Outline. Vehicle Propulsion Systems Vehicles as a hot topic is everlasting A diversity of powertrain configurations is appearing

Transcription

1 Lecture 1 Course ntrouction & Energy System Overview Lars Eriksson Professor Analyzing Energy Deman for a Vehicle Energy Deman of Driving Missions Vehicular Systems Linko ping University April 6, / 35 2 / 35 Vehicles as a hot topic is everlasting A iversity of powertrain configurations is appearing Brings freeom to the user Have a irect influence on the environment Consume resources that are limite Have ifferent appeal to ifferent persons Conventional nternal Combustion Engine (CE) powertrain. Diesel, Gasoline, New concepts Hybri powertrains Parallel/Series/Complex configurations Fuel cell electric vehicles Electric vehicles Course goal: ntrouction to powertrain configuration an optimization problems Mathematical moels an methos for Analyzing powertrain performance Optimizing the powertrain energy consumption 5 / 35 4 / 35 Top Priorities in Vehicle Development The vehicle in focus is passenger cars. (n the book.) What characterizes passenger cars? mprove the fuel economy of vehicles (Better cars are our best oil-wells) Reuce costs Drivability Safety Emissions Vehicle properties Exhaust emissions Roa ust Noise Legislations Autonomous an o not epen on fixe power gri. Have refueling time negligible compare to the riving time between two refuelings. Transport two to six persons an some payloa. Accelerate from 0 to 100 km/h in secons, or rive uphill a 5% ramp at legal top spee. Methos an tools are also applicable to trucks an other transportation systems. All issues are important but the first item is the main topic here. Numerical values iffer Demans are ifferent Principles are the same but solutions iffer 6 / 35 Life Cycle of a Vehicle Primary Energy Sources 7 / 35 nfrastructure Fuel Manufacturers Sources of Raw Material Car Manufacturers Governments at all Levels Fuel Distribution En Customer Analyzing Energy Deman for a Vehicle Distribution Repair an Maintenance Energy Deman of Driving Missions Scrapping an Recycling Many things are important! Focus is on energy path an in-vehicle energy conversion 8 / 35 9 / 35

2 Examination 5 (3) Han-n Assignments Han-n assignments one iniviually. Compenium for Han-n assignments. 1. Fuel consumption requirement of a riving mission. Methos an tools for estimating the fuel consumption. Manatory an optional tasks. 2. Optimal control of series an hybri concepts. Tools for investigating the best possible riving scheule. Manatory an optional tasks. 3. ECMS base on-line control of a parallel hybri. Stanar optimal control base controller. Manatory an optional tasks. 4. Three concepts for short term energy storage. Very open ene problems. Optional tasks. 5. Fuel cell vehicle. Optional tasks. 10 / 35 Examination Graing system 1. Pass Grae 3. All manatory tasks must be complete. Hane in, examine, returne (correcte, hane in again, until pass). 2. Higher graes. Hane in, grae by us (like an exam), returne. Point system connecte to extra tasks. Grae p Grae 4 14-? p Grae 5 24-? p 3. More etails are foun in the compenium. Dealines given on the home page. 11 / 35 Resources Course Computer tools are necessary, to be able to solve interesting problems. Matlab an Simulink with extra packages. f you have your own computer, we encourage you to use it. 2 computer room booke on 2 occasions per week We (17-21), an Friay See it as support opportunity. Lab room assistant, answers questions. Collect your questions an come to us. Preparations for han-in Refresh your knowlege Matlab an Simulink programming experience. Let s have a look on the course home page! 12 / / 35 Energy System Overview Primary sources Analyzing Energy Deman for a Vehicle Energy Deman of Driving Missions Different options for onboar energy storage Powertrain energy conversion uring riving Cut at the wheel! Driving mission has a minimum energy requirement. 14 / / 35 Example of Some Energy Paths W2M Analyzing Energy Deman for a Vehicle Energy Deman of Driving Missions 16 / / 35

3 Repetition Work, power an Newton s law Remember the partitioning Cut at the wheels. How large force is require at the wheels for riving the vehicle on a mission? Translational system Force, work an power: W = F x, P = t W = F v Rotating system Torque (T = F r), work an power: W = T θ, P = T ω Newton s secon law: Translational t = F riv F loa Rotational J ω t = T riv T loa 18 / / 35 Newton s secon law for a vehicle t v(t) = F t(t) (F a (t) + F r (t) + F g (t) + F (t)) Fr F t tractive force F a aeroynamic rag force F r rolling resistance force F g gravitational force F isturbance force Fg mv g Fa F Aeroynamic Drag Force Loss Aeroynamic rag force epens on: Frontal area A f, rag coefficient c, air ensity ρ a an vehicle velocity v(t) Approximate contributions to F a 65% car boy. 20% wheel housings. F a (t) = 1 2 ρ a A f c v(t) 2 10% exterior mirrors, eave gutters, winow housings, antennas, etc. 5% engine ventilation. 20 / / 35 Rolling Resistance Losses Rolling resistance epens on: loa an tire/roa conitions F r (v, p t, surface,...) = c r (v, p t,...) g cos(), v > 0 Gravitational Force Gravitational loa force Not a loss, storage of potential energy Fa F Fg Fr mv g Up- an own-hill riving prouces forces. The velocity has small influence at low spees. ncreases for high spees where resonance phenomena start. Assumption in book: c r constant F r = c r g 22 / 35 F g = g sin() Flat roa assume = 0 if nothing else is state (n the book). 23 / 35 nertial forces Reucing the Tractive Force Vehicle Operating Moes Te ωe Engine Gearbox Wheel Jw ωw : t v(t) = F t(t) (F a (t) + F r (t) + F g (t) + F (t)) Je T e J e t ω e = T gb γ Tt T gb γ J w t ω w = T t F t > 0 traction F t < 0 braking F t = 0 coasting Variable substitution: T w = γ T e, ω w γ = ω e, v = ω w r w Tractive force: [ ] ( ) F t = 1 v(t) (T e J e t γ) γ Jw v(t) t = γ Te γ 2 J 2 e + 1 J 2 w t v(t) The Vehicle [ Motion Equation: ] + γ2 J 2 e + 1 J 2 w t v(t) = γ Te (Fa(t) + Fr (t) + Fg (t) + F(t)) t v(t) = 1 ρ a A f c v 2 (t) g c r = 2 v 2 (t) β 2 2 Coasting solution for v > 0 v(t) = β tan (arctan ( ) ) β v(0) β t 24 / / 35

4 How to check a profile for traction? : t v(t) = F t(t) (F a (t) + F r (t) + F g (t) + F (t)) (1) Traction conitions: F t > 0 traction, F t < 0 braking, F t = 0 coasting Metho 1: Compare the profile with the coasting solution over a time step v coast (t i+1 ) = β ( ) ) (arctan tan β v(t i) β (t i+1 t i ) Metho 2: Solve (1) for F t F t (t) = t v(t) + (F a(t) + F r (t) + F g (t) + F (t)) Numerically ifferentiate the profile v(t) to get t v(t). Compare with Traction conition. 26 / 35 Driving profiles Velocity profile, American FTP-75 (1.5*FUDS). Driving profiles in general First use for pollutant control now also for fuel consumption. mportant that all use the same cycle when comparing. Different cycles have ifferent energy emans. 27 / 35 Driving profiles Another example Mechanical Energy Deman of a Cycle Velocity profile, European MVEG-95 (ECE*4, EUDC) No coasting in this riving profile. Only the eman from the cycle The mean tractive force uring a cycle F trac = 1 xtot where = t max 0 v(t)t. Note t trac in efinition. Only traction. 0 ling not a eman from the cycle. max(f (x), 0) x = 1 F (t)v(t)t t trac 28 / / 35 Evaluating the integral Discretize velocity profile use to evaluate F trac = 1 F (t)v(t)t t trac here v i = v(t i ), t i = i h, i = 1,..., n. Approximating the quantites v i (t) v i + v i 1, t [t i 1, t i ) 2 ā i (t) v i v i 1, t [t i 1, t i ) h Traction approximation F trac 1 F trac,i v i h Evaluating the integral Tractive force from F trac = 1 2 ρ a A f c v 2 (t) + g c r + a(t) Resulting in these sums F trac = F trac,a + F trac,r + F trac,m F trac,a = ρ a A f c v 3 i h F trac,r = 1 g c r v i h F trac,m = 1 ā i v i h 30 / / 35 Values for cycles Approximate car ata Numerical values for the cycles: X trac,a = 1 X trac,r = 1 X trac,m = 1 {MVEG-95, ECE, EUDC} v 3 i h = {319, 82.9, 455} v i h = {0.856, 0.81, 0.88} ā i v i h = {0.101, 0.126, 0.086} Ē MVEG-95 A f c c r SUV full-size compact light-weight PAC-Car A f c 1.2 m m m m m 2 c r kg 1500 kg 1000 kg 750 kg 39 kg P MVEG kw 7.1 kw 5.0 kw 3.2 kw P max 155 kw 115 kw 77 kw 57 kw Average an maximum power requirement for the cycle. kj/100km Ē MVEG-95 A f c c r Tasks in Han-in assignment kj/100km 32 / / 35

5 Energy System Overview Primary sources Different options for onboar energy storage Powertrain energy conversion uring riving Cut at the wheel! Driving mission has a minimum energy requirement. 34 / 35