Assessment of Behaviour of Super Capacitor-battery System in Heavy Hybrid Lift Truck Vehicles

Abstract

This paper represents an alternative energy storage system in the drive line of a hybrid electric vehicle. The effect of the use of an EDLC (Electrical Double Layer Capacitors) as a power buffer to smooth rapid power fluctuations in and out of the batteries of a hybrid electric heavy truck is investigated. In this work a topology is presented where the performances of a battery pack in parallel with supercapacitors are evaluated in terms of stress and extending battery lifespan. According to this association the battery current drawn is reduced and the supercapacitor source supplies the majority of transient current and as a result the battery stress is reduced up to 30 %. Other laboratory tests showed a fourfold improvement over stand alone lead acid battery pack under a Dynamic Endurance Test in which the lifetime of the battery is increased with 30 %. This work has been carried out on computer simulations. Finally the simulations results are validated on a test bench.