Reduction of Audible Noise of a Traction Motor at PWM Operation

40 Pages·2017·1.39 MB·English

Reduction of Audible Noise of a Traction
Motor at PWM Operation
Hanna Amlinger
LicentiateThesis
Stockholm,Sweden
2018
Academic thesis with permission by KTH Royal Institute of Techno-
logy, Stockholm, tobesubmittedforpublicexaminationforthedegree
of Licentiate in Vehicle and Maritime Engineering, Tuesday the 6th of
February, 2018 at 13.00, in E2, Lindstedsvägen 3 (floor 3), KTH - Royal
InstituteofTechnology,Stockholm,Sweden.
ISBN978-91-7729-649-2
TRITA-AVE2017:93
ISSN1651-7660
(cid:13)c HannaAmlinger,2018
Postaladdress: Visitingaddress: Contact:
KTH,AVE Teknikringen8 [email protected]
SE-10044Stockholm Stockholm
ii
Abstract
Adominatingsourcefortheradiatedacousticnoisefromatrainatlow
speedsisthetractionmotor. Thisnoiseoriginatesfromelectromagnetic
forcesactingonthestructureresultinginvibrationsonthesurfaceand
thus radiated noise. It is often perceived as annoying due to its tonal
nature. Toachieveadesirableacousticbehavior,andalsotomeetlegal
requirements, it is of great importance to thoroughly understand the
generation of noise of electromagnetic origin in the motor and also to
beabletocontrolittoalowlevel.
Inthiswork,experimentaltestshavebeenperformedonatractionmo-
tor operated from pulse width modulated (PWM) converter. A PWM
converteroutputsaquasi-sinusoidalvoltagecreatedfromswitchedvolt-
age pulses of different widths. The resulting main vibrations at PWM
operationandtheircauseshavebeenanalyzed. Itisconcludedthatan
appropriateselectionofthePWMswitchingfrequency,thatistherateat
whichthevoltageisswitched,isapowerfultooltoinfluencethenoiseof
electromagneticorigin. Changingtheswitchingfrequencyshiftsthefre-
quenciesoftheexcitingelectromagneticforces.Furtherexperimentalin-
vestigationsshowthatthetrendisthattheresultingsoundpowerlevel
decreaseswithincreasingswitchingfrequencyandeventuallythesound
power level reaches an almost constant level. The underlying physical
phenomenaforthereducedsoundpowerlevelisdifferentfordifferent
frequencyranges. Itisproposedthatthetractionmotor,similartoathin
walled cylindrical structure, shows a constant vibration over force re-
sponseaboveacertainfrequency. Thisisinvestigatedusingnumerical
simulations of simplified models. Above this certain frequency, where
theareaofhighmodaldensityisdominating,thenoisereducingeffect
offurtherincreasingtheswitchingfrequencyislimited.
Keywords: electromagnetic noise, pulse width modulation (PWM),
switchingfrequency,tractionmotor
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Sammanfattning
Traktionsmotornärenstarktbidragandekällatillljudetfrånetttågvid
låga hastigheter. Elektromagnetisk krafter i motorn verkar på dess yta
såattdennavibrerarvilketresulterariutstrålatljud.Dettaljuduppfat-
tasoftasomirriterandeeftersomattdetärväldigttonalt.Förattminska
det utstrålade ljudet från motorn samt för att uppfylla lagkrav, är det
väldigtviktigtattförstådebakomliggandetorsakernatillhurljudfrån
elektromagnetiska krafter uppkommer och även att kunna kontrollera
dettaljudtillenlågnivå.
I detta arbete har experiment utförts på en traktionsmotor matad från
enpulsbreddsmodulerad(PWM)frekvensomriktare.EnPWMomrikta-
re genererar en sinusliknanade spänning utifrån switchade spännings-
pulser av olika bredd. De dominerande vibrationerna vid PWM mat-
ning och dess bakomliggande orsaker har analyserats. Ett lämpligt val
avPWMswitchfrekvens,dvs.hursnabbtspänningenswitchas,ärettef-
fektivt sätt att påverka ljudet som uppkommer från elektromagnetiska
krafter. När switchfrekevensen ändras, ändras de exciterande elektro-
magentiska krafternas frekvens. Ytterligare experimentella mätningar
visar att trenden är att ljudtrycket minskar med ökad switchfrekvens
och till slut når ljudtrycket en nästan konstant nivå. De bakomliggan-
defysikaliskaorsakernatillminskningenavljudtrycketärolikaföroli-
ka frekvensområden. En hypotes är att traktionsmotorn, likt en tunn-
väggigcylinder,harettkonstantförhållandemellanresulterandevibra-
tionochexciterandekraftöverenvissfrekvens.Dettastuderasnärma-
regenomnumeriskasimuleringaravförenklademodeller.Dettaskulle
betyda att över denna frekvens, i området som domineras av hög mo-
daltäthet,äreffektenavattökaswitchfrekvensenytterligaremedavsikt
attreduceraljudetbegränsad.
Nyckelord:elektromagnetisktljud,pulsbreddsmodulering,switchfrek-
vens,traktionsmotor
iv
Acknowledgements
Firstofall,IwouldliketothatTheKTHRailwayGroupandBombardier
Transportationforthefinancialsupportofthisresearch.
TomysupervisorsInesLopesArteagaandSivLeth-thankyoubothfor
allyoursupport,encouragement,feedbackanddiscussionsduringthis
work!
I would also like to thank all present and former colleagues at Bom-
bardier: mycolleaguesattheControlDynamicsdepartmentalwaysan-
swering all my questions related to converter control and all acousti-
cianswithintheCenterofCompetenceAcousticshelpingoutwithques-
tionsrelatedtoacousticsandacousticmeasurements. Aspecialthanks
to Fredrik Botling with whom I shared a large part of this journey for
thegoodcollaboration,toFloreneceMeierforalltheinterestingdiscus-
sionsandallyourvaluableinputandfeedback; andtoDanielJansson,
MattiasHillandTommySigemoforallthehelpwithmeasurements.
ThankyoutoallcolleaguesatKTH,eventhoughIhavenotbeenatKTH
veryoftenyouhavealwaysmademefeelverywelcome!
Lastbutnotleast,toallmylovingfriendsandfamily,withoutyouthis
would never have been possible. Karin, Fredrik and especially Lina:
it has been so valuable to share my thoughts with someone who has
alreadybeenonasimilarjourney,thankyouforalwaysbeingthereand
listeningandcheering! Christoffer,thankyouforyourendlessloveand
support;andLinnea,thereisnobodyornothingthatremindsmewhat
itisreallyimportantinlifethewayyoudo-Iloveyou!
HannaAmlinger
Västerås,January2018
v

Dissertation
This thesis consists of two parts: The first part gives an overview of
the research area and work performed. The second part contains the
followingresearchpapers(A-B):
PaperA
H.Amlinger,F.Botling,I.L.Arteaga,andS.Leth,“OperationalDeflec-
tionShapesofaPWM-fedTractionMotor,”inRotatingMachinery,Hybrid
TestMethods,Vibro-Acoustics&LaserVibrometry,Volume8: Proceedingsof
the34thIMAC,AConferenceandExpositiononStructuralDynamics2016,
J.DeClerckandD.S.Epp,Eds. SpringerInternationalPublishing,2017,
pp. 209-217.
PaperB
H.Amlinger,I.L.Aretaga,andS.Leth,“ReductionofRadiatedAcoustic
NoiseofaTractionMotoratPWMConverterOperation”,submittedto
IEEETransactionsonIndustryApplications(January2018).
Divisionofworkbetweenauthors
H.Amlingerinitiatedthedirectionofandperformedthestudies,made
the analysis, and produced the papers. I. Lopez Arteaga and S. Leth
supervisedthework,discussedideasandreviewedthework.
vii
Publicationsnotincludedinthisthesis
Conferencepapers:
H. Amlinger, I. L. Aretaga, and S. Leth, “Impact of PWM Switching
Frequency on the Radiated Acoustic Noise from a Traction Motor,” in
Proceedings of the 20th International Conference on Electrical Machines and
Systems(ICEMS),2017,Sydney,Australia. Available: IEEEXplore.
F.Botling,H.Amlinger,I.L.Arteaga,andS.Leth,“Vibro-AcousticModal
Model of a Traction Motor for Railway Applications,” in Rotating Ma-
chinery, Hybrid Test Methods, Vibro-Acoustics & Laser Vibrometry, Volume
8: Proceedingsofthe34thIMAC,AConferenceandExpositiononStructural
Dynamics 2016, J.De Clerck and D.S.Epp, Eds. Springer International
Publishing,2017,pp. 197-208.
viii
Contents
I OVERVIEW 1
1 Introduction 3
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Thesisoutline . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Acousticnoiseofelectromagneticoriginintractionmotors 9
2.1 Pulsewidthmodulation . . . . . . . . . . . . . . . . . . . . 9
2.2 Electromagneticforces . . . . . . . . . . . . . . . . . . . . . 12
3 Summaryofappendedpapers 19
3.1 PaperA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.2 PaperB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4 Conclusions 23
Bibliography 25
II APPENDEDPAPERSA-B 29