Power Management for Hybrid Energy Storage System of Electric Vehicles Considering Inaccurate Terrain Information

Terrain information can significantly impact load power demand, and in turn, on battery life and system efficiency of a hybrid energy storage system (ESS) with battery and supercapacitor. Taking terrain information ahead into consideration for proactive power management is one of the most important ways to improve battery life and overall system efficiency. However, since terrain information is typically available from commercial geographic information systems database, it is by nature inaccurate with uncertainties with respect to the requirements of power management. This is often worsening when combining with commercially low-quality global positioning systems. This paper proposes a novel power management strategy to cope with the inaccuracy and uncertainties of the terrain information with the aim to improve battery life, while maintaining overall system performance. First, the impact of terrain inaccuracy on battery life and system efficiency is analyzed based on two different hybrid ESSs with semiactive topologies. Then, a power management control strategy is developed that actively distributes the power between battery and supercapacitor with adaptation to terrain inaccuracy and uncertainties. The objective of the proposed power management control strategy is to minimize the total cost of the system, including the cost for battery life and energy. Finally, simulation is conducted that has verified the effectiveness of the proposed control strategy. Note to Practitioners-Recently, advanced technologies in geographic information systems and global positioning systems have supplied more opportunities for the prediction of future driving conditions, which will help more reasonable use of the system power demand by extending the planning horizon. However, the inaccuracy and uncertainties of prediction information could have an important effect on the HESS with battery and supercapacitor. This paper contributes to a better understanding of the details of the impacts of the inaccuracy and uncertainties of the terrain information on battery life and system efficiency based on two different hybrid energy storage systems with semiactive topologies, and furthermore, a novel power management strategy is developed to deal with inaccuracy and uncertainties. The results of this paper will be useful for a practical implement of an HESS for battery life and system efficiency improvement.