A System Analysis and Modeling of a HEV based on Ultracapacitor Battery

There is a clear shift toward the implementation of electrified vehicles in the market, influenced by the introduction of stricter mandatory regulations on fuel economy improvement and emissions reduction. Of these vehicles, the penetration of hybrid vehicles in the market has much potential for growth in the next few years. The adoption of these vehicles has been limited by the high cost of HEV's, which have less uptake in developing regions. Considering this point, developing countries would see the greatest benefit in adopting HEV technology. A mild hybrid system has an observable advantage in these markets due to its maximum benefit/cost ratio when compared to a full hybrid, plug-in hybrid or electric vehicles. This paper discusses the development of a mild hybrid system for such markets with a focus on improving drive performance and efficiency. To achieve this, high power density ultracapacitors are used based on their fast charging and discharging characteristics, together with intelligent drivetrain control taking advantage of the ultracapacitors' characteristics to deliver smooth torque delivery during gear change (torquefilling). A comparison and analysis is undertaken, of both conventional powertrain and an otherwise identical powertrain but for the incorporation of components required for the mild hybrid system. Software models simulated the powertrains in specific driving conditions, with observations made of the advantages of MHEV over conventional drivetrains. The model demonstrated increased fuel efficiency and performance.