Mobility in modern metropolitan cities is plagued by overcrowding, producing. Prototype by ENEA for Urban Mobility. Ennio Rossi and Carlo Villante

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1 LUSHPIX Prototyp by ENEA for Urban Mobility Ennio Rossi and Carlo Villant Mobility in modrn mtropolitan citis is plagud by ovrcrowding, producing congstion, low transit spd, ful consumption, air pollution, and parking problms. On of th causs of ths phnomna is th growing markt of vhicls of xcssiv siz with rspct to thir mor frqunt us. Th tchnological and commrcial dvlopmnt of vhicls spcifically concivd for urban us, and thrfor limitd in siz, not xubrant in prformanc, and with low ful consumption and missions would crtainly b mor dsirabl. Hybrid driv trains ar particularly suitd to this purpos: proprly dsignd, minimal thrmal ngins can fit th Digital Objct Idntifir.9/MVT..98 Dat of publication: Novmbr -//$. IEEE IEEE VEHICULAR TECHNOLOGYMAGAZINE DECEMBER

2 application, giving an lctrical driving option whn rquird. Th prototyp shown in this articl has bn spcifically concivd to b a city car with a so-calld sris hybrid traction architctur bing a living xampl. By combining appropriat and availabl tchnologis, modrn componnts, and carful planning, it is possibl to achiv rsults usful for th usr and for th community. Urb- is a prototyp of city vhicls mploying a sris hybrid driv architctur. Th nam coms from th contraction of th two English words, urban and asy, and dfins th natur and vocation of th car. Th motivation of prototyp is twofold: on on hand is th dmand for spcializd ngins for citis with a high dmand of mobility and thrfor with traffic problms (Rom was our focus); on th othr hand is th tchnological maturity of hybrid driv systms. It is about a dcad, in fact, that mtropolitan aras witnss birth (and affirmation) of individual transport mans, which ar ssntially inadquat to mt thir mobility rquirmnts. First, two-whld vhicls wr bing sold for amusmnt purpos and/or short-rang mobility but bcam, for most of th mtropolitan inhabitants, th only way to gt around th city and b abl to park, vn during th wintr and in th rain. Scootrs, in fact, ar a way to cop with mobility dmand, but thy incras passngrs discomfort and th numbr accidnts. Scond, in som Europan citis, so-calld quadricycls ar minimal-sizd vhicls, which originatd in Franc to solv th rural nds and to assist agd drivrs and othr popl who had lost thir driving licns. In Italy, thir diffusion was ssntially confind in th main citis, lading to an actual flt of approximatly 8, units. Car markt shar is currntly around.%. So quadricycls in Italy bcam, dspit thir high pric (about,) and poor tchnical quality, a status symbol for tnagrs and a possibl transport mans to accss limitd traffic zons. Major car manufacturrs, with th xcption of th Mrcds group (with its Smart brand), ar now focusing on th potntiality of this markt sctor and ar launching nouvll two-sat products (Fiat and Toyota). Within this fram, th Italian Enrgy and Environmntal Agncy (ENEA) proposd th Urb- prototyp, whos main aim is showing th applicability of hybrid propulsion tchnologis vn in a limitd vhicl architctur, lading to a low nvironmntal impact vhicl and also having a purly lctric driving mod (Figur ). Our main dsign spcifications wr th following: n footprint lss than m in lngth n wight of kg n low ful consumption, possibly clos to th targt of L pr km n missions comparabl with Euro passngr car dirctiv (which ar not compulsiv for this vhicl catgory) n possibility of driving in lctric mod for about km n no garbox or clutch n accptabl driving prformanc: maximum spd of km/h, good acclration, and ability to ovrcom ramps of % n as of production and industrialization of th vhicl through th utilization of commrcial componnts n xtrior aspct that raiss curiosity among th nonprofssional public. To ths aims, our first dsign choics rgardd th following vhicl architctur: n tubular wldd iron chassis, giving rquird robustnss and as of ralization n lctrical storag in ultracapacitors (UCs) instad of battris, bcaus of thir highr prformanc and longr lif n synchronous brushlss prmannt magnt lctrical machins, bcaus of thir high prformanc and controllability n working voltag btwn and V as a compromis btwn nrgy losss and availability of commrcial componnts n primary small displacmnt thrmal ngin fd by gasolin, normally usd for scootr propulsion. Th projct was dvlopd in collaboration with Rom La Sapinza Univrsity and with Roma Univrsity, focusing mainly on purly mchanical topics and thn on th ralization of lctric convrtrs for th managmnt of lctrical machins and UCs. Almost all assmbly, tuning, and tsting work wr conductd at th ENEA Casaccia Rsarch Cntr, making us of facilitis and tsting apparatus of th Low Impact Vhicls Lab. Calibration tsts wr dvlopd on a dynamomtr rollr bnch and road tsts wr don in Casaccia running across an intrnal road ntwork. A small circuit was also ralizd in th occurrnc of Associazion Tcnica dll Automobil (ATA) 9 Formula Elctric and Hybrid Italy, an vnt and rac hld in Casaccia (at which Urb- took part). DECEMBER IEEE VEHICULAR TECHNOLOGY MAGAZINE

3 FIGURE Th Urb- xposd at a 8 motor show in Bologna. Vhicl Dscription Th rolling chassis consists of wldd stl tubs with an xtrnal diamtr of mm, thicknss of mm, for th main structur and -mm tubs for stiffning triangls (Figur ). Th ovrall vhicl dimnsions ar. m lngth and. m width. Both front and rar suspnsions wr mad by a dformabl paralllogram composd of highr and lowr swinging triangls, coil springs, and coaxial damprs. Th FIGURE Th rolling chassis. chassis has bn partitiond with aluminum alloy shts: on th bottom of th car and in vrtical (bhind th passngr s sats) to crat a sparation and a protction from th rar ngin. Finally, two strong stl plats wr placd horizontally to adjust th mchanical parts. A sris hybrid architctur was chosn, consisting of n a motor-gnrator group [gnrator unit (GU)], composd of a primary combustion ngin [intrnal combustion ngin (ICE)] and an lctrical gnrator (EG) mutually connctd through a constant ratio blt driv n an nrgy storag systm basd on UCs n an lctric driv acting on front whls [traction motor (TM)] n an lctric nod prmitting mutual nrgy fluxs (rfrrd as link in th following) n thr lctrical convrtrs n a powr managmnt systm dfining th nrgy fluxs (Figur ). As a primary thrmal ngin, a Piaggio QUASAR cm, which quips Vspa GTV and GTS modls as wll as Bvrly, MP, and X, was chosn (Figur ). It is a modrn ngin with four valvs and lctronic injction, approvd for motorcycls according to Euro standards, whos main tchnical data ar givn in Tabl. Th EG (Figur ) is a brushlss prmannt magnt machin producd by ACM basd on our tchnical rquirmnts. Th main faturs of th EG ar shown in Tabl. Th EG is drivn by ICE. To coupl th machins, a blt pully transmission was chosn with a constant transmission ratio (Figur ). Th : ratio was calculatd to optimiz th fficincy of th motor-gnrator group. Also, th lctric TM (Figur ) has bn built on our spcifications by ACM with th sam construction tchnology. Th main faturs of TM ar givn in Tabl. Th lctric motor is rigidly assmbld with a diffrntial gar with a final rduction qual to.:. Th UCs wr chosn among thos sold by Maxwll Tchnologis: four moduls at V and F wr usd, connctd in sris (Tabl ). Each modul, vn if mad by six lmntary capacitors, is rigidly assmbld and UC Storag Systm TM with Transmission ICE EG Hybrid Managmnt CPU FIGURE Th traction systm layout. FIGURE Th adoptd ngin. IEEE VEHICULAR TECHNOLOGYMAGAZINE DECEMBER

4 TABLE Intrnal combustion ngin. TABLE Elctric gnrator. Typ Singl Cylindr, Four Strok Typ Synchronous Prmannt Magnts Displacmnt. cm Bor mm Strok mm Cooling Liquid Timing Four valvs, singl cam Maximum powr. kw at 8, r/min Maximum torqu. N.m at, r/min Injction Elctronic Wight kg Emissions Euro Catalytic Thr ways Voltag rms V Ratd powr kw Pak powr 8 kw Ratd torqu N m Rotational spd, r/min No. of pol pairs Magnts NdFB Cooling Liquid Wight kg boxd in an aluminum housing. An imag of th whol systm is prsntd in Figur 8. Each on of th thr lctrical componnts (altrnator, ngin, and UCs) is compltd by a convrsion group consisting of MOSFET diods lmnt and an lctronic control basd on a digital signal procssor (DSP). Th groups ar ssntially th sam but us diffrnt programs to fulfill diffrnt tasks. Th control lctronics and th diod componnt (mad by Smikron) ar shown in Figurs 9 and. To cool th diffrnt parts, two sparat cooling circuits wr rquird. Th first on, with watr at about 9 C, is th original quipmnt of ICE and uss th circulation pump intgratd to th ngin, th tmpratur control valv, and a radiator with an lctric fan biggr than th original on, which was dsignd for motorcycl applications. Th scond circuit, with watr at C, cools lctrical machins and convrtrs. It uss an lctric pump and a radiator with a fan that is always turnd on. Th lctrical architctur of th systm was dsignd to mt svral rquirmnts: FIGURE Housing of th GU on th back of th vhicl. n ability to driv th altrnator both in currnt and in spd n capability for UCs to work with larg-voltag xcursions FIGURE Th lctric gnrator. FIGURE Th lctric TM. DECEMBER IEEE VEHICULAR TECHNOLOGY MAGAZINE

5 TABLE Th Elctric TM. Typ Synchronous with Prmannt Magnts Voltag rms V Ratd powr 8 kw Pak powr kw along min Ratd torqu N.m Maximum torqu 8 N.m Rotational spd, r/min No. of pol pairs Magnts NdFB Cooling Liquid Wight kg FIGURE 9 Th lctronics of convrtrs. TABLE Ultracapacitors. Faturs of a Singl Modul Producr Maxwll Modl BMOD E Nominal voltag. V (six clls by. V) Capacitanc F Spctral nrgy. Wh/kg Spctral powr. kw/kg Whol Systm (Four Moduls in Sris) Nominal voltag.8 V Capacitanc F Enrgy Wh Powr kw Siz 8.8 L Wight kg n cration of a stabl voltag at nod of convrgnc of lctrical systms (link) n possibility of torqu control of TM. In addition, thr ar obvious quipmnts for normal cruising such as rvrs driving, nrgy braking rcovry, and pur lctric driving. A high-lvl controllr was introducd, which is a programmabl logical unit Promthus. It is a logical multifunctional componnt producd by Diamond Systms Corporation and includs th following. n Promthus PC/ Modul: Th control unit for industrial procsss, scintific instrumnts, xprimntal apparatus, and data acquisition. It includs a procssor, Ethrnt ntwork connction, and quipmnts for input and output analogical data. It has a flash mmory of MB; th first kb of it nds to allocat th BIOS, whil th rmaining can b usd as an xtrnal mmory, suitabl to accpt th xcutabl program. n Ruby MM- Modul: A D/A signal convrtr for procss control with singl-ndd outputs. n Jupitr MM SIO Powr Supply Board: Provids four lvls of stabilizd voltags for powring all moduls, taking fd from -V srvic battry. n Controllr Ara Ntwork (CAN) AC- Communication Card: Th controllr bcoms a nod for CAN data xchang, allowing th suprvisory program to rad all th data and snd control signals to th componnts. Th communication among componnts and with th control unit is implmntd by a local ntwork that uss th. A CAN protocol at a spd of Mb/s. Th control systm of th ntir propulsion systm is dsignd as a distributd logic systm with a suprvision program. It consists of four main subsystms that communicat through CAN. Th subsystms ar th GU, UC, TM, and Promthus groups. Figur illustrats th connctions btwn th groups. Th four information words that ach logical group maks availabl to CAN (Figur ) ar FIGURE 8 Th front axl of a vhicl with TM and UCs. FIGURE Th diods of a convrtr. 8 IEEE VEHICULAR TECHNOLOGYMAGAZINE DECEMBER

6 n From th GU Group: rotational spd, dlivrd currnt, fr, and rrors n From th UC Group: UC and link voltag, link currnt, fr, and various mssags (ok, protction, and rrors) n From th TM Group: rotational spd, throttl position, brak position, and rvrs driv, protction, and rrors n From Promthus: st-point GU and TM currnts, fr, various mssags of nabling, and rrors from DSP. An analogu output (outsid CAN) is usd to control th ICE throttl, a digital output for th motion of a rlay, which givs th consnsus for ngin start and stop, and a digital input for th pilot to actuat th protction stop of DSP. Ths thr signals ar managd by Promthus (Figur ). Th managmnt of a thrmal ngin consists of a torqu control mad by tuning th currnt supplid by th altrnator and a closd-loop spd control actuatd by th throttl of ICE. Accordingly, its lvrag was motorizd through a systm consisting of a controllr, an lctronically controlld actuator. Th managmnt of th hybrid propulsion systm is ralizd by th suprvision program installd on th Promthus procssor unit that rcivs data from all snsors, actuators, and dvics fittd on th car. Th unit has basically th following tasks: n to manag th gnrator group, dtrmining, for a givn rquird mission, th powr that th GU has to produc n to manag th lvl of stat of charg (SOC) of th UCs and filtring impulsiv powr rqusts to hav a sufficint nrgy rsrv to covr dmand paks, whil maintaining a sufficint capacity to stor nrgy from rgnrativ braking n to idntify, for ach powr rqust for th GU, its bst oprativ conditions for ICE, basd on its fficincy maps n to prform th appropriat filtring of dynamic oprations, particularly rgarding th powr rqusts to TM and GU n to crat a virtual dashboard to viw main masurs, vntually prmitting som simpl manual actuations n to prform safty chcks to prvnt to xcd lctrical and mchanical limit valus GU ac/dc Convrtr DSP-Basd Controllr Promthus W h l W h l ICE Altrnator ac/dc Convrtr Link 8 V Invrtr dc/ac Elctric Motor Diffrntial Gar Tank Vac 8 Vdc FIGURE Th main componnts and nrgy flows. n. Words n. Words C A N TM B u s n. Words n. Words Diffrntial Gar FIGURE Th schm of an onboard CAN communication. dc/dc Convrtr DSP-Basd Controllr DSP-Basd Controllr dc/ac Invrtr UCs dc/dc Convrtr UC Vac Pdals W h l W h l DECEMBER IEEE VEHICULAR TECHNOLOGY MAGAZINE 9

7 n to prform data acquisition of all masurd paramtrs during th mission. For implmnting th control program, th Matlab Simulink nvironmnt was chosn (Figur ). Th softwar was thn compild and stord on th flash mmory of th Promthus dvic, which is basd on a ral-tim oprating systm. During vhicl opration, Promthus communicats with a host PC, which is installd onboard (a CarPC with a -in touch scrn was chosn), and implmnts th virtual dashboard functionalitis and acts as a data-storag dvic. In this way, Promthus runs th program in ral tim through CAN acquisition and I/O signals of its lctronic boards. Th managmnt softwar consists basically of two typs of blocks: blocks that manag and implmnt th functions of I/O and blocks that dfin th control logic. Th st of blocks by which th softwar is structurd is th following. n CAN Rad and CAN Writ Blocks and Ruby MM-: Ndd to manag th input and output functions n TM Block: Dals with th traction and UCs (Figur ) n GU and ICE Blocks: Involvd in th control of motor gnrator. TM block ruls out th dmands of throttl and brak by adopting th ncssary limitations. In particular, th block allows rgnrativ braking, which and is progrssiv with a givn law as a function of th position of th brak pdal, nabls lctric braking only if th spd xcds a thrshold and th throttl pdal is rlasd, and chcks whthr th currnt producd by th rcovry rmains blow its limit. Th block also controls th capability to absorb th charg from th capacitors and calculats th rquird rcharging powr. Th GU block manags th gnration group and, according to th limits imposd on gradints of capacitors charging and on altrnator currnt, assurs that th nrgy balanc in th link is satisfid. This way, it valuats th powr rqust for th GU group. Thn it chooss, basd on GU fficincy maps, th bst valus for its rquird oprativ point (rotational spd and torqu). Finally, th ICE block rcivs th valu of th st point on GU spd by th GU block and controls it, actuating throttl position within a closd loop by an intgral and proportional approach. Exprimntal Activity Th utilization of th ENEA dynamomtr has bn vry significant in achiving th goals of stability and prformanc optimization of th traction systm (Figur ). With this tool, it was possibl to monitor and thn chck in ral tim th volution of th main lctrical paramtrs and st th dsird running conditions. GU Mapping A prliminary activity was th obtainmnt of an fficincy map of th GU: tsts wr carrid out in diffrnt points of th ngin map. Th rsult of this first st of tsts is summarizd in Figur (a) (d) as four contour graphs, which ar th intrpolation of discrt fild data collctd (dnotd by th rd dots). It has bn possibl to dfin for ach dsird powr th corrsponding optimal rotational spd of th group (points indicatd by grn stars). This curv was imposd as an optimal rfrnc in trms of torqu and rotational spd for control softwar of th GU. In th graphs, n Figur (a) shows th hourly consumption of GU, ranging from g/h to,9 g/h (at kw,, r/min). n Th masurd spcific ful consumption of GU shows a minimum of g/kwh at kw and,8 r/min, whr th output nrgy in kilowatthours is masurd in ac out of th EG. CAN Rad TM Accl (%) Accl (%) Brak (%) Brak (%) SP i TM (A) i GU (A) i GU (A) w TM (rad_s) OK_TM V UC (V) OK_UC w TM (rad_s) OK TM V UC (V) SP P TM (W) OK UC OK_DSP OK_ICE w GU (rad_s) GU SP P TM (W) V UC (V) SP i GU (A) OK UC OK DSP SP w GU (rad/s) OK ICE CAN Writ SP i TM ds (A) SP i GU (A) SP w GU (rad/s) SP TPS (V) w GU (rad/s) ICE Stup CAN-AC- B CAN /CAN Standard/Extndd Ruby-MM- Diamond Analog Output Ruby-MM- FIGURE Th modl of th managmnt softwar. IEEE VEHICULAR TECHNOLOGYMAGAZINE DECEMBER

8 Acclrator (% at., at., % at ) i Max.9*u +.*u. Accl (%) / Min + + i Max (u 8)/* i GU (A) v UC (V) Brak on Spd > km/h OK Acc < w TM (rad/s) Rat Limitr OK TM SP i TM (A) -K- T/i TM SP P TM (W) FIGURE Th vhicl in tst on a rollr bnch. Rgn Brak (% at., % at., % at ) OK UC i Max +.9*u +.*u. / Brak (%) + i Engin FIGURE Th TM block. n Th spcific consumption of th vhicl, masurd at constant spd and with nding UCs voltag at th sam valu than starting on, has a minimum of nar g/kwh at kw and,8 r/min, whr th dlivrd nrgy is masurd in kilowatthours at th dc ntry of th TM. Thrfor, consumption dos not tak into account losss in th invrtr and TM itslf. n Basd on a masurd avrag lctrical consumption (in subsqunt dynamic tsts) on th Europan driving cycl (ECE) of Wh/km, it was possibl to stimat th consumption of th vhicl in kilomtr/ litr that would b achivd by making th GU work at a fixd point on th ECE. n AsshowninFigur(d),insuchaway,youcan gt a maximum targt of spcific rang for propulsion managmnt systm: just a littl mor than km/l on th ECE. It is obvious, as it will b shown latr, that th vhicl could achiv lowr consumptions if working on lss-xpnsiv conditions in trms of lctric powr consumption rquird by vhicl mission. Dynamic Prformanc Som tsts wr carrid out for prformanc vrification. Th main prformanc rsults ar summarizd in Tabl. Braking Charactristics Th brak is st on thr stags of opration. ) Rlas of th acclrator pdal: Th ngin brak is st to produc an lctrical currnt outgoing from TM by about A. This corrsponds to a constant braking torqu if th forward spd xcds km/h. This valu was chosn according to th plasur of driving xprinc that must rplicat as much as possibl th ffct of ngin braking of a convntional car with a combustion ngin. ) Brak pdal lowrd down until you finish th mchanical gaps only and without involving braking friction: A suitabl position snsor of pdal position informs th CAN about th prcntag of rgnrativ brak that you ar rquiring. This provids a DECEMBER IEEE VEHICULAR TECHNOLOGY MAGAZINE

9 8. Hourly Consumption g/h Stady Motor Gnrator Spcific Consumption g/kwh.. P (kw)..... (a) (b) 8. Stady Vhicl Spcific Consumption g/kwh ECE-Stady Point-Vhicl Consumption km/l.. P (kw) w (kr/min) (c) w (kr/min) (d).... FIGURE Spcific consumption of motor gnrator and slction of optimal oprating points. continuous modulation of th currnt rqust to th motor (which works as a gnrator) ranging from to A. This corrsponds to a braking capacity proportional to braking prcntag. TABLE Vhicl prformanc. Pur Elctric Rang Tsts (UCs Voltag Dropping from to 8 V) 8 m starting from still and driving at a stady spd of km/h m starting from still and driving at a stady spd of km/h m starting from still and driving at a stady spd of km/h m starting from still and driving at a stady spd of km/h m in acclrating tst starting from still and raching maximum spd of km/h Pur Elctric Maximum Acclration Tsts Constant acclration from to km/h: adds km/h in s, thn. m/s m in 9 s m in s m in s Maximum Spd Tst Maximum spd of 8 km/h, with a powr limitation on GU of 9 kw ) Brak pdal compltly and firmly downd: This adds to prvious action, th typical friction work of disc braks. This is th only possibl braking in stationary or in rvrs driving. Tsts on Urban Part of ECE Variabl spd tsts on th rollr tst bnch wr conductd following th urban part of th ECE, which is charactrizd by a top spd of km/h (Figurs and 8). In ths first tsts, GU is nvr stoppd during th mission. GU powr thrfor follows road rquirmnts, proprly filtrd to limit powr gradints for th GU whil maintaining a sufficint SOC for th capacitors. This mod will b hrinaftr rfrrd to as load following. This prliminary activity ld to th following considrations. n Rcordd tracs of lctrical and mchanical masurs show th prfct functionality of th UC. In fact, th GU group has a rducd dynamic, and impulsiv powr surplus (positiv and ngativ) is absorbd by UC. n It rsults that th oprating point of th GU is, for most of th mission, in aras with high ful consumption. n This is du to th prpondranc, in ECE, of phass of arrst and or at rducd powr. Th us of ICE, such as all Otto ngins, is pnalizd in low powr phass IEEE VEHICULAR TECHNOLOGYMAGAZINE DECEMBER

10 Powr (kw) ω GU (kr/min) Spd (km/h) (a) Rfrnc Actual (c) TM GU Tim (s) () V UC (V) i GU (A) (%) Acclrator Brak (b) Rfrnc Actual (d) Tim (s) (f) FIGURE Th urban part of ECE with load following control stratgy. by losss bcaus of air friction for th prsnc of th throttl at th inlt manifold. n Th control of th GU is quit fficint, both in trms of currnt (and torqu) and in trms of rotational spd. Th spd control was dlibratly kpt lss prcis than th currnt on, to avoid too intns transints to ICE (so obtaining a kind of filtring ffct) and also bcaus it was vrifid that th xcssiv prcision in spd control can ngativly intract with th prcision of currnt control. This could also produc (during havy load transints) possibl instability phnomna. Ths obsrvations mad it possibl to conciv a scond control stratgy for th GU, which compls it to work in th nighborhood of a powr of kw or to rmain off. This stratgy was calld ON OFF load following, sinc th GU group is ithr on or off, and whn it is on is controlld with th sam program stratgy than load following (Figurs 9 and ). P (kw) It is vidnt (compar Figurs 8 and ) that th shift of oprating points is in th lowst ful consumption zon. Th masurd rang passs from. km/l with th load following stratgy to 8. km/l with th ON OFF load following stratgy, with a dcras in consumption of %. Th tsts wr also rpatd limiting in slop th svrity of transints for powr on and powr off at W/s. ECE-Stady Point-Vhicl Consumption km/l w (kr/min) FIGURE 8 Th urban part of ECE with load following control stratgy: working points. DECEMBER IEEE VEHICULAR TECHNOLOGY MAGAZINE

11 (a) (b) igu (A) Rfrnc Actual (c) VUC (V) ωgu (kr/min) Powr (kw) Acclrator Brak (%) Spd (km/h) TM GU Tim (s) () Rfrnc Actual (d) Tim (s) (f) FIGURE 9 Th urban part of ECE with ON OFF load following control stratgy. turning th hat ngin in its bst oprating point just for th tim ncssary to produc th lctricity rquird by th mission of th vhicl. Howvr, this bst valu dos not tak into account th constraints imposd by limitd nrgy contnt of UCs, whos rcharg, as vidncd by th rsults, could rquir th dlivry by th GU group of a powr far gratr than optimal for maintaining th SOC sufficintly ECE Stady Point-Vhicl Consumption km/l distant from its minimum limit. Similar tsts wr conductd (with similar rsults, as discussd blow, in road tsts) trying to anchor th ignition and th stop of combustion ngin to th achivmnt of uppr and lowr limits for th voltag of th UC. Th control stratgy ON OFF load following was also tstd driving at a constant spd (a tst calld Marathon), providing a gratr accuracy and stability of th GU oprating point (Figurs and ) P (kw) Th ffct on consumption was indd light. Additional masurmnt campaigns ar mad to assss th ffcts of ths transints on th main vhicl xhaust missions. Th obtaind ful consumption is not far from th maximum targt of about km/l, which would b achivd by w (kr/min) Road Tsts FIGURE Th urban part of ECE with ON OFF load following control stratgy: working points. To confirm data obtaind on th dynamomtr rolling bnch, w IEEE VEHICULAR TECHNOLOGY MAGAZINE DECEMBER

12 Powr (kw) ω GU (kr/min) Spd (km/h) Acclrator Brak (a) (b) (c) (d) Rfrnc Actual TM GU Tim (s) Tim (s) () (f) (%) i GU (A) V UC (V) Rfrnc Actual FIGURE Th Marathon cycl with ON OFF control stratgy. carrid out a sris of road tsts mploying th intrnal strts at th ENEA Casaccia Rsarch Cntr. Th first ara w chos is rounding a football fild that consists of flat and lightly sloping strts, straight sctions, vry low-spd curvs, and stops. Th avrag road spd of th track is vry clos to 8 km/h. Kping a driving bhavior adquat to th road and th track, w achiv a condition vry similar to driving in th urban traffic. It is also comparabl with an ECE tst. Th lngth of th track is m and, in gnral, has bn run across svral tims for ach tst (Figur ). Th tsts wr using both control stratgis and substantially gtting confirmation of ful consumption data obtaind at th rolling bnch. As an xampl, w show som tracks of th tsts mad with load following stratgy that dmonstrat th agrmnt of th systm to xpctations, particularly th ability of UC to rplac th GU in highly dynamical phass, working with positiv and ngativ powrs up to kw. Th GU P (kw) group is thus allowd to work in a mor stabl way, with crtainly bnficial ffcts on xhaust missions and on its longvity. Also, tsts with ON OFF stratgy confirm th xpctations of low ful consumption. In ths tsts, too, th rsult of inducing th GU group to work in bttr aras has bn obtaind. Contact Spd Tst Cycl-Stady Point-Vhicl Consumption km/l w (kr/min) FIGURE Th Marathon cycl with ON OFF control stratgy: working points. DECEMBER IEEE VEHICULAR TECHNOLOGY MAGAZINE

13 FIGURE Th top viw of th track. Othr road tsts wr conductd on anothr circuit obtaind in a parking of Casaccia Cntr. Th charactristic of this scond track is to b almost prfctly oval, which also allows to prform tsts at a constant spd. A trial was conductd on this circuit to run at low spd and using ON OFF stratgy to rpat th good rsults obtaind on a dynamomtr rollr bnch. Unfortunatly, ithr bcaus of P (kw) Casaccia Cycl-Stady Point-Vhicl Consumption km/l w (kr/min) FIGURE Th Casaccia cycl with load following control stratgy: working points. changs of dirction wid ranging but always prsnt or bcaus of th prsnc of climbs and dscnts, th rsults wr blow xpctations (Figurs and ). Th latst road tsts wr prformd on th track in Casaccia, which is alrady usd for th comptition, ATA Formula Hybrid 9. Th circuit has prfct asphalt and svral straight sctions. Th avrag spd is mor than 8 km/h, and thus th consumptions ar slightly highr. Summary of Rsults in Trms of Ful Consumption In Tabl, th various tsts prformd and th masurd ful consumption ar prsntd. Comparisons W show, for compltnss of rporting, som trms of comparison of similar vhicls running on urban conditions: n Volkswagn Fox with gasolin ngin:. km/l n Nissan Micra with gasolin ngin:. km/l n Fiat Panda with gasolin ngin:.9 km/l n Mini with gasolin ngin:. km/l n Ford Ka with gasolin ngin:.9 km/l n Opl Agila with gasolin ngin:.9 km/l n Fiat with, disl ngin:. km/l n Smart with gasolin ngin: 8. km/l n Quadricycl AIXAM with disl ngin:. km/l. (Data for Fiat and AIXAM hav bn masurd in ENEA, whil othrs ar dclard by th manufacturr.) Consumption dclard by Piaggio for its scootr Bvrly, which mploys th sam ngin than Urb-, is km/l. Th scootr howvr has a mass of kg, whil Urb- wighs kg. Conclusions Th ralization program of th Urb- prototyp, vn though still improvabl on many aspcts, has rachd a stat of compltion, and th following conclusions ar drawn. n It was dmonstratd, through a running vhicl in complt safty and rliability, th fasibility of th hybrid sris traction vn in th fild of city cars. Th fild of application of this tchnology has in fact bn so far rstrictd to larg mass vhicls such as buss or trains. In automotiv applications, th only ons that hav so far found commrcial consnsus wr paralll hybrid cars. n Th possibility of using UCs in plac of battris has bn dmonstratd. Ths componnts, still not wll known and littl apprciatd, can offr significant IEEE VEHICULAR TECHNOLOGYMAGAZINE DECEMBER

14 P (kw) Casaccia Cycl-Stady Point-Vhicl Consumption km/l TABLE Rsults in trms of ful consumption. w (kr/min) FIGURE Th Casaccia cycl with ON OFF load following control stratgy: working points. Typ of Driving Prformd on Control Stratgy Rang (km/l) ECE Rollr bnch Load following. Fr driving Strt Load following. ECE Rollr bnch ON OFF load following 8. Fr driving Strt ON OFF load following. Constant spd:. km/h ATA track ON OFF load following. Constant spd: km/h Oval track ON OFF at fixd point.9 Constant spd: km/h Rollr bnch ON OFF at fixd point. Constant spd: km/h Rollr bnch ON OFF at fixd point. Constant spd: km/h Rollr bnch ON OFF at fixd point. bnfits for thir rliability and longvity whn compard with battris. n It has bn dmonstratd that th hybrid sris traction allows low ful consumption. Plas kp in mind in valuating th rsults obtaind that th adoptd ICE coms from th motorcycl industry, which, at last until now, was vry focusd on prformanc improvmnt and wight rduction but not in th sam way to limit th ful consumption. An ngin dsignd to this purpos, or disl or gas fd, could nabl still lowr consumptions than thos achivd with Urb-. n Urb- would also b an xampl to ncourag small producrs to us hybrid architctur. This is suitabl to mploy commrcial componnts, and thir assmbly rquirs no cost-prohibitiv manufacturing facilitis. In fact, th production of a sris hybrid city car is affordabl vn to small businsss littl mor than handicraftsman. n An illustration of th control stratgy has bn givn. Th sris hybrid allows a wid possibility of dsign and softwar dvlopmnt. Acting on it is possibl, with littl xpns, to gt grat savings on vhicl oprating costs. Th sris hybrid also allows customization of th program by working on th paramtrs that can b asily changd. In this way, bsids allowing a rspons of th car bst suitd to th prsonality of th drivr, you can calibrat th charactristics of th traction systm on th road mission. This is particularly usful in a cas of rptitiv us of th vhicl or in fixd routs whn th car is working as a public srvic. Following ths considrations, it can b considrd that th proposd sris hybrid configuration has provn to b an ffctiv solution applicabl to city cars. Knowldg and dissmination of this tchnology can bcom an important tool in th hands of dsignrs to improv th conomic and productiv systm of th automobil industry. Author Information Ennio Rossi (nnio.rossi@na.it) graduatd in mchanical nginring at th Univrsity La Sapinza of Rom in 98. H joind ENEA in 98 and until 99 workd in th wind nrgy fild. From 99, h has bn involvd in lctric and hybrid vhicls. H is currntly working in a program of ralization of prototyps of hybrid vhicls. H has publishd 8 articls on clan mobility. Carlo Villant (carlo.villant@na.it) compltd his Ph.D. dgr and is a mchanical nginr of thrmal machins, with a spcial focus on LPG-fuld ICEs. H is a univrsity rsarchr of ICEs and rnwabl sourcs, univrsity profssor of rnwabl nrgy sourcs, formr profssor of safty in industrial plants, and a rsarchr in ENEA. H is involvd in hybrid vhicls and mobility systms group and is an author of mor than tchnical paprs. Rfrncs [] Di Napoli and G. Pd, Hybrid storag systm: An optimization cas, SAE papr --9. [] F. Caricchi, F. Crscimbini, F. G. Capponi, and L. Solro, Study of bidirctional buck-boost convrtr topologis for application in lctrical vhicl motor drivs, in Proc. th IEEE Applid Powr Elctronics Conf. and Exposition, Anahim, Fb [] S. Brsali, M. Craolo, and A. Possnti, Tchniqus to control th lctricity gnration in a sris hybrid lctrical vhicl, IEEE Trans. Enrgy Convrsion, vol., no., pp., Jun. [] G. Pd, E. Rossi, R. Vllon, R. Giglioli, and M. Craolo, Esprinz di controllo studi di ottimizzazion nrgtica pr un vicolo ibrido sri, RT///IDROCOMB ENEA. DECEMBER IEEE VEHICULAR TECHNOLOGY MAGAZINE