(完整版)电工学原理及应用(Electrical-Engineering)经典双语详解讲义-(1)

ElectricalEngineeringPrinciplesandA[e-mail]ndElectronicsIIHeiscurrentlyalecturerwiththeCollegeofInformationEngineering,ZhejiangUniversityofTechnology.Hisresearchinterestsincludesupportvectormachine,neuralnetworkcontrol,adaptivecontrolwithapplicationstomotioncontrolsystems,etc.QiangChenwasborninShandongprovince,in1984.HereceivedtheB.S.degreeinmeasurementandcontroltechnologyandinstrumentfromHebeiAgriculturalUniversityin2002andthePh.DdegreeincontrolscienceandengineeringfromBeijingInstituteofTechnologyin2012.FinalScore=20%experimentperformance+30%exerciseperformance+50%examscoreElectricalEngineeringandElectronicsIIChapter1IntroductionElectricalEngineeringandElectronicsII4CourseHours1.Introduction1.1OverviewofElectricalEngineering1.2Circuits,Currents,andVoltages1.3PowerandEnergy1.4Kirchhoff'sCurrentLaw1.5Kirchhoff'sVoltageLaw1.6IntroductiontoCircuitElements1.7IntroductiontoCircuits1.1OverviewofElectricalEngineeringElectricalsystemshavetwomainobjectives:•Togather(采集),store(存储),process(处理),transport(转换),andpresent(显示）information•Todistributeandconvertenergybetweenvariousforms•Communicationsystemsradio,satelliteTV,cellphone.•Computersystemsprocessandstoreinformationindigitalform.•Controlsystemsgatherinformationwithsensorsanduseelectricalenergytocontrolaphysicalprocess.•Electromagneticsisthestudyandapplicationofelectricandmagneticfields.•Electronicsisthestudyandapplicationofmaterials,devicesandcircuitsusedinamplifyingandswitchingelectricalsignals.•Photonicsisanexcitingnewfieldofscienceandengineeringthatpromisestoreplaceconventionalcomputing.•Powersystemsconvertenergytoandfromelectricalform.•Signalprocessingisconcernedwithinformation-bearingelectricalsignals.•ElectricalEngineeringSubdivisionsReasons:•TopasstheFundamentalsofEngineering(FE)Examination•Tohaveabroadknowledgeandyoucanleaddesignprojectsinyourownfield•Tobeabletooperateandmaintainelectricalsystems•Tocommunicatewithelectricalengineeringconsultants•WhyStudyElectricalEngineering?1.2Circuits,CurrentsandVoltagesSimpleexample:theheadlightcircuitofanautomobile•ElectricalCircuitAnelectricalcircuitconsistsofvarioustypesofcircuitelementsconnectedinclosedpathsbyconductors.iuuLLuRuCRCR0EURabcd++--IVCCRBRCIC+_UCE+_VCC+_UBEIBBI•国标符号•Electricalcurrentisthetimerateofflowofelectricalchargethroughaconductororcircuitelement.•Theunitsareamperes(A),whichareequivalenttocoulombspersecond(C/s).•ElectricalCurrentThechargeonanelectronis-1.602E-19Ctttqdttitqdttdqti0)()()()()(0•ElectricalCurrent•Actualdirection：MovingdirectionofpositivechargeFig.1.4CurrentisthetimerateofchargeflowthroughacrosssectionofconductororcircuitelementTheelectricalcurrentflowingthroughtheelementinthereferencedirectionisgivenby022)(00)(100tetqttqt020000)()(:100tetdttdqtiSolutiont2))((Ctq0tExample1.1DeterminingCurrentGivenCharge0)(mst4002000200)(100tetitSupposethatchargeversustimeisgivenbyDirectCurrentWhenacurrent’sdirectionisconstantwithtime,wesaythatwehavedirectcurrent,abbreviatedasDC.AlternatingCurrentOntheotherhand,acurrentthatvarieswithtime,reversingdirectionperiodically,iscalledalternatingcurrent,abbreviatedasAC..Sinusoidalcurrent三角波方波•ReferenceDirectionsi1=-2AActualDirectioni2=2Ai3=-1A•Double-SubscriptNotationforCurrents1abiAExample:if,then1baiA•VoltagesThevoltageassociatedwithacircuitelementistheenergytransferredperunitofchargethatflowsthroughtheelement.Theunitsofvoltagearevolts(V),whichareequivalenttojoulespercoulomb(J/C).Forexample,considerthestoragebatteryinanautomobile.Thevoltageacrossitsterminalsis12V.Thismeansthat12Jaretransferredtoorfromthebatteryforeachcoulombthatflowsthroughit.•VoltagesVoltagesareassignedpolaritiesthatindicatethedirectionofenergyflow.Ifpositivechargemovesfromthepositivepolaritythroughtheelementtowardthenegativepolarity,theelementabsorbsenergythatappearsasheat,mechanicalenergy,storedchemicalenergy,orassomeotherform.Ontheotherhand,ifpositivechargemovesfromthenegativepolaritytowardthepositivepolarity,theelementsuppliesenergy.•Voltagespositivechargepositivechargepositivepolaritynegativepolarity•Voltages’referencepolarityVba=-VabVab=-5VAnothertwowaystoindicatethereferencepolarityofavoltage:doublesubscriptsonthevoltagevariableandanarrow+-1.3PowerAndEnergyConsiderthecircuitelementshowninFigure1.14.Becausethecurrentiistherateofflowofchargeandthevoltagevisameasureoftheenergytransferredperunitofcharge,theproductofthecurrentandthevoltageistherateofenergytransfer.Inotherwords,theproductofcurrentandvoltageispower.21)()()()(ttdttpwtitvtpUnit:WattUnit:JoulePowerAndEnergyReviewDefinitions:1.Currenti—therateofchargeflow;2.Voltagev—ameasureoftheenergytransferredperunitofcharge;3.Power—therateofenergytransfer(theproductofthecurrentandthevoltage).4.ReferencedirectionandActualdirectionWheniorvhasapositivevalue,thetwodirectionsaresame;Wheniorvhasanegativevalue,thetwodirectionsareopposite.IUab＋－Asshowninthefigureabove,thecurrentreferenceentersthepositivepolarityofthevoltage,wecallthisar