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Energies 2017,10, 616
1
1
2 dc
V
1
1
2 dc
V 2
1
2 dc
V
2
1
2 dc
V
Amu
Bmu
Cmu
nmu
Figure2.Schematicdiagramofmid-pointvoltage.
1
2 dc
V
1
2 dc
V
1
2 dc
V dcV
dcV 1 2
2
dc
dcV
V 1 2
2
dc
dcV
V
1 2
2
dc
dcV
V
(a) Star mode (b) Triangle mode (c) Independent mode
Figure3.Synthesizingvoltagevectorofeachwindingmode.
Theamplitudesofbasicvoltagevector instar, triangle,andindependentmodesusbY,usbΔ and
usbD canbeobtainedfromFigure3as √
2/3Vdc, √ 2/3×√3Vdc, and √
2/3(Vdc1+Vdc2), respectively.
In these equations, √
2/3 is the equal-power conversioncoefficient. Wecansee thatwhen thebus
voltage isVdc, theamplitudeof thebasicvoltagevector in trianglemode is √
3 times that instarmode.
In independentmode,whenbusvoltageVdc1=Vdc2=Vdc, theamplitudeof itsbasicvoltagevector is
twice that instarmodeand2/ √
3 times that in trianglemode. Ithas tobenotedthat theabovebasic
voltagevectorsaredistributedwithanπ/3angle interval, and ineachwindingmodetherearesix
equal-amplitudebasicvoltagevectors formingavoltagevectorhexagon in themotorvectorplane.
It is likely thatvoltagevectormaynotequal theamplitudeofahexagonvertex’svoltagevector inany
angle.Hence, theamplitudeof thevoltagevector in themotor’sappropriate linear range is supposed
tobe theradiusof the inscribedcircleofahexagon √
3/2times theamplitudeofbasicvoltagevectors
when the switch status are as above. Then, themaximumamplitudeof the voltage vector at any
angle instar, triangle, andindependentmodesusmaxY,usmaxΔ, andusmaxD are:Vdc/ √
2, √
6Vdc/2,and
(Vdc1+Vdc2)/ √
2, respectively.
Nowwewilldiscuss the stator current’s limitationsonwindingmodes. Becauseofwindings’
inductancecharacteristics, thephasecurrentof themotorhas inertiaandcannotabruptlychange like
voltage. Therefore, insteadystate, thewaveformsof the three-phasecurrent in the timedomainare
equal-amplitudesinusoidwith2π/3phasedifference. Three-phasecurrentvectorsaredemonstrated
inEquation(1): ⎧⎪⎨
⎪⎩ iA= icos(ωst+φ1)ej0
iB= icos(ωst+φ1− 2π3 )ej 2π
3
iC= icos(ωst+φ1− 4π3 )ej 4π
3 . (1)
245
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