A four stage energy control strategy and fuel economy simulation for extended-range electric city bus

Because of the high cost of battery, lack of charging infrastructure and limitation of range, EVs are hard to be accepted by ordinary customers recently. Compared with EVs, range extender EVs should allow vehicle weight reduction, manufacturing cost reduction, and dramatic range extension. For most driving conditions, the range of E-REVs subjected to the same limitation as traditional internal combustion engine vehicles. Recently, our research group designed the power train and vehicle energy control strategy for an electric city bus which has a range extender composed of a gasoline engine and a generator. In this paper, a four stage energy control strategy applied to the bus is introduced. Based on the driving distance is fixed or can be forecasted, the strategy aims to optimize vehicle equivalent fuel economy by controlling APU output power to let the battery work on high discharge and charge efficiency state during the most time of driving process, and the battery SOC should maintain a low level at the end of the driving cycle. The vehicle equivalent fuel consumption is simulated by using a real time vehicle simulation platform. The simulation results show that four stage control strategy can make the bus save 0% to 2.7% of fuel consumption compared to CDCS strategy according to different mileage.