Towards Electrification of Urban Buses Using Model Based Analysis 2018-01-0408
City buses electrification gains increasing interest as a promising solution for both zero emissions in urban environment and energy consumption minimization. Nevertheless, global spread of battery electric buses may be currently questionable, mainly due to traveling range limitations. In this respect, the aim of this work is to elucidate performance aspects of battery electric powertrain systems for urban buses. Instead of exhaustive testing, cost-effective model based vehicle analysis is proposed for quantifying and understanding electric propulsion system performance and respective vehicle energy consumption. First, an indicative 12-m battery electric urban bus model was developed and its performance was simulated under both steady state conditions, as well as the legislated Braunschweig driving cycle. To get more insight into traveling range controlling factors, sensitivity analysis was performed regarding energy consumption related to passengers load, cabin air-conditioner operation and transmission system design. Overall, simulation results tend to support electric buses high performance in terms of top speed and gradeability at limited energy consumption. On the other hand, auxiliary units operation and transmission system configuration may require optimization to achieve sufficient travelling range.