Assessment of behavior of Active EDLC-Battery system in Heavy Hybrid Charge Depleting Vehicles

This paper investigates the possibilities of the implementation of an EDLC system when used as a power buffer for the smoothening of rapid power fluctuations in- and out of the batteries in multi-use heavy-duty battery electric vehicles. The study describes the design of EDLC-based energy storage as peak power unit as well as its management strategy. This management strategy is crucial in order to achieve high vehicle efficiency, to obtain dynamic performance during acceleration, and to increase the battery life cycle. The proposed management strategy results in load leveling the batteries and having the EDLCs accept all the regenerative braking energy. In this paper, a simulation model of an active EDLC-battery system is presented for several battery technologies. This study proposes a control strategy which is based on a moving average power control. In this work, aspects as autonomy, energy efficiency of the driveline and stabilization of the DC-bus voltage have been investigated. Then, an experimental prototype of a hybrid system is built and tested. The experimental results verified the validity of the proposed approach. It is shown that relatively low power batteries such as lead-acid batteries as well as high energy lithium batteries combined with EDLCs provide good vehicle performance with much reduced stress on the batteries. Finally, accelerated life cycle tests showed a substantial improvement for stand-alone lead-acid battery packs resulting in a lifetime enhancement with 30%. Moreover, the lifetime of lithium-ion batteries is increased with 1105%.

Publication year:2010

Keywords:Battery, EDLCs, Control strategy