PROCEEDINGS OF THE INSTITUTE OF VEHICLES 4(95)/2013

Transcription

1 PROCEEDINGS OF THE INSTITUTE OF VEHICLES 4(95)/2013 Adrian Chmielewski 1, Kamil Lubikowski 2, Rober Gumiński 3, Sanisław Radkowski 4, Przemysław Szulim 5 MODELING OF THE PROPERTIES OF AUTOMOTIVE BATTERIES OF AN ELECTRICAL VEHICLE OPERATING IN NEDC CYCLE 1. Inroducion The aer resens he srucure and he roeries of elecrochemical auomoive baeries. Curren develomen rends in auomoive indusry oin o increased demand for hybrid ower ransmission sysems which are equied wih wo sources of energy: he rimary one (he combusion engine) and he secondary one, namely elecrochemical baeries (wih diverse hybridizaion degrees: Micro, Mild, Full Hybrid and Plug In Hybrid). The forecased develomen of HEV and EV drives, as foreseen by [1], is resened in figure 1. Fig. 1. The oulook for energy: A view o 2040 [1] 1 Adrian Chmielewski, MSc, Eng., PhD suden, Faculy of Auomoive and Consrucion Machinery Engineering, Warsaw Universiy of Technology 2 Rober Gumiński, Assis. Prof., PhD, Eng., Insiue of Vehicles. Warsaw Universiy of Technology 3 Przemysław Szulim, MSc, Eng., Assisan, Insiue of Vehicles, Warsaw Universiy of Technology, 4 Prof. PhD Eng. Sanisław Radkowski, Dean of Faculy of Auomoive and Consrucion Machinery Engineering, Warsaw Universiy of Technology 5 Kamil Lubikowski, MSc, Eng., PhD suden, Faculy of Auomoive and Consrucion Machinery Engineering, Warsaw Universiy of Technology 21

2 2. Modeling of an elecrical vehicle 2.1. Proeries of elecrical vehicles Growh of he degree of hybridizaion as well as a car s energy balance require use of baeries wih higher densiy of energy (he drives of HEV hybrid vehicles) as well high ower densiy (he drives of EV elecrical vehicles) figure 2 resens he ranges of energy and ower densiy for elecrochemical baeries as well as ulracaaciors [2]. Fig. 2. Regone lo of a few elecrochemical energy sorage devices used in he roulsion alicaion [2, 3] In rincile a hybrid drive consiss of a rimary and secondary source of ower. A combusion engine is he original source of ower. I is characerized by irreversible work. The secondary source of ower is in urn characerized by reversible work. In he case of an elecrical moor here is only he secondary source of ower, namely he elecrochemical baeries. The diagram of an elecrical drive, based on [4], is resened in figure 2. I consiss of elecrochemical baeries, an elecrical moor (when a vehicle moves a a consan seed or acceleraes, i works as a moor, while during deceleraion (braking), i works as a generaor which charges he elecrochemical baeries), and a differenial mechanism which drives he wheels. Fig. 3. Primary elecric vehicle owerrain [4] Elecrochemical baeries mus be equied wih Daa Baery Managemen Sysems (DBMS) which conrol he degree of charge/discharge so ha he driver is aware how much disance he can sill cover. The mos imoran feaures of DBMS include: Sae of Charge/Discharge monioring, i.e. he level of baery charge, monioring of a cell s emeraure gradien during charging and discharging as well as monioring he ambien 22

3 emeraure in which a cell oeraes. The yical DBMS conrol sraegies, according o [5], are resened in figure 3. They are mos ofen execued as Sae Machine. Fig. 4. Energy managemen conrol sraegies for HEV and EV [5] 2.2. Mahemaical relaions used for develoing he simulaion model. Based on [6, 7, 8] he momen of resisance of a vehicle s moion can be resened in he following form: m vehicle mass [kg], 2 M ( m gf 0.047Ac V m a) r (1) g acceleraion of graviy [m/s 2 ] f rolling resisance coefficien according o Dębicki and Arczyński [7, 8], defined by he following relaionshi: x w 2 f f0(1 AV ) (2) f basic rolling resisance coefficien (for ashal according o [6, 7] f ) 0 0 A end face area [m 2 ] c air fricion coefficien, x V vehicle velociy [m/s or km/h], roaing mass coefficien, amouning [6, 7]: w J momen of ineria of an elecrical moor s roor, s k 2 4 j1 1 w 1 J s 2 m J (3) k 2 r mr d J momen of ineria of he wheels ransferred o he elecrical moor s shaf, j oal ransmission raio beween he driving moor s shaf and he wheels, 1 efficiency of ower ransmission. m The ower of moion resisance will be: 1 d d 23

4 V N M (4) r Based on [8] he equaion which describes he volage a he elecrical moor s clams has he following form: u z d di Ri L e (5) d R resisance of saor wiring, i saor curren, L inducance, e k e elecromoive force ( k e elecrical consan, roor s angular velociy) The elecrical moor s orque according o [8, 9] is: M s M b M M l (6) M orque deenden on angular acceleraion and he roor s ineria, b M l 0 orque of losses in bearings. To reflec he auomoive roeries of an elecrochemical baery, one needs basic informaion regarding changes of he elecromoive force, usable and nominal volage and caaciy of he elecrochemical baery. For a single cell, he change of he elecromoive force [8, 9] can be described by he following relaion: E SOC (7) SOC usable caaciy of he baery, defined by he following relaion [8, 9]: Q SOC Q Q usable caaciy of he baery, defined by he following relaion [8, 9]: s i baery curren, a Q nominal caaciy of he baery, n s n ( ) Qs c ( ) a ( ia,, ) Qn ia ( ) d (8) 0 24

5 c ( ) emeraure based indicaor of he nominal caaciy c ( ) =1 for nominal oeraing condiions for a baery. When he baeries oeraing condiions are differen from he nominal condiions, he indicaor is deermined on he basis of he equaions found in [8]. sored usable energy coefficien a a i a( ) / I, n 1.3 a consan deermined on he basis of he Pekuer equaion, according o [8]. If ia( ) I n a 1. The change of he volage on he baery s clams [8, 9] can be described by he following equaion: R inernal resisance for a single cell w U (, k) E( k) i ( ) (9) a R w 2.3. Simulaion model of an elecrical car Malab Simulink The simulaion model of an elecrical vehicle s ower ransmission sysem consiss, in rincile, of: he inu block, which defines he NEDC cycle, he vehicle s resisance o moion (air drag, rolling fricion, ineria and sloes of he road [6, 7], if any, as well as he secondary source of ower, namely he elecrochemical baery. Figure 5 resens a diagram of he simulaion model of an elecrical vehicle creaed in Malab Simulink rogram. Fig. 5. Elecric vehicle Simulink model Table 1 resens he deails of he elecrochemical baery while ables 2 and 3 conain he inu daa for he elecrical moor and he elecrical vehicle. Table 1. Deails of he elecrochemical baery Cell volage [V] 2,12 (for k = 1) Caaciy [Ah] 120 Number of cell

6 Table 2. Deails of he elecric moor Nominal curren [A]: 120 Saor resisance [Ω] 0,1 Saor inducance [mh] 5 Elecrical coefficien [Vs/rad] 0,238 Mechanical coefficien [Nm/A] 0,238 Nominal Torque [Nm] 64 Nominal roaional seed [rm] 3600 Maximal roaional seed [rm] 5200 Momen of roor ineria [kgm 2 ] 0,03 Table 3. Deails of he elecric car Vehicle mass [kg]: 850 Fron surface square [m 2 ]: 2,08 Aerodynamic resisance coefficien (c x ) 0,36 Wheel radius [m] 0,26 Torque of ineria of vehicle wheels 0,46 Power ransmission 0,97 Figure 6 shows he NEDC cycle which is loaded ino Malab worksace. Fig. 6. NEDC cycle (New Euroean Driving Cycle) 26

7 Fig. 7. The changes of volage a he baery s clams Figure 7 resens he changes of volage a he baery s clams as obained from he model in which he vehicle moves according o he NEDC cycle. The vehicle s demand for ower increases raidly during he acceleraion hase. The elecrochemical baery becomes discharged raidly and as a resul he volage a he baery s clams decreases. During a consan movemen (no acceleraion), he volage a he clams decreases in a uniform manner here is no raid ower consumion in he sysem. When he vehicle is braking and recovering energy, he flow of ower in he ower ransmission sysem is reversed i is he force of ineria ha drives he vehicle. The elecrochemical baery is charged (he elecrical moor works as a generaor). As a resul, he volage a he baery clams increases. Fig. 8. Elecromoive force on he elecrochemical baery during NEDC cycle 27

8 Fig. 9. Change of SOC (Sae of charge) of he baery Figure 8 resens he working of he elecromoive force on he elecrochemical baery s clams. Change of he elecromoive force deends on he sae of charge (Figure 9) and hence boh runs are similar. During he acceleraion hase he elecromoive force and SOC decrease inensively (inensive discharge high consumion of ower from he cell figure 10). During a consan moion hase, here occurs a sraigh line decrease of SEM (Figure 8) and of SOC (figure 9) of he cell) he value of he discharged curren inensiy is osiive. During braking wih energy recovery, SEM and SOC values increase, however due change of he direcion of ower flow, he curren has negaive value (figure 10). Fig. 10. Changes of he baery s charge/discharge curren. 28

9 Conclusions The aer resens a model of an elecrical car which allows deerminaion of volage change, elecromoive force, degree of charging and he value of he simulaed curren for an elecrical vehicle moving according NEDC cycle [10]. As he discharge curren increases, he volage a he baery clams decreases and so do he elecromoive force and SOC. In addiion, in he final sage of he cycle one should noe he high charging curren (which significanly exceeds 3C) ha he baery is unable o absorb effecively in full [11]. To be able o effecively sore he energy in a cell, i is necessary o selec he relevan conrols (Daa Baery Managemen Sysem [5]. Acknowledgemen This work is he resul of he ineres and knowledge ha has been gained during he lecures iled: hybrid elecro mechanical basis led by Professor Anoni Szumanowski on he Faculy of Auomoive and Consrucion Machinery Engineering (SiMR). References: [1] ExonMobil Reor h:// akualizacja [2] Moni F.,,Hybrid and elecric vehicles. Powerrain archiecure and sizing design.'', Poliecnico Di Torino [3] Pisoia G.,,Baery oeraed and sysems: from orable elecronics o indusral roducs'', Elsevier, Amserdam [4] Teke A.,, A comrehensive overview of hybrid elecric vehicle: Powerrain configuraions, owerrain conrol echniques and elecronic conrol unis'', Elsevier, Energy Conversion and Managemen, Vol. 52, Issue 2, February 2011, Pag: [5] Young K.,, Elecric Vehicle Baery Technologies'', Ovonic Baery Comany, Rocheser Hills, MI, USA [6] Dębicki M.,, Theory of a car, drive heory'', WNT, Warsaw [7] Arczyński S.,, Theory of vehicle moion'', Wyd. PW, Warszawa [8] Szumanowski A.,,Energy sorage in vehicles'',wkił, Warsaw [9] Szumanowski A., Yuhua C., :,, Baery Managemen Sysem Based on Baery Nonlinear Dynamics Modeling'', IEEE, Vehicular Technology,Vol.57, Issue 3, Pag , Warsaw Universiy of Technology. [10] Żółowski A.,, Pomiar w warunkach nieusalonych'', Journal of KONES Inernal Combusion Engines 2003, vol. 10, : [11] Czerwiński A.,, Akumulaory, baerie, ogniwa'', WKiŁ, Warszawa Summary The aer resens a simulaion model of an elecric vehicle which racion roeries were showing in NEDC cycle. Basic relaionshi beween he curren charge / discharge of baery, baery volage a he erminals and he change of SEM as well as charge level elecrochemical baery was considered. Nominal condiions of he baery were assumed. For condiions oher han nominal baery emeraure coeffcien should be adjused. The model allows he simulaion of he elecric vehicle baery a differen emeraures. Keywords: Elecric vehicle, Baery, NEDC cycle. 29

10 MODELOWANIE WŁASNOŚCI BATERII TRAKCYJNYCH POJAZDU ELEKTRYCZNEGO W CYKLU NEDC Sreszczenie W racy rzedsawiony zosał model symulacyjny ojazdu elekrycznego, kórego własności rakcyjne odniesiono do cyklu NEDC. Zobrazowano odsawowe zależności między rądem ładowania/wyładowania baerii, naięciem na zaciskach, zmianą SEM oraz sonia naładowania. Przyjęo warunki nominalne racy baerii. Dla innych od nominalnych warunków racy baerii należy odowiednio skorygować emeraurowy wskaźnik ojemności nominalnej wyznaczając go z układu równań. Przedsawiony model ojazdu elekrycznego umożliwia symulację racy baerii w różnych emeraurach. Słowa kluczowe: Pojazd elekryczny, akumulaor elekrochemiczny, cykl NEDC 30