Enhancing Battery Pack Capacity Utilization in Electric Vehicle Fleets via SoC-Preconditioning

Abstract

Modern public transport solutions based on autonomous electric vehicles are on the rise. Public transportation as a service on demand is becoming a reality. Therefore, vehicles suitable for these kinds of applications need to be developed. One critical factor for such vehicles is a short turnaround time at the charging spot. Maximizing the utilization of a given battery pack capacity and minimizing the time spent charging are therefore of central importance. In this paper, we propose a novel preconditioning algorithm to minimize the time an EV is connected to the charging station. Our proposed approach uses existing Active Cell Balancing (ACB) hardware of the battery pack to precondition the State of Charge (SoC) of cells such that all cells reach the top SoC threshold at the same time without requiring an additional balancing phase during charging. This is done by considering the individual cells' charging rate to precondition them for achieving an equal time to full charge. Applying the same approach for discharging, we also extend the driving range of an EV, which otherwise is limited by the cell with the lowest SoC in the pack. Case studies show that our proposed preconditioning algorithm increases the usable energy of the battery pack by up to 3% compared to conventional balancing algorithms all while effectively halving the time connected to a charging station, all without requiring any additional hardware components.