Fuel cells and high energy density batteries have limited overrated capacity and slow power response. Ultracapacitors and flywheels are proposed to overcome these limitations and to facilitate regenerative braking in hybrid and electric vehicles. The simulations presented in this paper show that a Secondary Energy Storage Unit (SESU) enhances the performance of the drivelines as previously suggested and provides additional improvements. A combined design of the primary energy source and the SESU reduces the total weight and volume and increases the battery lifetime. A full-electric driveline is simulated using a standard EPA FTP-75 drive cycle. Then the same vehicle is simulated with as SESU and the results are compared. The same is done for a hybrid driveline. Two drivelines are used as references and then enhanced with an SESU; four simulations are presented in total. Simulation results show that an energy storage device with very low energy and high power allows better battery selection and energy management. 1. Introduction Research in electric vehicles has a long history full of success and disappointment. There are great expectations that are fulfilled only recently with the latest developments in batteries. Batteries are the most challenging component of the electric car. Energy density is very low compared to gasoline. Electric cars have less range than gasoline as batteries become very heavy. Most commercial electric cars are intended for commuting purposes with an average range of less than 160？km [1]. The Tesla Model is the commercial electric car with higher range up to 480？km (300 miles) and the battery alone weighs 600？kg [2]. The battery is also an expensive component. Different forecasts agree that the price of future electric cars will be at least $5,000 higher than conventional petrol cars even with scale economies [3]. The power and energy density is a compromise of the reagents density. There are batteries with high power density, but their energy density is limited. There are batteries with high energy density, but the power density is compromised. A Secondary Energy Storage Unit (SESU) has been proposed to improve the dynamic response of drivelines [4, 5]. This paper argues that SESUs have a positive economic potential when the complete driveline is evaluated. A power buffer is here defined as a component that can provide high power for short periods of time without compromising its lifetime. The power buffer would not be the main energy source but work in combination with Internal Combustion Engines (ICEs) or batteries.
References
[1]
J. de Santiago, H. Bernhoff, B. Ekerg？rd et al., “Electrical motor drivelines in commercial all-electric vehicles: a review,” IEEE Transactions on Vehicular Technology, vol. 61, no. 2, pp. 475–484, 2012.
L. Cheah and J. Heywood, “The cost of vehicle electrification: a literature review,” in Proceedings of the MIT Energy Initiative Symposium, Sloan Automotive Laboratory, Massachusetts Institute of Technology, Cambridge, Mass, USA, April 2010.
[4]
B. Szabados and U. Schaible, “Peak power bi-directional transfer from high speed flywheel to electrical regulated bus voltage system: a practical proposal for vehicular technology,” IEEE Transactions on Energy Conversion, vol. 13, no. 1, pp. 34–41, 1998.
[5]
S. Mallika and R. Saravana Kumar, “Review on ultracapacitor—battery interface for energy management system,” International Journal of Engineering and Technology, vol. 3, no. 1, pp. 37–43, 2011.
[6]
M. Roberts, P. Johns, J. Owen et al., “3D lithium ion batteries—from fundamentals to fabrication,” Journal of Materials Chemistry, vol. 21, no. 27, pp. 9876–9890, 2011.
M. Steiner, M. Klohr, and S. Pagiela, “Energy storage system with Ultracaps on board of railway vehicles,” in Proceedings of the European Conference on Power Electronics and Applications (EPE '07), September 2007.
F. N. Werfel, U. Floegel-Delor, T. Riedel et al., “250 kW flywheel with HTS magnetic bearing for industrial use,” Journal of Physics: Conference Series, vol. 97, no. 1, Article ID 012206, 2008.
P. H. Mellor, N. Schofield, D. Howe, and Flywheel a, “nd supercapacitor peak power buffer technologies,” in Proceedings of the IEE Seminar on Electric, Hybrid and Fuel Cell Vehicles, pp. 1–5, Durham, UK, 2000.
[20]
S. Pay and Y. Baghzouz, “Effectiveness of battery-supercapacitor combination in electric vehicles,” in Proceedings of the Power Tech Conference, pp. 1–6, Bologna, Italy, 2003.
[21]
T. A. Smith, J. P. Mars, and G. A. Turner, “Using supercapacitors to improve battery performance,” in Proceedings of the IEEE 33rd Annual Power Electronics Specialists Conference (PESC '02), pp. 124–128, June 2002.
[22]
Y.-P. Yang, J.-J. Liu, and T.-H. Hu, “An energy management system for a directly-driven electric scooter,” Energy Conversion and Management, vol. 52, no. 1, pp. 621–629, 2011.
[23]
J. Dixon, M. Ortuzar, and E. Wiechmann, “Regenerative braking for an electric vehicle using ultracapacitors and a buck-boost converter,” in Proceedings of 17th International Electric Vehicle Symposium, pp. 1–6, Montreal, Canada, 2000.
[24]
I. Hadjipaschalis, A. Poullikkas, and V. Efthimiou, “Overview of current and future energy storage technologies for electric power applications,” Renewable and Sustainable Energy Reviews, vol. 13, no. 6-7, pp. 1513–1522, 2009.
[25]
G. Pistoia, Battery Operated Devices and Systems, Elsevier, 2008.
[26]
J. Cibulka, “Kinetic energy recovery system by means of flywheel energy stor- age,” Advanced Engineering, vol. 3, no. 1, pp. 27–38, 2009.
[27]
A. Barin, L. N. Canha, A. Da Rosa Abaide, and K. F. Magnago, “Selection of storage energy technologies in a power quality scenario—the AHP and the fuzzy logic,” in Proceedings of the 35th Annual Conference of the IEEE Industrial Electronics Society (IECON '09), pp. 3615–3620, November 2009.
[28]
X. X. Fu and X. Xie, “The control strategy of flywheel battery for electric vehicles,” in Proceedings of the IEEE International Conference on Control and Automation (ICCA '07), pp. 492–496, June 2007.
[29]
P. Shakouri, A. Ordys, P. Darnell, and P. Kavanagh, “Fuel efficiency by coasting in the vehicle,” International Journal of Vehicular Technology, vol. 2013, Article ID 391650, 14 pages, 2013.
[30]
B. Mecrow, J. Bennett, A. Jack, D. Atkinson, and A. Freeman, “Very high efficiency drives for solar powered unmanned aircraft,” in Proceedings of the International Conference on Electrical Machines (ICEM '08), September 2008.
[31]
R. Shankar, J. Marco, and F. Assadian, “The novel application of optimization and charge blended energy management control for component downsizing within a plug-in hybrid electric vehicle,” Energies, vol. 5, no. 12, pp. 4892–4923, 2012.
[32]
“K2 SERIES 650 F-3, 000 F ULTRACAPACITORS,” Data Sheet, Maxwell Technologies, San Diego, Calif, USA.
