Ultracapacitor Energy Storage for Improving Fuel Economy and Extending Battery Life in Heavy Vehicles

Project duration: 2012-2014.

The overall goal of this research was to determine, via simulation analysis and laboratory experiments, the circumstances in which ultracapacitors provide power, weight, or cost advantages when used stand-alone or along with batteries in military vehicles. Our objective, based on our new experimental results, was to determine advantages that ultracapacitors provide when hybridized with lead-acid or Li-ion batteries, in particular at low temperatures.

Over the course of this project the focus was on modeling, hybridization, and optimal charging of electrical energy storage systems. At the beginning of the research, stand-alone supercapacitors were studied in order to facilitate the integration of them in a wide variety of power applications. The approach was to understand the electrical and thermal dynamics of supercapacitors in a wide range of temperature and loads via modeling, parameterization, and experimental validation. The second part of the project included investigating the benefits of hybridizing batteries via supercapacitors. The goal was to improve the range of a fully electric vehicle powered by lead-acid batteries. A model for a lead-acid battery was developed and integrated with the supercapacitor model developed in the first study to build the hybrid energy storage model. Hardware in the loop experiments were conducted to validate the results. Our research has focused on the slow and fast charging problem for of supercapacitors as well as lithium-ion and lead-acid battery energy storage systems. Utilizing optimal control theory we shed light on the achievable charging efficiencies while considering long and short charging times, voltage and current constraints, and also thermal dependency of model parameters.

Collaboration with other ARC efforts included:

• Electro-Thermal Modeling of Cylindrical Supercapacitors, in collaboration with Professor Anna Stefanopoulou’s Group at the University of Michigan, and
• Hybridization of a Lead-Acid Battery Using Supercapacitors for Range Extension of a Battery Driven Vehicle, in collaboration with Professor Thompson’s Group at the University of Michigan.

Publications:

• Parvini, Y.; Vahidi, A., “Maximizing Charging Efficiency of Lithium-Ion and Lead-Acid Batteries Using Optimal Control Theory”, in American Control Conference (ACC) 2015, pp.317-322, 1-3 July 2015 doi: 10.1109/ACC.2015.7170755
• Parvini, Y.; Siegel, J.B.; Stefanopoulou, A.G.; Vahidi, A., “Preliminary results on identification of an electro-thermal model for low temperature and high power operation of cylindrical double layer ultracapacitors,” in American Control Conference (ACC) 2014, pp.242-247, 4-6 June 2014 [doi: 10.1109/ACC.2014.6859394](http://dx.doi.org/doi: 10.1109/ACC.2014.6859394)
• Parvini, Y.; Vahidi, A.; , “Optimal charging of ultracapacitors during regenerative braking,” Electric Vehicle Conference (IEVC), 2012 IEEE International, pp.1-6, 4-8 March 2012 doi:10.1109/IEVC.2012.6183291
• Schepmann, S.; Vahidi, A., “Heavy vehicle fuel economy improvement using ultracapacitor power assist and preview-based MPC energy management,” American Control Conference (ACC), 2011, pp.2707-2712, June 29 2011-July 1 2011 doi: 10.1109/ACC.2011.5991098
• Rotenberg, D.; Vahidi, A.; Kolmanovsky, I., “Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, and the Impact on Fuel Economy,” Control Systems Technology, IEEE Transactions on , vol.19, no.3, pp.576-589, May 2011
  doi:10.1109/TCST.2010.2048431
• Hoseinali Borhan and Ardalan Vahidi, “Model predictive control of a hybrid electric powertrain with combined battery and ultracapacitor energy storage system,” International Journal of Powertrain,1 , 351-376, 2012 doi:10.1504/IJPT.2012.049645
• Dean Rotenberg, Ardalan Vahidi, and Ilya Kolmanovsky, “Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, and The Impact on Fuel Economy,” IEEE Transactions on Control Systems Technology, Issue 99, Pages 1-14, 2010.
  doi:10.1109/TCST.2010.2048431
  (earlier results presented in Proceeding of the American Control Conference, Seattle, WA, pp. 981-987, 2008. doi:10.1109/ACC.2008.4586619)

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