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Energies 2017,10, 616
Forpractical application,wedeïŹnean integration threshold sensitivity coefïŹcient so that the
actual integrationthreshold is:
Ith= kIIlim= 1
2 kITemaxtint= 1
2 kIp0Ïf ismaxtint. (19)
InEquation (19),Temax is themaximumelectromagnetic torque in the currentwindingmode.
For integration threshold sensitivity coefïŹcient kI â (0,1), the bigger kI is, the bigger integration
threshold Ith isandthelesssensitivethejudgmentoftorquesaturation,whichcanreducethepossibility
of improper switchingbutwill also increasedelays inwindingmode switching; the smaller kI is,
the smaller integration threshold Ith is and themore sensitive the judgment of torque saturation,
whichcanmaketorqueswitchingswiftbutmayleadto improperswitchingwhenworkingconditions
changeunexpectedly. By changing ks and kI,we canmodulate the sensitivity and stability of the
torquesaturation judgmentalalgorithm.
It is important to note that if the currentmode is trianglemode, upswitchingâs goal is only
independentmode;whenthe torquesaturationthreshold is reached, thecurrentmodeisswitchedto
independentmode.However, if thecurrentmode is starmode, thereare twooptions: triangleand
independentmode;when the torquesaturation threshold is reached, terminals aredecidedby the
degreeofsaturationofstatorcurrentvector.Whentheamplitudeofstatorcurrentvector isâ„ ismaxÎ,
it indicates that theamplitudeof thestatorcurrentvector in thecurrentmodeexceeds thecapacityof
adjustmentof trianglemodeandupswitchingâsgoal is independentmode;when is< ismaxÎ, thegoal
is trianglemode.
Downswitching is determined by the rotary speed threshold, which is the base speed of
eachwindingmode.When themotorâs rotary speeddecreases to the star or trianglemodeâs base
speed,downswitching is triggered. This strategy staggers theworkingpointsofupswitchingand
downswitching to avoid frequent switching. Switching is not onlydecidedby themotorâs speed,
likeupswitching,butalsobythedegreeof saturationof thestatorcurrentvector.Whether thecurrent
mode is triangle or independent, as long as themotorâs speedhas the relationship nr < nbY the
motorâs speed is lower than the starmodeâs base speed, and the currentmode is switched to star
mode. However, if the currentmode is independent and themotorâs speed has the relationship
nbY<nr<nbÎ, ithas tobedecidedwhether toswitch to trianglemodeornot.Whentheamplitude
ofstatorcurrentvector isâ„ ismaxÎ, this indicates that theamplitudeof thestatorcurrentvectorhas
exceededthecapacityofadjustmentof trianglemodeandcurrentwindingshouldstay in independent
mode. If is< ismaxÎ, thecurrentmode isswitchedto trianglemode.
Switchingprinciplesamongthe threewindingmodesaresummarized inTable2.
Table2.Switchingalgorithmofeachwindingmode.
StartingMode
SwitchingGoal Star
Mode TriangleMode IndependentMode
Starmode NA Positive
torquesaturationdecisionand
is< ismaxÎ Positive torquesaturationdecision
and isâ„ ismaxÎ
Trianglemode nr<nbY NA Positive torquesaturationdecision
Independentmode nr<nbY nbYâ€nr<nbÎ and is< ismaxÎ NA
3.Dual InvertersâCurrentModulationMethod
Thispaperadoptsahysteresiscontrol-basedcurrentcontrolmethod. Insingle-sourcedstarand
trianglemodes, inverterscouldonlyprovidetwopotentials foreachwinding. Thus, the traditional
hysteresiscurrentcontrolmethodwasadopted. Indual-sourcedindependentmode,dual inverters,
whencontrolledcoordinately, couldprovidethreeor fourpotentials.Hence,amulti-levelhysteresis
currentcontrolmethodwasemployed.
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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