电路基础 英文教学 1

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•1-3 ChargeandCurrent•1.4 Voltage•1.5PowerandEnergy

•1-6CircuitElements

•1-9SummaryandReview

1-1Introductioninstrumentation仪表

topology拓扑TheschematicdiagramtheInternationalSystemofUnits(SI)国际单位制theGeneralConferenceonWeightsandMeasures国际计量大会原理图1.Termselectron电子proton质子neutronanexternalelectromotiveforce(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:ThesixbasicSIunitsQuantitybasicunitSymbolLengthmetermMasskilogramkgTimesecondsElectriccurrentampereAThermodynamictemperaturekelvin

KLuminousintensitycandelacd

热力学的光强度绝对温标1-2BasicConceptsandSystemofUnits1.2.1SystemofUnits1.2.2BasicConcepts

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=-1.602×10－19CIn1Cofcharge,thereare1/(1.602×10-19)=6.24×1018electrons3.ThelawofconservationofchargeNote1-3 ChargeandCurrent

1.3.1 Charge电荷Electriccurrentisthetimerateofchangeofcharge,measuredinamperes(A).1A=1C/1s(秒)1kA=1000A，1mA=10-3A，1A=10-6A，1nA=10－9A1.3.2Current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.aI/ibRbRaI/iI>0实际方向与参考方向相同I<0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，VAlessandroAntonioVolta(1745-1827)伏特1.4 Voltage

1.4.1VoltageofPotential电位Potentialreferencepolarity电位的参考极性(零电位点）参考点：LetUb=0,Ua=UUab=U=Ua-Ub，pointaisatapotentialofUabvoltshigherthanpointb.1.4.2Voltage电压VoltagereferencedirectionsKeepinmindthatelectriccurrentisalwaysthroughanelementandthatelectricvoltageisalwaysacrosstheelementorbetweentwopoints.aIbRU=5vaIbRU=-5vCheckYourUnderstandingWhatthedifferencebetweenUabandU?

Uab=U=US+RIUab

=-Uba=UU=－US－RIPoweristhetimerateofexpendingorabsorbingenergy,measuredinwatts(W).吸收消耗Instantaneouspower1.5PowerandEnergy

Indccircuit:P=IUPowerunit:W，kW，1MW＝106WWhenthecurrententersthroughthepositiveterminalofanelement,p=+ui.Ifthecurrententersthroughthenegativeterminal,p=-ui.aIbUaIbUp>0PowerabsorbP<0Powersupply

Accordingto

lawofconservationofenergy,wehave(a)：P=UI(b)：P=UI，(c):P=-UI，Inasourceset,thecurrentreferencedirectionisdirectedoutofthe+polaritymarking(orthefirstsubscript)ofthevoltage.Inaloadset,thecurrentreferencedirectionisdirectedintothe+polaritymarking(orthefirstsubscript)ofthevoltagereferencedirection.下标fromEQ(1-1),theenergyabsorbingorsuppliedbyanelementfromtimet0

totisUnitisjoules(J)1Wh=3600JExample：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CCCSCCVSVCVSVCCSSummary:1.Current2.Voltage3.Potential4.PoweraIbUaIbU2.P>0absorborexpendpower(吸收功率）

P<0supplypower(发出功率）•Emphasis重点1.currentandvoltagereferencedirection

aIbRUaIbRUU=IRU=-IR（1）参考方向的假设是解题的第一步。（2）参考方向的假设可以是任意的，但是一但假设了，在整个解题的过程中不能更改。（3）关联的参考方向非关联的参考方向Anidealindependentsourceisanactiveelementthatprovidesaspecifiedvoltageorcurrentthatiscompletelyindependentofothercircuitvariable.1.6.1IdealIndependentSources

1、理想电压源IdealVoltageSourceTheidealvoltagesourcemaintainsitsprescribedvoltage,independentofitsoutputcurrent.Generalsymbolforavoltagesource规定的符号graphicalcharacteristicofadcvoltagesource:thecurrentisdeterminedbytheload（负载）U=0，Shortcircuitmaintainsitsvoltage绘画的特性的Theidealcurrentsourceproducesitsprescribedcurrent,independentofitsoutputvoltage.Generalsymbolofacurrentsource2、独立电流源IdealCurrentSource

graphicalcharacteristicofadccurrentsource规定的符号特性曲线maintainsitscurrent

thevoltageisdeterminedbytheload（负载）Anidealdependent(orcontrolled)sourceisanactiveelementinwhichthesourcequantityiscontrolledbyanothervoltageorcurrent.1.6.2、受控电源CONTROLLEDSOURCESI1aI1CCCSgU1VCCS+U1_CCCS：Acurrent-controlledcurrentsource：currentgain,dimensionlessVCCS：Avoltage-controlledcurrentsourceg：transconductance（S）

电导无纲量mU1VCVS+U1_I1rI1CCVSVCVS：Avoltage-controlledvoltagesource：voltagegain,dimensionlessCCVS：Acurrent-controlledvoltagesource：r:transresistance（）无纲量

电阻Example：R1=1，R2=2，R3=3，=3，US3=3V.Findopen-circuitvoltage

U22’（开路电压）Solution：22’开路：Io=0，Io=0，CheckYourUnderstanding:findtheopen-circuitvoltageUab∴1.6.3电阻、电感、电容元件

Resistors,InductorsandCapacitors一、电阻元件Resistorsgraphicalcharacteristic（V-A)线性非时变电阻线性时变电阻非线性非时变电阻非线性时变电阻R=∞，开路/断路Opencircuit:acircuitelementwithresistanceapproachinginfinity.R≈∞R=0，短路Shortcircuit:acircuitelementwithresistanceapproachingzero.R≈0Ohm’slawstatesthatthevoltageacrossaresistorisdirectlyproportionaltothecurrentflowingthroughtheresistor.u(t)=Ri(t)U=RI，I=GUGeorgSimonOhm(1787-1845)，欧姆绝对正比于G=1/Rmhosorsiemens(S)（）P=UI=RI2=U2/R=GU2CheckYourUnderstandingUab=?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）iL(t)L+_uL(t)graphicalcharacteristic（Wb-A)

iy(Wb)线性电感

i

非线性电感y(Wb)Thevoltage-currentcharacteristicsofaninductoriL(t)L+_uL(t)iL(t)L+_uL(t)Theenergystoredintheinductor:三、电容器CapacitorsCircuit-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

u

非线性电容q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CCCS：Acurrent-controlledcurrentsourceVCCS：Avoltage-controlledcurrentsourceVCVS：Avoltage-controlledvoltagesourceCCVS：Acurrent-controlledvoltagesource,：dimensionless

r:（）g：（S）4.ResistorOhm’slaw5.Inductor6.Capacitor1.9SummaryAnelectriccircuitconsistsofelectricalelementsconnectedtogether.TheInternationalSystemofUnits(SI)istheinternationalmeasurementlanguage,whichenablesenginee