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1、Part2ElectricalMachine,ControlComponentandSensorP80〜95IntroductiontoElectricalMachines5.1BRIEFHISTORYOFELETRICALMACHINESElectricalmachineryhasbeeninexistenceformanyyears・Theapplicationsofelectricalmachineshaveexpandedrapidlysincetheirfirstusemanyyearsago.Atthepresenttime,applicationscontinu

2、etoincreaseatarapidrate.ThomasEdisonisgivencreditfordevelopingtheconceptofwidespreadgenerationanddistributionofelectricalpower.Heperformeddevelopmentalworkondirect-current(DC)generatorswhichweredrivenbysteamengines・Edison'sworkwithelectricallightsandpowerproductionledthewaytothedevelopmento

3、fDCmotorsandassociatedcontrolequipment.Mostearlydiscoveriesrelatedtoelectricalmachineryoperationdealtwithdirect-currentsystems.Alternating-current(AC)powergenerationanddistributionbecamewidespreadashorttimelater.TheprimaryreasonforconvertingtoACpowerproductionanddistributionwasthattransform

4、erscouldbeusedtoincreaseACvoltagelevelsforlong・distancedistributionofelectricalpower.Thusthediscoveryoftransformers（变压器）allowedtheconversionofpowerproductionanddistributionsystemsforDCtoACsystems.Presently,almostallelectricalpowersystemsproduceanddistributethree-phasealternatingcurrent.Tran

5、sformersallowthevoltageproducedbyanACgeneratortobeincreasedwhiledecreasingthecurrentlevelbyacorrespondingamount.Thisallowslong-distancedistributionatareducedcurrentlevel,reducespowerlosses,andincreasessystemefficiency.Theuseofelectricalmotors（电机）hasincreasedforhomeappliancesfordrivingmachin

6、esandandautomatedindustrialThusmotordesignandmotorswhichwereusedandindustrialandcommercialapplicationssophisticatedequipment.Manymachinesequipmentnowrequireprecisecontrol.complexityhaschangedsinceearlyDCprimarilywithrailroadtrains.Motorcontrolmethodshavenowbecomemorecriticaltotheefficientan

7、deffectiveoperationofmachinesandequipment.Suchinnovations（新事物）asservo（伺Jj艮）controlsystemsandindustrialrobotshaveledtonewdevelopmentsinmotordesign.Ourcomplexsystemoftransportationhasalsohadanimpact（7中击）ontheuseofelectricalmachines・Automobilesandothermeans