Feasibility Study of Supercapacitors as Stand-Alone Storage Systems for Series Hybrid Electric Vehicles

Hybrid Electric Vehicles are gaining more and more popularity nowadays and thanks to the recent performance improvements of the electric components they can achieve noticeable energy savings. The storage system plays a key role in this scenario, in particular high power permeable storage systems as supercapacitors enable the series architecture to be applied on medium size car obtaining energy saving higher than the ones achievable thanks to standard parallel architectures. However, the low energy density featuring supercapacitors represent the main limitation of this solution if it is conceived as a stand-alone storage system. Indeed, this characteristic can lead to the State of Charge (SOC) saturation, frustrating all the benefits typical of hybrid powertrains. This paper aims therefore at evaluating if a supercapacitor module reasonably sized and employed on series based powertrains (on medium-size car) as the only storage system, can avoid SOC saturation in different road missions.