Seite - 248 - in Emerging Technologies for Electric and Hybrid Vehicles
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Energies 2017,10, 616
Undermost circumstances, thedifferencesbetweenboth sides’DCbusvoltageare small and
thehighest rotaryspeedsof themotor in thenon-flux-weakeningregion, triangleandindependent
mode increase in theordernmY<nmΔ<nmD. Inaccordancewith this inequality,wedefineswitching
fromstarmodeto trianglemode, fromtrianglemodeto independentmode,andfromstarmodeto
independentmodeasupswitching; switchingfromindependentmodeto trianglemode, fromtriangle
modetostarmode,andfromindependentmodetostarmodearedownswitching.
Wewill beginwith theupswitchingstrategy. Duringmotorworkingperiod,parameters such
asmagnetfluxandinductancefluctuatebecauseof rising temperature, followedbyfluctuationsof
workingrangesofeachwindingmode. Toavoidfrequentswitchingwhentheworkingpointof the
motorfluctuates, this paper proposes an algorithm to judge the saturation state of torque. When
judgedaspositive,upswitching is triggeredtoensure theaccuracyof theswitchingboundary.
This algorithm functionsduring theprocess of torque increasing fromzero to themaximum.
It calculateswhen the expected torque is at amaximum, the timeperiod tint duringwhich torque
increases fromzero to themaximumat this specificrotaryspeedin thecurrentwindingmode(staror
triangle)as integration timeandintegrationofabsolute torqueerrorΔT (thedifferencebetweenactual
torqueTl andexpectedtorqueT∗e )as threshold Ith in thisprocess. Then, it calculates integration Iof
absoluteactual torqueerrorΔT from tint to thepresentandcompares itwith integration threshold
Ith. If I≥ Ith, then themotor’s torque isalmost saturatedanddoesnotmatch theexpected torque.
Thisalgorithmisbasedonwhether theoutput torqueagreeswith theexpectedtorque inaparticular
periodtoeliminateuncertainties in thewindingmodes’workingrangebecauseoffluctuations in the
motor’sparameters.
Voltageequationsofmotor indqcoordinationareexpressed inEquations (6)and(7):
ud=Rsid+Ld did
dt −ωrLqiq (6)
uq=Rsiq+Lq diq
dt +ωr(Ldid+ψf). (7)
Electromagnetic torque isshowninEquation(8):
Te= p0iq[ψf+(Ld−Lq)id]. (8)
Fromtheaboveequations,wecantell thatelectromagnetic torqueTe ismainlydeterminedbyaxis
q’scurrent iq; thesmaller the inductancedifferencebetweenaxisdandq, thebigger theshare that iq
determines.WhenLd=Lq=Ls themotor issurface-mounted;MTPAcontrol is id=0control. For the
sakeof simplifyingcalculations, the integration timeof torque tint isderivedas id= 0control, and
whenthedifferencebetweenLd andLq is small,MTPAcontrol is still accurateusing tint. Inaddition,
because Lq ≥ Ld, the inertia of iq is higher and the change rate of iq is smaller if appliedwith the
samevoltage,whichmakes thecalculated integrationtime tint isbiggerandthethresholdof torque
saturation ishigher.
Whenusing id= 0control, due to the currentof axisdbeing0, voltageequationsand torque
expressionofmotor indqcoordinationhavechangedto:
ud=−ωrLqiq (9)
uq=Rsiq+Lq diq
dt +ωrψf (10)
Te= p0ψf iq. (11)
Voltagevectorshave therelationship:
u2s=u 2
d+u 2
q=(−ωrLqiq)2+(Rsiq+Lq diq
dt +ωrψf) 2
. (12)
248
Emerging Technologies for Electric and Hybrid Vehicles
- Titel
- Emerging Technologies for Electric and Hybrid Vehicles
- Herausgeber
- MDPI
- Ort
- Basel
- Datum
- 2017
- Sprache
- englisch
- Lizenz
- CC BY-NC-ND 4.0
- ISBN
- 978-3-03897-191-7
- Abmessungen
- 17.0 x 24.4 cm
- Seiten
- 376
- Schlagwörter
- 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)
- Kategorie
- Technik