电路基础-英文教学-1.ppt

电路基础-英文教学-1.ppt

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Chapter1Basicconcepts,要求深刻理解与熟练掌握的重点内容有：

1.理想元件与电路模型概念,线性与非线性的概念。

2.电压、电流及其参考方向的概念。

3.电阻元件、电感元件、电容元件,电压源、电流源和受控源的伏安关系及功率的计算。

4.基尔霍夫电流定律和基尔霍夫电压定律。

要求一般理解与掌握的内容有：

5.时变与非时变的概念。

难点：

参考方向，受控源，功率计算。

1-1Introduction,1-2BasicConceptsandSystemofUnits,1-3ChargeandCurrent,1.4Voltage,1.5PowerandEnergy,1-6CircuitElements,1-9SummaryandReview,1-1Introduction,instrumentation,仪表,topology,拓扑,Theschematicdiagram,theInternationalSystemofUnits（SI）,国际单位制,theGeneralConferenceonWeightsandMeasures,国际计量大会,原理图,1.Terms,electron,电子,proton,质子,neutron,anexternalelectromotiveforce（emf）,外电动势,potentialdifference,电位差,instantaneouspower,瞬时功率,中子,First,areal-worldproblemisidentified;second,theproblemismodeled;third,themodelisanalyzed;andfourth,theresultsareappliedtotheoriginalphysicalproblem.,2.Whystartwithcircuittheory?

Thesolutionofanengineeringproblemnormallyproceeds:

1-2BasicConceptsandSystemofUnits,1.2.1SystemofUnits,1.2.2BasicConcepts,Anelectriccircuitisaninterconnectionofelectricalelements.,Activeelements:

capableofgeneratingenergy,suchasgenerators,batteriesetc.,Passiveelements:

resistors,capacitorsandinductors,Idealcircuitelements:

理想电路元件Lumpedparameterelements集中参数元件Idealindependentsource理想电源元件Idealload理想负载元件Idealcouplingelements理想耦合元件Lumpedparameterelements&distributedelements集中参数与分布参数,Chargeisanelectricalpropertyatomicparticlesofwhichmatterconsists,measuredincoulombs（C）,Anelectrone=-1.6021019CIn1Cofcharge,thereare1/（1.60210-19）=6.241018electrons3.Thelawofconservationofcharge,Note,1-3ChargeandCurrent1.3.1Charge电荷,Electriccurrentisthetimerateofchangeofcharge,measuredinamperes（A）.,1A=1C/1s（秒）1kA=1000A，1mA=10-3A，1A=10-6A，1nA=109A,1.3.2Current电流：

Analternativecurrent（ac）isacurrentthatvariessinusoidallywithtime.时变电流,Andre-MarieAmpere（1775-1836）安培,Adirectcurrent（dc）isacurrentthatremainsconstantwithtime.直流电流,Tospecifythecurrentinaconductor,weneedbothareferencedirectionandnumericalvalue,whichcanbepositiveornegative.,I0实际方向与参考方向相同I0实际方向与参考方向相反,1.3.3Currentreferencedirections电流的参考方向,Voltage（orpotentialdifference）istheenergyrequiredtomoveaunitchargethroughanelement,measuredinvolts（V）.Uab=W/qV，kV，mV，V,AlessandroAntonioVolta（1745-1827）伏特,1.4Voltage1.4.1VoltageofPotential电位,Potentialreferencepolarity电位的参考极性（零电位点）参考点：

LetUb=0,Ua=U,Uab=U=Ua-Ub，pointaisatapotentialofUabvoltshigherthanpointb.,1.4.2Voltage电压,Voltagereferencedirections,Keepinmindthatelectriccurrentisalwaysthroughanelementandthatelectricvoltageisalwaysacrosstheelementorbetweentwopoints.,CheckYourUnderstandingWhatthedifferencebetweenUabandU?

Uab=U=US+RIUab=-Uba=UU=USRI,Poweristhetimerateofexpendingorabsorbingenergy,measuredinwatts（W）.,Instantaneouspower,1.5PowerandEnergy,Indccircuit:

P=IU,Powerunit:

W，kW，1MW106W,Whenthecurrententersthroughthepositiveterminalofanelement,p=+ui.Ifthecurrententersthroughthenegativeterminal,p=-ui.,p0PowerabsorbP0Powersupply,Accordingtolawofconservationofenergy,wehave,Inasourceset,thecurrentreferencedirectionisdirectedoutofthe+polaritymarking（orthefirstsubscript）ofthevoltage.Inaloadset,thecurrentreferencedirectionisdirectedintothe+polaritymarking（orthefirstsubscript）ofthevoltagereferencedirection.,fromEQ（1-1）,theenergyabsorbingorsuppliedbyanelementfromtimet0totis,Unitisjoules（J）,1Wh=3600J,Example：

TheelectronbeaminaTVpicturetubecarries1015electronspersecond.Asadesignengineer,determinethevoltageU0neededtoacceleratetheelectronbeamtoachieve4W.Solution：

1-6CircuitElements,（Chapter6）,Passiveelements（无源元件）,Activeelements（有源元件）,Resistors电阻,Inductors电感,Capacitors电容,Independentsource独立电源,dependentsource受控源,Voltagesource电压源,currentsource电流源,CCCSCCVSVCVSVCCS,Summary:

1.Current,2.Voltage,3.Potential,4.Power,2.P0absorborexpendpower（吸收功率）P0supplypower（发出功率）,Emphasis重点,1.currentandvoltagereferencedirection,Anidealindependentsourceisanactiveelementthatprovidesaspecifiedvoltageorcurrentthatiscompletelyindependentofothercircuitvariable.,1.6.1IdealIndependentSources,1、理想电压源IdealVoltageSource,Theidealvoltagesourcemaintainsitsprescribedvoltage,independentofitsoutputcurrent.Generalsymbolforavoltagesource,graphicalcharacteristicofadcvoltagesource:

thecurrentisdeterminedbytheload（负载）U=0，Shortcircuit,maintainsitsvoltage,Theidealcurrentsourceproducesitsprescribedcurrent,independentofitsoutputvoltage.Generalsymbolofacurrentsource,2、独立电流源IdealCurrentSource,graphicalcharacteristicofadccurrentsource,maintainsitscurrent,thevoltageisdeterminedbytheload（负载）,Anidealdependent（orcontrolled）sourceisanactiveelementinwhichthesourcequantityiscontrolledbyanothervoltageorcurrent.,1.6.2、受控电源CONTROLLEDSOURCES,CCCS：

Acurrent-controlledcurrentsource：

currentgain,dimensionless,VCCS：

Avoltage-controlledcurrentsourceg：

transconductance（S）,VCVS：

Avoltage-controlledvoltagesource：

voltagegain,dimensionless,CCVS：

Acurrent-controlledvoltagesource：

r:

transresistance（）,Example：

R1=1，R2=2，R3=3，=3，US3=3V.Findopen-circuitvoltageU22（开路电压）,Solution：

22开路：

Io=0，Io=0，,1.6.3电阻、电感、电容元件Resistors,InductorsandCapacitors,一、电阻元件Resistors,R=，开路/断路Opencircuit:

acircuitelementwithresistanceapproachinginfinity.RR=0，短路Shortcircuit:

acircuitelementwithresistanceapproachingzero.R0,Ohmslawstatesthatthevoltageacrossaresistorisdirectlyproportionaltothecurrentflowingthroughtheresistor.,u（t）=Ri（t）U=RI，I=GU,GeorgSimonOhm（1787-1845），欧姆,P=UI=RI2=U2/R=GU2,CheckYourUnderstandingUab=?

Uad=?

Uac=?

Ucd=?

Ua-R1I1+E1=Ub；Uab=R1I1-E1；Uad=R1I1-E1-R3I3-E3；Uac=R1I1-E1+E2-R2I2；Ucd=R2I2-E2-R3I3-E3；,二、电感器Inductors,（t）=Li（t）-（Wb）（韦伯）L-（H）亨利I-（A）（安培）,graphicalcharacteristic（Wb-A）,Thevoltage-currentcharacteristicsofaninductor,Theenergystoredintheinductor:

三、电容器Capacitors,Circuit-theorydefinitionofacapacitor:

q（t）=Cu（t）,C-法拉（F），1F=10-6F，1pF=10-12Fq-库仑（C）V-伏特（V）,MichaelFaraday（1791-1867），法拉弟,线性电容,（C-V曲线）,Theenergystoredinthecapacitor:

Thevoltage-currentcharacteristicsofancapacitor:

小结,IdealCurrentSource（IS,iS）

（1）Current不随Load变化而变化。

（2）Voltage随Load变化而变化。

2.IdealVoltageSource（IS,iS）

（1）Voltage不随Load变化而变化。

（2）Current随Load变化而变化。

3.Controlledsourses受控电源,4.ResistorOhmslaw,5.Inductor,6.Capacitor,1.9Summary,Anelectriccircuitconsistsofelectricalelementsconnectedtogether.TheInternationalSystemofUnits（SI）istheinternationalmeasurementlanguage,whichenablesengineerstocommunicatetheirresults.Fromthesixprincipalunits,theunitsofotherphysicalquantitiescanbederived.Currentistherateofchargeflow.Voltageistheenergyrequiredtomove1Cofchargethroughanelement.,5.Poweristheenergysuppliedorabsorbedperunittime.Itisalsotheproductofvoltageandcurrent.,6.Accordingtothepassivesignconvention,powerassumesapositivesignwhenthecurrententersthepositivepolarityofthevoltageacrossanelement.,7.Anidealvoltagesourceproducesaspecificpotentialdifferenceacrossitsterminalsregardlessofwhatisconnectedtoit.Anidealcurrentsourceproducesaspecificcurrentthroughitsterminalsregardlessofwhatisconnectedtoit.,8.Voltageandcurrentsourcescanbedependentorindependent.Adependentsourceisonewhosevaluedependsonsomeothercircuitvariable.,9.TwoareasofapplicationoftheconceptscoveredinthischapteraretheTVpicturetubeandelectricitybillingprocedure.,