Six-Phase Electric Machines

124 Pages·2018·4.181 MB·English

by  Jonas Juozas Buksnaitis

Jonas Juozas Buksnaitis
Six-Phase
Electric Machines
Six-Phase Electric Machines
Jonas Juozas Buksnaitis
Six-Phase Electric Machines
JonasJuozasBuksnaitis
InstituteofEnergeticsandBiotechnology
AleksandrasStulginskisUniversity
Kaunas,Lithuania
ISBN978-3-319-75828-2 ISBN978-3-319-75829-9 (eBook)
https://doi.org/10.1007/978-3-319-75829-9
LibraryofCongressControlNumber:2018935278
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Preface
Inthefivechaptersofthemonograph,Six-PhaseElectricMachines,acomprehensive
description of the following material is presented: (a) research on the harmonic
spectrum of magnetomotive forces generated by the six-phase windings, methods
of their development, and methods of analysis of electromagnetic properties of
such windings (Chap. 1); (b) creation of electrical diagrams of the single-layer
six-phase concentrated, preformed, concentric, and chain windings, and an inves-
tigation and evaluation of electromagnetic properties of these windings (Chap. 2);
(c) creation of electrical diagrams of the two-layer preformed and concentric
six-phase windings, investigation and evaluation of electromagnetic properties of
such windings (Chap. 3); (d) creation of electrical diagrams of the two-layer
preformed fractional-slot six-phase windings, investigation and evaluation of
electromagnetic properties of such windings (Chap. 4); (e) determination and
comparison of electromagnetic and energy-related parameters of a factory-made
motor with a single-layer preformed three-phase winding, and a rewound motor
with a single-layer preformed six-phase winding (Chap. 5).
In this monograph, the author performed a comprehensive analysis of different
types of six-phase windings, as well as the theoretical investigation of related
electromagneticparameters;thisinvestigationwasalsousedasabasistocomplete
thequalitativeevaluationofelectromagneticcharacteristicsofdiscussedwindings.
Themonographisintendedasaprofessionalbook,dedicatedtothespecialistsin
thefieldofelectricalengineering,andcouldbeusedtodeepentheirknowledgeand
applyitinpractically.Materialcanbealsousedasasourceofscientificinformation
inmaster’sanddoctoralstudies.
v
vi Preface
The author isfully aware that he was unable to avoid all potential inaccuracies.
SomewereeliminateduponconsultingLithuanianspecialistsofelectricalengineer-
ing. Additionally, the author wishes to express his gratitude to everyone who
contributedtothemanuscriptpreparation.
Kaunas,Lithuania JonasJuozasBuksnaitis
Introduction
In the second half of the nineteenth century, when a direct current machine was
alreadyavailable,itwasgenerallyassumedthatthealternatingcurrent,whoseflow
direction and magnitude change many times per second, would not be practically
applied, and that there was no need for AC generators that create such electrical
current.EvengreatscientistssuchasMichael Faradayhadsuchanopinion.He,after
receiving two anonymous projects of synchronous generators – one with an open
magneticcircuitandanotherwithaclosedone–didnotpublishanyworksrelatedto
theseconceptsforalongtime.Faradaywasconvincedthattheseprojectswerenot
valuable, despite the second project essentially being a prototype of the modern
synchronousgenerator.
Nevertheless, many scientists and inventors realized that sources of alternating
current are simpler and more reliable. Consequently, by the end of the nineteenth
century, significant research had been carried out on single-phase, two-phase, and
three-phasealternating currentsystems.The rotatingmagneticfieldofatwo-phase
windingwasdiscoveredbytwoindependentlyworkingscientists:FerrarifromItaly,
andTeslafromformerYugoslavia,whoworkedandlivedforthemostpartofhislife
inUSA.Bothscientistspublishedtheseworksin1888.Todemonstratetherotating
magneticfield,amodelofatwo-phaseinductionmotorwasconstructed.Afterthis
discovery, adoption of three-phase electrical current devices became widespread.
This adoption was encouraged by Dolivo-Dobrovolsky developing a three-phase
generator in 1888, an induction motor with a cage-type rotor in 1889, and a
transformerin1890whileworkingattheAEGCompany.Thiswasfurtherenhanced
bythedemonstrationofthefirst170-kmthree-phaseelectricitytransmissionlinein
1891.
Foralongtime,itwasbelievedthatthethree-phasevoltagesystemoptimallymet
theneedsofallconsumersofelectricalenergy.Therefore,itwasonlyafterabouta
century had passed that research on various theoretical and experimental studies
using four-phase and five-phase alternating-current electrical began. However, no
vii
viii Introduction
anypositiveresultsofpracticalsignificancewereachievedwiththesephasenumbers
ofalternatingcurrent.
Thesix-phasevoltagesystemwasfirstintroducedincurrentrectificationcircuits,
as the increase in the number of phases significantly reduces ripples in electrical
currents.Bythetwenty-firstcurrents. Thisvoltagesystemisincreasinglybeingused
in the research of different operation modes of multiphase alternating-current elec-
trical machines [11–17]. In scientific works, Investigations on six-phase induction
motors with symmetric and asymetric stator windings have been carried out with
motors provided by multiphase inverters. Some studies using six-phase asynchro-
nous and synchronous generators have also been performed. Most of these works
dealwithaspectsofcontrolofsix-phaseelectricalmachines.Thecompletedstudies
revealthattherearesomeadvantagesofsix-phaseelectricalmachinesagainstthree-
phase machines. However, the process of creation of six-phase windings and
parameters of the investigated electrical machines were not explored sufficiently,
nor have the electromagnetic properties of such windings. In completed studies,
there is also a lack of comparison of energy-related parameters of six-phase
machinesversussimilarparametersofthree-phasemachines.
Thecurrentworkanalyzestheformationofvarioustypesofsix-phasewindings
and present their parameters. It also calculates the electromagnetic efficiency and
winding factorsinorder tocomparethem totherelated factorsinanalogous three-
phasewindings.
Contents
1 GeneralSpecificationofSix-PhaseWindings
ofAlternatingCurrentMachines. . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 HarmonicSpectrumofMagnetomotiveForceGenerated
bytheSix-PhaseCurrentSystem. . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Six-PhaseVoltageSourcesandPeculiaritiesofConnecting
ThemtoSix-PhaseWindings. . . .. . .. . . .. . . .. . . .. . . .. . . .. 7
1.3 GeneralAspectsofSix-PhaseWindings. . . . . . . . . . . . . . . . . . . . 11
1.4 EvaluationofElectromagneticProperties
ofSix-PhaseWindings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.5 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2 ResearchandEvaluationofElectromagneticProperties
ofSingle-LayerSix-PhaseWindings. . . . . . . . . . . . . . . . . . . . . . . . . 23
2.1 ConcentratedSix-PhaseWindings. . . . . . . . . . . . . . . . . . . . . . . . 23
2.2 PreformedandConcentricSix-PhaseWindings
withq¼2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.3 Six-PhaseChainWindingswithq¼2. . . . . . . . . . . . . . . . . . . . . 33
2.4 PreformedandConcentricSix-PhaseWindings
withq¼3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.5 Six-PhaseChainWindingswithq¼3. . . . . . . . . . . . . . . . . . . . . 43
2.6 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3 ResearchandEvaluationofElectromagneticProperties
ofTwo-LayerSix-PhaseWindings. . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.1 Two-LayerPreformedSix-PhaseWindingswithq¼2. . . . . . . . . 49
3.2 MaximumAveragePitchTwo-LayerConcentricSix-Phase
Windingswithq¼2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.3 ShortAveragePitchTwo-LayerConcentricSix-Phase
Windingswithq¼2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
ix
x Contents
3.4 Two-LayerPreformedSix-PhaseWindingswithq¼3. . . . . . . . . 62
3.5 MaximumAveragePitchTwo-LayerConcentricSix-Phase
Windingswithq¼3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
3.6 ShortAveragePitchTwo-LayerConcentricSix-Phase
Windingswithq¼3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
3.7 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
4 ResearchandEvaluationofElectromagneticProperties
ofTwo-LayerPreformedFractional-SlotSix-PhaseWindings. . . . . 81
4.1 Two-LayerPreformedSix-PhaseWindingswithq¼1/2. . . . . . . . 81
4.2 Two-LayerPreformedSix-PhaseWindingswithq¼3/2. . . . . . . . 84
4.3 Two-LayerPreformedSix-PhaseWindingswithq¼5/2. . . . . . . . 88
4.4 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
5 InvestigationandComparisonofThree-Phase
andSix-PhaseCageMotorEnergyParameters. . . . . . . . . . . . . . . . . 93
5.1 ResearchObject. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.2 EvaluationofParametersofSingle-LayerPreformed
Six-PhaseWinding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
5.3 CageMotorResearchResults. . . . . . . . . . . . . . . . . . . . . . . . . . . 98
5.4 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Bibliography. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . 107
Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109