Powertrain Design Alternatives for Electric City Bus

The objective of this paper is to analyze the performance characteristics of different powertrain design alternatives in electric city bus. These powertrain alternatives are generated with different configurations of energy storage system, traction motor and transmission. Ultracapacitors and lithium based batteries are used as energy storages and induction and permanent magnet electric motors as traction motors. Simulations were performed in four different city bus driving cycles. Specific simulations were carried out for investigating the impact of the weight and auxiliary power on the energy consumption. The simulation results indicate that the powertrain efficiency and high potential for regenerating braking energy have significant impact on overall energy efficiency of the electric city bus. It was also observed that the most of the powertrain alternatives are well adapted for all simulated driving cycles. The driving cycle mainly impacts on the potential for regenerating the braking energy. The simulation results also show that higher auxiliary power consumption has much more influence on the overall energy consumption than increased weight of the bus.