Fuel-efficient state of charge control in hybrid electric vehicles

Load point shifting of the internal combustion engine in hybrid electric vehicles is used to control the state of charge of the high voltage battery. The control strategy has a significant impact on the achievable fuel savings. This paper presents a method, which controls load point shifting for all useable operating points of the power train by balancing cost and benefit considerations, i. e. current power expenditure versus potential future savings. The control method proposed encompasses offline as well as online optimization. Furthermore, industrial requirements such as processor calculation cycles and reduced tuning complexity are considered.