Advanced Energy Management Strategies for Range Extended Electric Vehicle 2015-26-0121
Statistical studies have shown that many electric vehicles existing in the market today can cater to most typical daily driving trips. However where such vehicles are sometimes found wanting are the occasional trips beyond the available electric vehicle range, or unexpected trips when the battery is already in a discharged state. These circumstances necessitate either maintaining a second internal combustion engine powered car or use of public transport. An alternative to this is the use of a range extended electric vehicle (REEV). A REEV can operate in two modes, either as an electric vehicle on short journeys or as a series hybrid with the aid of a small auxiliary power unit (APU) when the battery energy is low over longer distances. The addition of an APU eliminates the range anxiety experienced by electric vehicle owners by extending the range possible in a single charge. The total range of the REEV can be further enhanced by energy management strategies that enable efficient use of fuel energy during APU operation. An important factor for a REEV is NVH. The difference in noise output from the vehicle when the APU is operating can result in poor driving experience in the REEV as the electric vehicle operation is quieter compared to the internal combustion engine (ICE) operation. In this study two advanced energy management strategies are described that both increase vehicle range through improved fuel economy, as well as attempting to minimise noise during APU operation. This paper describes the development of a simulation model of the REEV, the energy management strategies used along with a description of how to optimize them for real world driving.