Drive Train Analysis and Vehicle Dynamics for the c,mm,n 2.0 R.P.C. van Dorst, B.J.H van Laarhoven R.A.M Meesters, M.W.F. Mol DCT 2008.142 Master Team Project report Coaches: dr.ir. I.J.M. Besselink dr.ir. T. Hofman Supervisor: prof.dr. H. Nijmeijer Technische Universiteit Eindhoven Department Mechanical Engineering Dynamics and Control Technology Group Eindhoven, November, 2008 Abstract The c,mm,n project was initiated in 2005 by the foundation of Nature and Environment (Stichting Natuur en Milieu, SNM) as an answer to the 2005 AutoRAI, where there was little attention for environmentally friendly cars. SNM asked the help of the three universities of technology in the Netherlands to develop a sustainable car for the future. This first phase of the c,mm,n project is called c,mm,n 1.0 and many aspects of the c,mm,n 1.0 car became research topics for graduate students. The results of c,mm,n 1.0 were presented at the 2007 AutoRAI. In November 2007, the c,mm,n 2.0 project was launched. SNM plans to make a new presentation of c,mm,n 2.0 on the 2009 edition of the AutoRAI with the desire to show a driveable prototype. To assist SNM in this task, this report presents a new drive train option which is analyzed and compared to the two c,mm,n 1.0 drive trains. Additionally, the vehicle dynamics of the c,mm,n vehicle are analyzed. The two c,mm,n 1.0 drive trains are a fuel cell supercapacitor hybrid (FCSCH) drive train and an internal combustion engine with cylinder deactivation (ICE) drive train. Because the drive train for an electric vehicle features less energy conversion steps than a hybrid drive train and contains drive train components which all work at high efficiency (>90%), this drive train option was investigated. The new drive train option is therefore an electric vehicle (EV) drive train. It consists of four in-wheel electric motors, a battery pack, power electronics and optionally a solar panel and/or range extender. The electric motors are chosen to meet the requirement that acceleration from 0 to 100 km=h must be possible in under 12 seconds. The size of the battery pack is based on a range requirement which dictates that the autonomous range of the vehicle should be at least 300 km. A range extender which could be placed modularly (i.e. as an additional component that can be added or removed at will) can be an interesting option, because when the c,mm,n is used for transportation to a distant place (e.g. going on vacation), the battery pack range will not be sufficient. For these long distance trips a range extender can be used, such as small fuel cell or an internal combustion engine with an electric generator. To do a simulation of the EV drive train, the QSS Toolbox is used. It can give insight to the influence of regenerative braking on the battery state of charge and the operating points of the electric motor. A drawback of the QSS Toolbox is that not all parameters can be changed easily. It is therefore not possible to simulate with the correct component sizes, which makes the results inaccurate for a quantitative analysis, but still useful as a qualitative analysis. A multi criteria analysis can make clear what drive train option is the preferable drive train for the future. The conclusion of this MCA is that a hydrogen powered vehicle (FCSCH) can be cheaper and more sustainable than an ICE powered vehicle, but this is based on the expectancy that fuel cell prices and hydrogen prices will drop significantly. This will only happen if a global hydrogen economy is realized. When maximizing sustainability the EV has no competition, because of its high well to wheel efficiency. The weak point of the EV is its shorter autonomous range. The vehicle dynamics of the c,mm,n vehicle is investigated by means of simulations using the SimMechanicsTM and Delft-Tyre toolbox of MATLAB R . A SimMechanicsTM model of the EV c,mm,n vehicle simulates the vehicle driving on specific road profiles and some specific manoeuvres. The model contains an active suspension which reduces the pitch and roll motion of the vehicle. Simulation results are compared for a passive suspension setup versus an active suspension setup. The passive suspension setup is identical to the active suspension, but with fixed secondary arm (there is no secondary spring influence). It should be noted that this passive suspension is therefore not the best possible representation of a passive suspension. The analysis does, however, point out the contribution of the active suspension to the vehicle dynamics. In all simulated manoeuvres, the active suspension keeps the vehicle significantly more leveled than the passive suspension does. 1 List of abbreviations abbreviation description CNG Compressed Natural Gas CO2 Carbon Dioxide DC Direct Current EM Electric Motor ESP Electronic Stability Program EUDC Extra-Urban Driving Cycle EV Electric Vehicle FC Fuel Cell FCSCH Fuel Cell Super Capacitor Hybrid ICE Internal Combustion Engine LiCoO2 Lithium Cobalt Dioxide LiFePO4 Lithium Iron Phosphate MCA Multi Criteria Analysis NEDC New European Driving Cycle NiMH Nickel Metal Hydride PEM Proton Exchange Membrane PLIB Polymer Lithium-Ion Battery PP Power Plant PSD Power Spectral Density QSS Quasi Static Scheduling RAI Rijwiel en Automobiel Industrie RMS Root Mean Square SC Super Capacitor SNM Stichting Natuur en Milieu SOC State of Charge TU/e Technische Universiteit Eindhoven 2 List of symbols symbol description unit η understeer coefficient − ηcycle cycle efficiency − a distance from front wheels to COG m 2 Af frontal area m b distance from COG to front wheels m C1 cornering stiffness front tyres N=rad C2 cornering stiffness rear tyres N=rad ds suspension damper constant Ns=m dsky skyhook damper constant Ns=m e energy density J=l or J=kg Echarge energy transferred for charging J Econs energy consumption MJ=km Ecost energy cost e=MJ Edemand vehicle energy demand MJ=km Edischarge energy transferred for discharging J Feconomy fuel economy e=km f frequency Hz feig eigen frequency Hz ∆Fz vertical tyre force N g gravitational constant m=s2 ks suspension spring constant N=m kt tyre spring constant N=m m vehicle mass kg ma unsprung mass kg ms sprung mass kg mtank tank mass kg 6 pitch body pitch angle deg 6 roll body roll angle deg s vehicle range km SOC state of charge for battery pack − T torque Nm t time s V vehicle speed km=h Vtank tank volume l xsusp suspension travel mm za unsprung mass displacement m zr road height m zs sprung mass displacement m 3 Contents 1 Introduction 5 1.1 A brief history of c,mm,n....................................5 1.2 The challenges for the c,mm,n 2.0................................5 1.3 Structure of this report.....................................5 2 Drive trains 7 2.1 Design requirements.......................................7 2.2 Fuel cell supercapacitor hybrid (FCSCH)...........................8 2.3 Internal combustion engine (ICE)................................8 2.4 The electric vehicle (EV).................................... 10 3 Multi Criteria Analysis 17 3.1 Mass................................................ 17 3.2 Energy consumption....................................... 18 3.3 Fuel economy........................................... 18 3.4 Range............................................... 20 3.5 Environmental load........................................ 20 3.6 Lifecycle costs........................................... 21 3.7 Packaging............................................. 22 3.8 Conclusion............................................ 22 4 Vehicle dynamics 23 4.1 Active Suspension........................................ 23 4.2 Recommendations for further research............................. 31 5 Conclusions & recommendations 33 A c,mm,n specifications 34 B Packaging 36 4 Chapter 1 Introduction 1.1 A brief history of c,mm,n The foundation for Nature and Environment ("Stichting Natuur en Milieu", SNM) was the initiator for the project "A Car in the Future". The project started in August 2005, by challenging the three universities of technology of the Netherlands (Eindhoven, Delft and Twente) to design a sustainable car for the future. This as an answer to the 2005 AutoRAI, where very little attention was given to cars that are developed to be less harmful to the environment. The upcoming concerns about global warming through CO2 emissions due to cars and the attention SNM wanted to focus on this problem caused them to make a statement to the car industry. SNM wanted them to show an example of a clean, clever and quiet car so as to encourage the car manufacturers to quickly start mass production of green cars. After a short inquiry at the three universities of technology of the Netherlands, it proved to be better to combine the efforts of the three universities instead of having them compete with each other. The car of the future project involves the design of the exterior, interior, suspension system and power train of a future car within the context of the community in 2020. The mechanical engineering division of the Eindhoven University of Technology (TU/e) was asked to develop the complete suspension and power train system of what is called, the c,mm,n vehicle. [1] The result was shown at the AutoRAI 2007 and received a lot of media attention. For more information, the reader may visit http://www.cmmn.eu or http://www.cmmn.org. In November 2007, the c,mm,n 2.0 project was officially launched. In February 2008, the first "c,mm,n garage" was held. This is an event in which anyone interested in c,mm,n may come and see what it is about and contribute to the project. This first c,mm,n garage coincided with the start of this master team project and visiting this garage showed the variety of different ideas that surround c,mm,n and introduced the people that are active in the c,mm,n project.