Page - 246 - in Emerging Technologies for Electric and Hybrid Vehicles
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Text of the Page - 246 -
Energies 2017,10, 616
Thesynthesizedcurrentvector is showninEquation(2):
is= √
2
3 (iA+ iB+ iC)= √
2
3 × 3
2 iej(ωst+φ1). (2)
It can be observed that the amplitude of the synthesized stator current vector is √
3/2 times
thatof thephasecurrent. IfwetakeaxisAasareferentialaxis, thespaceangleof thecurrentvector
correspondswith thephaseAcurrent in the timedomain. Instarandindependentmodes, the line
current of the inverter is the phase current and the current capacity imax is themaximumof the
phase current. In trianglemode, line currents i1, i2, and i3 andphase currents iA, iB, and iC have
therelationship:
i1= iA− iC, i2= iB− iA, i3= iC− iB. (3)
Accordingto this relationship,whenmotorsare insteadystate, thevectordiagramsof lineand
phasecurrents in the timedomainareasshowninFigure4.
6
S
Bi
Ai
Ci
1i2i
3i Ci
Figure4.Timedomainvectorof linecurrentandphasecurrent.
This indicatesthat, intrianglemode, theamplitudeofthelinecurrent is √
3timesthatof thephase
current insteadystate.Consequently,whenthecurrentcapacityof the inverter is imax, themaximum
of thephasecurrent in trianglemodeandthemaximumamplitudeof thesynthesizedstatorcurrent
vector is1/ √
3 times that instarandindependentmodes. Instar, independent,andtrianglemodes,
the relationships betweenmaximumamplitude of current vector ismaxY, ismaxD, and ismaxΔ are as
showninEquations (4)and(5):
ismaxY= ismaxD= √
6
2 imax (4)
ismaxΔ= √
6
2 × imax√
3 = √
2
2 imax. (5)
Limitationsonvoltageandcurrentvectorsdetermine theworkingrangesofeachwindingmode.
In star and trianglemodes, flux-weakening regions are not set. In independentmode, there are
non-flux-weakeningandflux-weakeningregions. Innon-flux-weakeningregions, if thestatorvoltage
increases to thesaturation threshold, themotorstartsworking in theflux-weakeningregiontoexpand
thespeedregulationrange. In thenon-flux-weakeningregionofeachwindingmode, themotor is
controlled by theMTPA (maximum torqueper ampere)method [25]. In flux-weakening regions,
themotor iscontrolledbythedirectfluxcontrolmethod.Basedonthepresentmotor’sangularvelocity
ωs, thealgorithmcalculates thespecificstator’smaximumflux,ψ∗s . Then,onthebasisof requested
torqueT∗e , axisdandq’sexpectedcurrent i∗d, i ∗
q areworkedout [26].
TheOW-PMSMdrivesystem’sparametersareshowninTable1; theexternalcharacteristic curves
controlledbytheabovecurrentstrategyaredemonstrated inFigure5.
246
Emerging Technologies for Electric and Hybrid Vehicles
- Title
- Emerging Technologies for Electric and Hybrid Vehicles
- Editor
- MDPI
- Location
- Basel
- Date
- 2017
- Language
- English
- License
- CC BY-NC-ND 4.0
- ISBN
- 978-3-03897-191-7
- Size
- 17.0 x 24.4 cm
- Pages
- 376
- Keywords
- electric vehicle, plug-in hybrid electric vehicle (PHEV), energy sources, energy management strategy, energy-storage system, charging technologies, control algorithms, battery, operating scenario, wireless power transfer (WPT)
- Category
- Technik