permanent magnet synchronous generators-

pmsg ppt

1. Content

2. Introduction
•Thepermanentmagnetsynchronousgeneratorcalledsobecauseinthissynchronousgenerator
excitationisprovidedwiththepermanentmagnetinsteadoftheexternalexcitationsource.
•Itsrotorisconsistsofthepermanentthatgeneratesafieldforexcitationandreplacestheexternal
supplysourceforthegenerator.
•Inmostofgenerationpowerplants,thesynchronousgeneratorisused.Insteamturbines,hydro
turbines,andingasturbinessynchronousgeneratorisused.
•Likeothergenerators,thephysicalstructureofthisgeneratoristhesameitalsoconsistsoftherotor
whichalsocomprisesofthepermanentmagnetwiththeshaftconnectedwithit.
•Likestatorofothergenerators,thisgeneratoralsohasastatorthatprovidesprotectiontointernal
structurefromtheexteriorenvironment.
•Inpermanentsynchronousgenerator,thereisnoneedoftheslipringsandcarbonbrushes,which
makethemachinelessexpensive,lightweight,andmaintenanceofthegeneratoralsodecreases.

3. •Butinhighratinggenerators,largesizegeneratorsareusedthatmakemachines
somewhatexpensiveandincreasestheprice.
•Thegeneratorattachedwiththepowerelectronicconversioncircuitrycanworkonthe
lessspeedandsothereisnoneedofthegearbox.
•Thepresenceofgearboxesincreasestheprice,energylosses,andcostofrepairing
thegeneratorbutwithoutthegearboxpriceandweightofcircuitrydeceasesbutitalso
thebestoptionfortheoffshoreapplications.
•Withthedirectionoffluxlines,thepermanentsynchronousgeneratorisdividedinto
threecategoriesfirstoneistheradialfluxpermanentmagnetsynchronousgenerator,
thesecondoneistheaxialfluxpermanentmagnetsynchronousgeneratorandthethird
oneisthetransversefluxpermanentsynchronousgenerator.

4. Permanent MagnetTechnology
•The use of permanent magnets (PMs) in construction of
electrical machines
•brings the followingbenefits:
No electrical energy is absorbed by the field excitation
system and thus there are no excitation losses which means
substantialincrease in theefficiency,
Higher torque and/or output power per volume than
whenusing electromagneticexcitation,
Better dynamic performance than motors with
electromagnetic
•excitation (higher magnetic flux density in the airgap),
Simplification of construction andmaintenance,
Reduction of prices for some types ofmachines.

5. ApplicationsofPermanentSynchronousGenerator
•Thesearesomeapplicationsofthepermanentmagnetsynchronous
generator.
•Itusedtoprovidethepowerfortheexcitationofthehighratingsynchronous
generator.
•Duringtheshortcircuit,thesegeneratorsprovidethepowertothegenerator
connectedinthesystemtomaintaintherequiredvoltageforthesystem.
•Italsousedinsuchpowergenerationsystemswherewindturbinesareused.

6. Permanent MagnetClassification
PermanentMagnet
Synchronous
Machine(PMSG)
Permanent
Magnet
PermanentMagnet
BrushlessMachine
(BLDC)

7. Permanent MagnetClassification

8. Introduction
PM Synchronous Machine are widely usedin
Wind milegeneration
Industrial servo-applications due to its high-performancecharacteristics.
Generalcharacteristics
Compact
High efficiency (no excitationcurrent)
Smoothtorque
Low acousticnoise
Fast dynamic response (both torque andspeed)
Expensive

9. Construction
PMSM
Stator Rotor
Radial Flux&
AxialFlux
Inner Rotor&
OuterRotor
Longitudinal&
Transversal

10. Radial & AxialRotor
Ifthenormalvectorisperpendicularto
axis,machineiscalledRadial.Ifthe
normalvectorisparallelwiththeaxis,the
machineiscalledAxial.
RadialRotor
Higherpowerratingachievedby
increasing the length ofmachine.
Used in
Shippropulsion
Robotics
Traction
Windsystems

11. Radial & AxialRotor
AxialRotor
Smaller than Radialmachine
High torquedensity
Usedin
Gearless elevatorsystems
Rarely used inTraction
Generation

12. Longitudinal & TransversalRotor
Intransversalfluxmachines,the
planeoffluxpathisperpendicularto
thedirectionofrotormotion.
Transversalfluxmachinescanbe
adjustedindependentlycurrent
loadingandthemagneticloading.
Usedin
Applicationswithhightorque
densityrequirement.
Freepistongeneratorsforhybrid
vehicles.
Ship propulsion and windsystem.

13. Inner and OuterRotor

14. InnerRotor
Theinterior-magnetrotorhasradially
magnetizedandalternatelypoledmagnets.
Becausethemagnetpoleareaissmaller
thanthepoleareaattherotorsurface,the
airgapfluxdensityonopencircuitisless
thanthefluxdensityinthemagnet.
Themagnetisverywellprotectedagainst
centrifugalforces.Such adesignis
recommendedforhighfrequencyhigh
speedmotors.

15. OuterRotor
Thesurfacemagnetmotorcanhave
magnetsmagnetizedradiallyorsometimes
circumferentially.An externalhigh
conductivitynon-ferromagneticcylinderis
sometimesused.ItprotectsthePMsagainst
thedemagnetizingactionofarmature
reactionandcentrifugalforces,providesan
asynchronousstartingtorque,andactsasa
damper.
Themagnetisverywellprotectedagainst
centrifugalforces.Such adesignis
recommendedforhighfrequencyhigh

16. PMConfiguration
PM
(Permanent
Magnet)
Surface
Magnet
InsetMagnet
BuriedMagnet

17. Surface and BuriedMagnet
•SurfaceMagnets
Simpleconstruction
Small armature reactionflux
Permanent magnetsnot
•protected against armaturefields
Eddy-current losses in
permanent magnets
Expensivedamper
BuriedMagnets
Relativelycomplicated
construction
High armature reactionflux
Permanent magnetsprotected
against armaturefields
No eddy-current losses in
permanentmagnets
Less expensivedamper

18. Permanent magnet B-Hcurve

19. OperatingPrinciple
Inthepermanentmagnetsynchronous
generator,themagneticfieldisobtainedby
usingapermanentmagnet,butnotan
electromagnet.Thefieldfluxremains
constantinthiscaseandthesupplyrequired
toexcitethefieldwindingisnotnecessary
andslipringsarenotrequired.
Alltheotherthingsremainthesameas
normalsynchronousgenerator.
TheEMFgeneratedbyasynchronous
generatorisgivenasfollows

20. EquivalentCircuit– rotorside
Voltage Equation of PM machine in rotorreference

21. EquivalentCircuit– rotorside
Fig: PM equivalent for d-axis &q-axis

22. EquivalentCircuit– rotorside
Flux Linkageequations
The Flux Linkage can be generated fieldcurrent

23. VectorDiagram
Stator referenceaxis
X-Yaxis
Rotor referenceaxis
d-qaxis