Comparison of Particulate Emissions of a Range Extended Electric Vehicle under Different Energy Management Strategies 2019-01-1189

Range extended electric vehicles achieve significant reductions in fuel consumption by employing as an energy source a small displacement combustion engine that is optimized for high efficiency at one, or a few, operating points. The present paper examines the impact of various energy management strategies on the particulate emissions from the auxiliary power unit (APU) of a range extended electric bus, including optimized auxiliary power unit (APU) on/off strategy, single-point strategy, two-point strategy, power-following strategy and equivalent fuel consumption minimization strategy (ECMS). In addition, this paper also compares the particulate emissions of single energy storage system and composite energy storage system on single-point energy management strategy. The main conclusions in this paper are as follows: After optimizing the APU on/off strategy, the APU starts and stops frequently to make the cylinder temperature relatively low, which results in the reductions of both the particle mass (PM) and the particle number (PN). The application of two-point strategy and power-following strategy maximizes the output power of high load, and then the particulate emission presents significant increasing. With the improved ECMS strategy, the mass and quantity of particles have been significantly reduced to 0.49mg/km and 9.57×10¹³#/km. What’s more, the particulate emissions caused by long time and high load are further suppressed. In addition, the composite energy storage system can help to lower the exhaust temperature and the temperature in the cylinder, by extending working gap of the engine. And comparing with the single energy storage system, it shows that the PM and PN of the composite energy storage system are significantly reduced.