清华大学电子电机课程

Design&AnalysisforElectronicMachineSystemInstituteofPowerElectronicsandMotorControlTsinghuaUniversityZhengmingZhaoFeb.18,20011ChapterOne:Introduction1-1EvolutionofACElectricMachines1.DevelopmentofACelectricmachines

*Whatistheelectricmachine?

DeviceforelectromagneticconversionsTheoreticalbase:Maxwellelectromagnetictheory

(1850s)2MagneticsElectricityGeneratorElectricityMagneticsMotorElectricityMagneticsElectricityTransformerThreedevelopingways:

(1)DesignYearWeightCost

(p./hp)

(US$/hp)1890200180195722221976101019905.24.6*Reduced40times3(2)ModelingandSolution:1880-1910s:Classicalanalyticalelectromagneticfield1920s-1960s:Electricalcircuit--Park’sequation(double-axis)1970s-1980s:Numericalmethodforfieldequations(finiteelementanalysis,ANSYS)1980s-present:Combinationoffieldandcircuit

(3)ConstructionandMode:InductionSynchronousPMbrushlessDCSwitchedreluctance

4PMAxially-LaminatedSynchronousReluctanceMachine*Highpowerdensity*Highefficiencyandpowerfactor*Widespeedrange*Highreliability5PermanentMagnetMachines*Highefficiency*Highpowerfactor*Highreliability*Structurediversity6SwitchedReluctanceMachines*Highefficiency*Highfaulttolerance*Widespeedrange*Simplestructure7SwitchedReluctanceMachines8Cross-SectionofAnInductionMachine91-2WhatistheElectronicMachine?PowerSupplyElectricMachineLoadControllerElectronicMachineFourdevelopingtrends:*Integration:powerelectronics*Intelligence:fuzzy,neuro-network*Universal:universalmachinesystem*Information:communication,DSP,wireless101-3TheApplicationsofElectronicMachines*Lessthan3%inapplicationsDomesticApplicationsIndustrialApplicationsTraction/AutomotiveDefense/AerospaceApplicationsCommercialApplicationUtilityApplicationsIncreasingpower11ChapterTwo:GeneralandSpecialDesignFeaturesofElectronicMachines2.1DifferencesofElectronicandConventionalMachines12

MechanicalCharacteristicsofInductionMachineFivekeypoints:(1)RatedtorqueTn(2)StartingtorqueTs(3)MaximumtorqueTm(4)Stabilityarea(5)InstabilityareaTmTsTnInstabilityareaABC13MinimumSlipandMaximumEfficiency*Comparisonforthreetorque-speedcurvesasdifferentsupplyfrequencyandvoltage*Lossesandefficiencycurves14WithoutvectorcontrolWithvectorcontrolVectorControlforMotorDrive*D-axis:magnetizingaxis;Q-axis:torqueaxis*Constantfluxdensity*Idsforwholemagnetizingfield*Ir=IqrandIdr=015TypicalInverter-drivenInductionMotorSystemSwitch(IGBT)RectifierPWMController

InductionMotorLoadTrianglecarrierSinusoidalReference16Pulse-Width-Modulation(PWM)andHarmonics*Vref>Vtri,switchison*Vref<Vtri,switchisoff*Thefundamentalcomponentof

theoutputphasevoltageissinusoidalbase*Therearelotsofharmonics

1718QuestionandDiscussion1.What’stheelectronic

machinesystem?2.Whataredifferencesbetweentheelectronicandconventionalmachines?192.2DesignFreedomandStrategies(1)ConventionalDesignStrategiesa.Fulfillneededstart-upcharacteristics(50%)Requirements: *Limitinrushcurrent *Generatehighstartingtorque *Ensurehighstartingefficiency *Eliminateharmonicsb.Provideappropriatesteadystatecharacteristics(efficiency,powerfactor,andsoon)(30%)c.Permiteasyandeconomicproduction(20%)20(2)Inverter-drivenDesignStrategiesa.Twofreedoms:*Completelyabandonstart-upcurrent,torqueandefficiencywith

fixedfrequency*Don’tcareabnormalharmonicstorqueatthetimeofstartingb.Threevaluablebenefits:*Maximumefficiencyandimprovedpowerfactorareintroducedintosizingequation*Theshapeofrotorslotcanbemostsuitabledesigned*Theconstraintconditionsofmatchofstatorandrotorslotnumber

canbeeliminated21DesignofmaindimensionsSelectionofairgaplengthStatorwindingsdesignStatorslotdesignstatorouterdiameter

RotorwindingsdesignRotorslotdesignRotorinnerdiameterFluxdensityLinecurrentdensityL/Di1RelatedparameterswithstatorcurrentdensityRelatedparameterwithstatorfluxdensityRelatedparameterswithstatorcurrentdensityRelatedparameterwithstatorfluxdensityMachineDesignFlowChart222.3SizingEquationforMachineDesign2.3.1SizingequationforconventionalmachinedesignFiveequations:

(1)Back-emfequation:(2)Outputpowerequation:(3)Fluxequation:(4)Surfacecurrentdensityequation:(5)Polepitchequation:23Dil:statorinteiraldiameterL:effectivelengthofstatorBg:

fluxdensityinairgapP:

ratedoutputpowerns:ratedspeedC:

machineconstant:efficiencycos:ratedpowerfactorKe:

back-emfcoefficientKw:

windingcoefficientA:surfacecurrentdensityConventionalSizingEquation242.3.2SizingEquationforElectronicMachines(1)Frequencyequation:Statorcurrentdensityequation:Slotareaofstator:Roundslotarea:25SizingEquationforElectronicMachines(2)Fluxdensityequationsinparts:FluxdensityinairgapFluxdensityinteethFluxdensityincoreKs:fluxcoefficient26SizingEquationforElectronicMachines(3)Ratioofareasincopperandslot:27SizingEquationforElectronicMachines(4)Statorslotarea:28SizingEquationforElectronicMachines(5)29SizingEquationforElectronicMachines(6)Finalsizingequation:Features:(1)Outerdiameterasvariable(2)Outputfunctioninsteadof

machineconstantCurvesfordifferenta,bandc30HomeworkI

Fromthefollowingequations,

Derivetheequation:Andexplainitsphysicalmeaning.and31RotorSlotDesign1.RotorslotshapeThreekeypoints:slotshape,slotnumber,slotdimensionsTwomainslotshapes:

RoundbottomFlatbottom32

Rotorshapeforconventionalinductionmotor*Itiscommontoadoptadoublecageordeepbarstoincreasetheskineffectforlargerotorresistanceduringstartingandhighstartingtorque.DoublecageDeepbarStartingtorque(s=1):33

rb:nominalrotorresistancewithoutconsiderationofskineffect

lb:lengthoftherotorconductorle:effectivelengthoftherotorcore

kr:acoefficientaccountingforskineffecthb:theheightofrotorconductorbb:thewidthofrotorconductorbr:thewidthofrotorslotSF:slipfrequency

r:rotorconductorconductivityEffectiveRotorResistance

34RotorSlotLeakageReactance*Therelationoftherotorslotleakagepermeance

rtotheshapeof

therotorslotfeaturedbyh/b2andb1/b2isshownastheFig.*Adeepslot(h/b2>2)withatip-uptriangularshape(b1/b2<0.6)

hasaverylargerandincreasestherotorleakagereactance.*Withoutconsiderationsofthe

startingcharacteristics,therotor

slotcanbewiderandshorter(h/b2<1.5andb1/b2>0.9)

underthelimitationoftheflux

densityinrotorteeth.35*Thisresultsinamuchreducedrotorleak