarJunctionTransistorTextForwardbiasingoftheemitter-basejunctionthereforealtersorreducesthereversebiasingeffectofthebase-collectorjunctioninnormaltransistoroperation.因而，在一般的晶体管工作中，发射-基结的正向偏置会改变或减少基-集结反向偏置的影响。BipolarJunctionTransistorTextAtransistorisprimarilyclassifiedasacurrent-operatingdevice.ThismeansthattheoutputorcollectorICwilloccuronlywhentheemitter-baseisforwardbiasedandproducingbasecurrent.晶体管被划分为基本电流型器件。这意味着仅仅当发射-基结处于正偏且有基极电流IB时才会有其输出或集电极电流ICBipolarJunctionTransistorTextWhenthebasecurrentceases,collectorcurrentstopsandthetransistorbecomenonconductive.Thisconditioniscalledcutoff.当基极电流消失时，集电极电流停止，晶体管处于非导通状态。这种情况就称为截止。BipolarJunctionTransistorTextOntheotherhand,ifanexcessiveamountofbasecurrentoccurs,thetransistorisdrivenintosaturation.Whenthisconditionoccurs,afurtherincreaseinIBwillnotcauseacorrespondingchangeinIC.相反，如果基极电流过大，晶体管处于饱和状态。在这种情况下，再增加IB不会引起IC的相应变化。BipolarJunctionTransistorTextWhenamplitudecontrolisbeingachieved,atransistorisrarelyoperatesinthesaturationregion.Whenatransistorisusedasaswitch,itusuallyoperatesinthesaturationregion.进行幅值控制时晶体管几乎不会处于饱和区。而当它作为开关使用时，经常工作在饱和区。UJTThyristorsandSCRsWordsandTermsunijunction[´ju:ni´dӡΛηkʃən]:单结emitter[i´mitə]:发射极collector[kə´lectə]:集电极formula[´fƆ:mjulə]:公式,规则,客套语reverse[ri´və:s]:相反的,倒转的,颠倒的biased[`baiəst]:结果偏倚的,[数]有偏的UJTThyristorsandSCRsTextThyristorsshouldnotbeconfusedwithbipolarjunctiontransistorsorfield-effecttransistors.不应将晶闸管与双结型晶体管（bipolarjunctiontransistors，BJTs）或场效应管（field-effecttransistors，FETs）混淆起来.UJTThyristorsandSCRsTextBJTsandFETsarebothcapableofperformingswitchingoperations.Asarule,thesedevicesarenotasefficientasthyristoranddonothavethepower-handlingcapability.BJTs与FETs都能够完成开关操作。按照惯例，这些器件并没有晶闸管那么有效率且不具备功率（电力）处理能力。UJTThyristorsandSCRsTextThyristorsareusedaspowercontroldevices,whereastransistorsareprimarilyusedinamplifyingapplications.晶闸管通常用作电力控制器件，而晶体管主要用于信号放大。UJTThyristorsandSCRsTextAvarietyofunidirectionalthyristorsisnowbeingusedinindustrialelectronicapplications.Oneofthefirsttobedevelopedwasthesilicon-controlledrectifier(SCR).Thetermthyristorwasderivedformthewordsthyratron-transistor.工业电子应用系统目前使用了很多种单向晶闸管。可控硅整流器（silicon-controlledrectifi