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Energies 2016,9, 563
Table2.Comparisonbetweenthebatterymodels.
Feature BatteryModel1 BatteryModel2 BatteryModel3
Charge-Discharge
hysteresis ++ Considered in the
outputvoltage + Considered in the internal
resistance (R) equations - Charge-discharge
Opencircuitvoltage - Constantvalue forE0 + VOC(SOC) + VOC(SOC)
Internal resistance (R) - Constantvalue ++ R(SOC,T,C-rate) + R(SOC,T)
Temperature
influence - Notconsidered + Considered in the internal
resistancemodel + Consideredaspotential
correctionterms
Capacity fading - Notconsidered + Considered in
thebattery’susedcapacityestimation + Considered in the
battery’s internal
resistance (R) estimation
TotalAssessment 2 6 4
4.BatteryThermalModel
Ageneralenergybalance isappliedtoestimate thebatterycell temperature. It isassumedthat
the thermaldistribution inside thecell isuniformandthat theconductionresistance inside thebattery
cell isnegligiblecomparedwith theconvectionandradiationheat transfer [1,23,27,28]. Thechange in
temperaturedependssignificantlyonthebattery thermalcapacity (Cp) andthedifferencebetween
thegeneratedheat and thedissipatedheat. Thedissipationof theheat to thebattery surrounding
isperformedbyconvectionandradiation.Generatedheatcomprises twosources, irreversibleheat
generationbymeansof theeffectiveohmicresistanceof thecell’smaterial, andreversiblegenerated
heatdueto theentropychange inbothcathodeandanode. Thetotalentropychanges in thebattery
cell canbeconsideredaszeroaccordingtoReferences [1,29,30]. The temperaturedevelopment inside
thebatterycell isdescribedas:
mCp dTcell
dt “ ipVOC´Vbattq´hAcellΔT´ σAcell ´
T4cell´T4amp ¯
(7a)
whereΔT is thedifferencebetweenthebatterycellandtheambienttemperatures(Tcell´Tamp),h is the
natural convectioncoefficient,m is the cellmass, i is the cell current,Acell is the surfaceareaof the
singlebatterycell,σ isStefan-Boltzmannconstant,andε is theemissivityofheat.Assumingthat the
temperaturedifferencesbetweenthecells in thesinglebatterymodulearesmall,Equation(7a)canbe
generalizedfor thewholebatterymoduleas:
MCp dTcell
dt “ IpVOC´Vbattq´hAΔT´ σA ´
T4cell´T4amp ¯
(7b)
whereM is the total cellsmass, I is thebatterycurrent,A is thesurfaceareaof thecellsblocks in the
singlebatterymodule.
Sawet al. [23]haspointedout to the contributionof the contact resistance inheatgeneration.
Thecontact resistancecanbeneglected inthe investigatedbatteries, since thecellsarerealizing low
ohmicoverwidecell connectorsbymeansofweldedconnections. Fifty individualcellsareconnected
inparallel andwehaveanominal currentabout1.4Apercell. The resistanceof thesingle contact
is0.2mΩ.Withfourweldingpointspercell connectors, thecontact resistance for thesinglebattery
cell became 50μΩ. The power loss in the single cell due to contact resistance is determined as:
Ploss = Icell2Rcontact =0.098mW/cell,which isanegligibleamount, thermally,aswellaselectrically.
5. ExperimentalCharacterizationof theBatteryandtheVehicleunder theTest
5.1. BatteryMeasurements
Inorder tocharacterize theLiFeMgPO4-battery, severalexperimental testswere implementedon
thebatteryatdifferentconditions.OCVvs. SOCmeasurementswereperformedat10,20and40˝C.
Thebatterywasdischargeduntil thecut-offvoltageof2Vwasreachedandthenrechargedupto the
nominal capacity. ALowC-rateofC/10wasused tominimize thedynamiceffectsand toachieve
agoodapproximationtoanopencircuit. Figure5demonstrates thechargeanddischargeOCVcurves
131
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