Page - 138 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2016,9, 563 19 number of Modules U exp Sim e% Subsystem Saturation PE f(u) OCV(SOC,T)_dis2 Lowpass Lowpass Filter SOC T[°C] I_Crate I_cell U_R R Lam, Bauer RC Model 1/s Integrator -K- Gain4 K Ts z z-1 Discrete-Time Integrator2 E0-R*i Q(Capacitance) it i* i E_batt Discharge-Charge dynamics 1/50 Cells current 6 Cell Blocks -K- C-Rate Calculation V_cell VOC i_cell Ambient Temp Tbatt0 Battery Temperature Battery Temperature Model |u| |u| Abs 5 T_Cell 4 T_ambient 3 SOC0 2 Actual battery pack voltage 1 Measured battery pack current Figure13.Theproposedsynthesizedbatterysimulationmodel. 7.Conclusions A battery is a sophisticated system, which necessitates a detailed model for accurate simulation. Many factorsmustbe considered in thebatterymodel for accurate simulation results. Charging-dischargingdynamics, battery internal resistance, andopencircuit voltageare themost significantaspects forbatterymodeling. Temperature isan influential factor forallof theseaspects. Thedifferencebetweenthecharginganddischarging in theOCVcurves increasesat lowtemperatures. Thisphenomenonoccursdueto thedecrement inbatterycapacity,which in turnappearsasaresult of a rise of the internal resistance. Neglecting the effect of temperaturewill lead to inaccuracy in simulation. Eventheslightesterrors in thesimulationresultsof thebatterycellmodel,wouldgrow significantlywhenthemodel isextendedto thecompletebatterypack. Batterymodel1has twoflaws. Firstly, it assumes the initialvoltagevalue tobe thenominalbatterycellvoltage. Thisassumption led to largeoffset fromtheactualvalue,whenthevehiclewas testedatabout30˝C.Secondly, it considers aconstant internal resistanceof thebattery,which is in factaveryfluctuatingquantity thataffects the batterycell currentandthevoltageresponseaswell. Theproposedbatterymodelhascompensatedfor theseshortagesandithasaccuratelysimulatedthebatterypackvoltageresponseontherealvehicle. AuthorContributions:MuhammedAlhanoutimadetheliteraturereviewonthecurrentbatterymodels,proposed the synthesizedbatterymodel, developing the simulationmodels, andwrote thepaper. MartinGießler and ThomasBlankdesignedandperformedthebatterymeasurements,andtheyhelpedinediting thepapercontent. FrankGauterinsupervisedtheworkof thispaperandapprovedtheresults Conflictsof Interest:Theauthorsdeclarenoconflictof interest. AppendixA AppendixA.1.Nomenclature TableA1.Batterymodelsparameters. Parameter (Unit) Symbol Value Constantvoltage (V) E0 3.21 [23] Constant internal resistance (Ω) R 0.0833 Polarizationconstant (V/(Ah))orpolarizationresistance (Ω) K 0.0119 [23] Batterycapacity (Ah) Q Variable 138