A comprehensive analysis of energy management strategies for hybrid electric vehicles based on bibliometrics

Hybrid electric vehicles (HEVs) are one of the most viable technologies to achieve the goals of energy saving and environmental protection before a breakthrough in battery technology and fuel cell technology. Energy management strategy as a key technology of HEVs is studied extensively and deeply to improve the performance of HEVs and speed up the industrialization of HEVs. This paper quantitatively analyzes and evaluates current research status of energy management strategies for HEVs based on bibliometrics for the first time, through content analysis involving analysis of author keywords and abstracts. Then qualitative analysis is performed for all kinds of energy management strategies that are used in HEVs in detail, essential characteristics involving pros and cons, interconnections and improvement potential among various energy management strategies are revealed from the view of control theory. Finally, latest developing trends in energy management strategies of HEVs are presented to improve the performance of HEVs based on above quantitative analysis and qualitative analysis, covering driving cycle recognition/prediction algorithms, integrated multi-objective, coordinated optimization energy management strategies, good balance between computation complexity and optimization performance of energy management strategies, fair and credible evaluation system of energy management strategies. This paper not only first provides a comprehensive analysis of energy management strategies for HEVs, but also puts forward the emphasis and orientation of future study, which will broaden relevant researchers' vision and promote the development of a simple and practical energy management controller with low cost and high performance for HEVs. (C) 2015 Elsevier Ltd. All rights reserved.