DC

Compositionstructure

ThestructureofaDCmotorshouldbecomposedoftwoparts:thestatorandtherotor.ThestaticpartoftheDCmotoriscalledthestator.Themainfunctionofthestatoristogenerateamagneticfield,whichiscomposedoftheframe,themainmagneticpole,thecommutatingpole,theendcover,thebearingandthebrushdevice.Thepartthatrotatesduringoperationiscalledtherotor.Itsmainfunctionistogenerateelectromagnetictorqueandinducedelectromotiveforce.ItisthehuboftheDCmotorforenergyconversion,soitisusuallycalledthearmature.Composedofafanandafan.

Stator

(1)Mainmagneticpole

Thefunctionofthemainmagneticpoleistogenerateanairgapmagneticfield.Themainmagneticpoleiscomposedofthemainmagneticpolecoreandtheexcitationwinding.Theironcoreisgenerallymadeof0.5mm～1.5mmthicksiliconsteelplatepunchedandriveted.Itisdividedintotwoparts:thepolebodyandthepoleshoe.Theshoe,thepoleshoeiswiderthanthepolebody,cannotonlyadjustthedistributionofthemagneticfieldintheairgap,butalsofacilitatethefixationoftheexcitationwinding.Thefieldwindingismadeofinsulatedcopperwireandsleevedonthecoreofthemainmagneticpole.Thewholemainmagneticpoleisfixedonthebasewithscrews.

(2)Reversingpole

ThefunctionofthereversingpoleistoimprovethecommutationandreduceThecommutationsparkthatmaybegeneratedbetweenthebrushandthecommutatorwhenthemotorisrunningisgenerallyinstalledbetweentwoadjacentmainmagneticpolesandconsistsofacommutatingpolecoreandacommutatingpolewinding.Thecommutatingpolewindingismadeofinsulatedwireandsheathedonthecommutatingpolecore,thenumberofcommutatingpolesisequaltothemainmagneticpole.

(3)Frame

Theoutershellofthemotorstatoriscalledtheframe.Themachinebasehastwofunctions:

Oneistofixthemainmagneticpole,thecommutatingpoleandtheendcover,andtosupportandfixtheentiremotor;

ThesecondisthemachineTheseatitselfisalsoapartofthemagneticcircuittoformamagneticpathbetweenthemagneticpoles.Thepartthroughwhichthemagneticfluxpassesiscalledtheyoke.Inordertoensurethatthemachinebasehassufficientmechanicalstrengthandgoodmagneticpermeability,itisgenerallymadeofcaststeelorweldedbysteelplates.

(4)Brushdevice

ThebrushdeviceisusedtointroduceordrawDCvoltageandDCcurrent.Thebrushdeviceiscomposedofabrush,abrushholder,abrushrodandabrushrodseat.Thebrushisplacedinthebrushholderandcompressedwithaspringtomakeagoodslidingcontactbetweenthebrushandthecommutator.Thebrushholderisfixedonthebrushrod,andthebrushrodismountedonthecircularbrushrodseat.Mustbeinsulatedbetween.Thebrushrodseatisinstalledontheendcoverortheinnercoverofthebearing,andthecircumferentialpositioncanbeadjusted,anditcanbefixedafteradjustment.

Rotor

(1)Armaturecore

Thearmaturecoreisthemainpartofthemainmagneticcircuit,andisusedtoembedDischargepivotwinding.Generally,thearmaturecoreislaminatedwithpunchedsheetsmadeof0.5mmthicksiliconsteelsheetstoreducetheeddycurrentlossandhysteresislossgeneratedinthearmaturecorewhenthemotorisrunning.Thelaminatedcoreisfixedontherotatingshaftortherotorsupport.Anarmatureslotisopenedontheoutercircleoftheironcore,andadischargearmaturewindingisembeddedintheslot.

(2)Armaturewinding

Thefunctionofarmaturewindingistogenerateelectromagnetictorqueandinducedelectromotiveforce,whichisthekeycomponentofDCmotorforenergyconversion,Soitiscalledanarmature.Itismadeupofmanycoils(hereinafterreferredtoascomponents)connectedaccordingtoacertainrule.Thecoilsaremadeofhigh-strengthenameledwireorglass-fiber-coatedrectangularcopperwire.Thecoilsidesofdifferentcoilsareembeddedinthearmatureslotintwolayers.Thecoresandthesidesoftheupperandlowercoilsmustbeproperlyinsulated.Inordertopreventthecentrifugalforcefromthrowingthecoiledgeoutoftheslot,theslotisfixedwithaslotwedge.Theterminalpartofthecoilprotrudingoutoftheslotisboundwithathermosettingnon-latticeglasstape.

(3)Commutator

InaDCmotor,thecommutatorisequippedwithbrushes,whichcanconverttheexternalDCpowersupplyintoanarmaturecoilThealternatingcurrentinthemediummakesthedirectionoftheelectromagnetictorqueconstant;intheDCgenerator,thecommutatorisequippedwithabrush,whichcanconvertthealternatingelectromotiveforceinducedinthearmaturecoilintopositiveandnegativebrushes.的DCelectromotiveforce.Thecommutatorisacylindercomposedofmanycommutatingsegments,andthecommutatingsegmentsareinsulatedbymicasheets.

(4)Rotatingshaft

Therotatingshaftservesasasupportfortherotationoftherotorandneedstohaveacertaindegreeofmechanicalstrengthandrigidity.Itisgenerallymadeofroundsteel.

Maincategories

DCgenerator

DCgeneratorisamachinethatconvertsmechanicalenergyintoDCelectricalenergy.ItismainlyusedastheDCmotorrequiredforDCmotor,electrolysis,electroplating,electricsmelting,chargingandexcitationpowersupplyofACgenerator.AlthoughwhereDCpowerisneeded,powerrectifiercomponentsarealsousedtoconvertACpowerintoDCpower,butfromsomeaspectsofperformance,ACrectifierpowercannotcompletelyreplaceDCgenerators.

DCmotor

ArotatingdevicethatconvertsDCelectricalenergyintomechanicalenergy.Thestatorofthemotorprovidesthemagneticfield,theDCpowersupplyprovidescurrenttothewindingsoftherotor,andthecommutatorkeepsthedirectionofthetorquegeneratedbytherotorcurrentandthemagneticfieldunchanged.Accordingtowhetherornotitisequippedwithacommonlyusedbrush-commutator,DCmotorscanbedividedintotwocategories,includingbrushedDCmotorsandbrushlessDCmotors.

ThebrushlessDCmotorisdevelopedinrecentyearswiththedevelopmentofmicroprocessortechnologyandtheapplicationofnewpowerelectronicdeviceswithhighswitchingfrequencyandlowpowerconsumption,aswellastheoptimizationofcontrolmethodsandlowcost,highmagneticenergylevel.AnewtypeofDCmotordevelopedbytheemergenceofthepermanentmagnetmaterial.

BrushlessDCmotorsnotonlymaintainthegoodspeedregulationperformanceoftraditionalDCmotors,butalsohavetheadvantagesofnoslidingcontactandcommutationsparks,highreliability,longservicelifeandlownoise.Numericalcontrolmachinetools,robots,electricvehicles,computerperipheralsandhouseholdapplianceshaveallbeenwidelyused.

Accordingtothedifferentpowersupplymethods,brushlessDCmotorscanbedividedintotwocategories:squarewavebrushlessDCmotors,whosebackEMFandpowersupplycurrentwaveformsarebothrectangularwaves,alsoknownasrectangularwavepermanentMagneticsynchronousmotor;sinewavebrushlessDCmotor,itsback-EMFwaveformandpowersupplycurrentwaveformarebothsinewaves.

Excitationmethod

Excitationmethodreferstothemethodofgeneratingamagneticfieldinarotatingmotor.TherearefourexcitationmethodsforDCmotors:

SeparatelyexcitedDCmotors

Thefieldwindinghasnoconnectionrelationshipwiththearmaturewinding,andtheDCmotorpoweredbyotherDCpowersupplytothefieldwindingiscalledseparately-excitedDCmotor,andpermanentmagnetDCmotorcanalsoberegardedasseparately-excitedorself-excitedDCmotor,Generallydirectlyreferredtoastheexcitationmethodispermanentmagnet.

Shunt-excitedDCmotor

Theexcitationwindingoftheshunt-excitedDCmotorisconnectedinparallelwiththearmaturewinding.Asashunt-excitedgenerator,theterminalvoltageemittedbythemotoritselfistheexcitationWindingpowersupply;asashunt-excitedmotor,thefieldwindingandarmaturesharethesamepowersource,whichisthesameasaseparately-excitedDCmotorintermsofperformance.

Series-excitedDCmotor

Afterthefieldwindingoftheseries-excitedDCmotorisconnectedinserieswiththearmaturewinding,itisconnectedtotheDCpowersupply.TheexcitationcurrentofthisDCmotoristhearmaturecurrent.

Compound-excitedDCmotor

Compound-excitedDCmotorhastwoexcitationwindings:parallelexcitationandseriesexcitation.Ifthemagnetomotiveforcegeneratedbytheserieswindingandthedirectionofthemagnetomotiveforcegeneratedbytheparallelwindingarethesame,itiscalledtheproductcompoundexcitation.Ifthetwomagnetomotiveforceshaveoppositedirections,itiscalleddifferentialcompoundexcitation.

DCmotorswithdifferentexcitationmethodshavedifferentcharacteristics.Ingeneral,themainexcitationmodesofDCmotorsareshuntexcitation,seriesexcitationandcompoundexcitation,andthemainexcitationmodesofDCgeneratorsareseparateexcitation,shuntexcitationandcompoundexcitation.

Modelnaming

DomesticmotormodelsgenerallyuseuppercaseEnglishChinesepinyinlettersandArabicnumerals,andtheformatis:thefirstpartusesuppercasepinyinletterstorepresenttheproductcode,andthesecondThepartusesArabicnumeralstoindicatethedesignserialnumber,thethirdpartusesArabicnumeralstoindicatethebasecode,andthefourthpartusesArabicnumeralstoindicatethearmaturecorelengthcode.

Workingprinciple

Aring-shapedpermanentmagnetisfixedinsidetheDCmotor.Thecurrentpassesthroughthecoilontherotortogenerateampereforce.Whenthecoilontherotorisparalleltothemagneticfield,itcontinuestorotateThedirectionofthemagneticfieldwillchange,soatthistime,thebrushattheendoftherotoralternatelycontactswiththeconversionpiece,sothatthedirectionofthecurrentonthecoilalsochanges,andthedirectionoftheLorentzforcegenerateddoesnotchange,sothemotorcankeeprotatinginonedirection.

TheworkingprincipleofaDCgeneratoristoconvertthealternatingelectromotiveforceinducedinthearmaturecoiltothecommutationeffectofthebrushbythecommutator,sothatitbecomesaDCelectromotiveforcewhenitisdrawnfromthebrushendprinciple.

Thedirectionoftheinducedelectromotiveforceisdeterminedbytheright-handrule(themagneticlineofinductionpointstothepalmofthehand,thethumbpointstothedirectionofmovementoftheconductor,andtheotherfourfingerspointtothedirectionoftheinducedelectromotiveforceintheconductor).

Thedirectionoftheconductor'sforceisdeterminedbytheleft-handrule.Thispairofelectromagneticforcesformsamomentthatactsonthearmature.Thismomentiscalledelectromagnetictorqueinarotatingelectricalmachine.Thedirectionofthetorqueiscounterclockwiseinanattempttomakethearmaturerotatecounterclockwise.Iftheelectromagnetictorquecanovercometheresistancetorqueonthearmature(suchasresistancetorquecausedbyfrictionandotherloadtorques),thearmaturecanrotateinacounterclockwisedirection.

Controlprinciple

ForthecontrolprincipleofbrushlessDCmotor,tomakethemotorrotate,thecontrolunitmustfirstaccordingtothepositionofthemotorrotorsensedbythehall-sensor,andthenaccordingtothestatorThewindingdeterminestheorderofturningon(orturningoff)thepowertransistorsintheinverter.Intheinverter,AH,BH,CH(thesearecalledupperarmpowertransistors)andAL,BL,CL(thesearecalledlowerarmpowertransistors)),sothatthecurrentflowsthroughthemotorcoilsinordertogenerateaforward(orreverse)rotatingmagneticfield,andinteractwiththemagnetoftherotor,sothatthemotorcanrotateclockwise/counterclockwise.Whenthemotorrotorrotatestothepositionwherethehall-sensorsensesanothersetofsignals,thecontrolunitturnsonthenextsetofpowertransistors,sothatthecirculatingmotorcancontinuetorotateinthesamedirectionuntilthecontrolunitdecidestostopthemotorrotorandturnoffthepowerTransistor(oronlyturnonthelowerarmpowertransistor);ifthemotorrotorisreversed,thepowertransistorturnsoninthereverseorder.

Basically,theopeningmethodofpowertransistorscanbeexemplifiedasfollows:AH,BLgroup→AH,CLgroup→BH,CLgroup→BH,ALgroup→CH,ALgroup→CH,BLgroup,butmustnotbeopenedintoAH,ALorBH,BLorCH,CL.Inaddition,becauseelectronicpartsalwayshavetheresponsetimeoftheswitch,theresponsetimeofthepartsshouldbetakenintoaccountwhenthepowertransistoristurnedoffandon.Otherwise,whentheupperarm(orlowerarm)isnotcompletelyclosed,thelowerarm(orupperarm)isalreadyTurningon,asaresult,theupperandlowerarmsareshort-circuitedandthepowertransistorisburnedout.

Whenthemotorrotates,thecontrolunitwillcomparethecommand(Command)composedofthespeedsetbythedriverandtheacceleration/decelerationratewiththespeedofthehall-sensorsignalchange(orcalculatedbysoftware)Thendecidebythenextgroup(AH,BLorAH,CLorBH,CLor...)theswitchisturnedon,andthelengthoftheturn-ontime.Ifthespeedisnotenough,thedrivewillbelonger,andthespeedwillbereducedifthespeedistoohigh.ThispartoftheworkisdonebyPWM.PWMisthewaytodeterminewhetherthemotorspeedisfastorslow.HowtogeneratesuchaPWMisthecoretoachievemoreprecisespeedcontrol.

High-speedspeedcontrolmustconsiderwhethertheCLOCKresolutionofthesystemissufficienttomasterthetimetoprocesssoftwareinstructions.Inaddition,thedataaccessmethodforhall-sensorsignalchangesalsoaffectstheprocessorperformanceandcorrectjudgmentAndreal-time.Asforthelow-speedspeedcontrol,especiallythelow-speedstart,thechangeofthereturnedhall-sensorsignalbecomesslower.Howtocapturethesignal,theprocessingtimingandtheappropriateconfigurationofthecontrolparametervalues​​accordingtothecharacteristicsofthemotorisveryimportant.Orthespeedreturnchangeisbasedontheencoderchangetoincreasethesignalresolutionforbettercontrol.Themotorcanrunsmoothlyandrespondwell,andwhethertheP.I.D.controlisappropriateornotcan'tbeignored.Asmentionedearlier,theDCbrushlessmotorisaclosed-loopcontrol,sothefeedbacksignalisequivalenttotellingthecontroldepartmenthowfarthemotorspeedisfromthetargetspeed.Thisisanerror.Knowingtheerror,itisnaturaltocompensate,andthemethodhastraditionalengineeringcontrolsuchasP.I.D.control.However,thecontrolstatusandenvironmentareactuallycomplexandchangeable.Ifyouwanttocontroltherobustnessanddurability,thefactorstobeconsideredmaynotbefullymasteredbytraditionalengineeringcontrol,sofuzzycontrol,expertsystemsandneuralnetworkswillalsobeincorporatedintointelligenttypes.TheimportanttheoryofPIDcontrol.