Modification of Equivalent Consumption Minimization Strategy for a Hybrid Electric Vehicle

Equivalent consumption minimization strategy (ECMS) is one of the main real-time control strategies for hybrid electric vehicles (HEVs). This paper proposes a method to modify this strategy. This modification reduces calculation time of ECMS and therefore, facilitates its application as the real-time controller. Dynamic programming (DP) method is employed to reach this aim. This method is applied on the considered HEV in different drive cycles and its results are used to reduce the calculation time of the ECMS. It is notable that the objective of DP in the urban cycles is to simultaneously minimize the fuel consumption (FC) and NOx emission, while the objective in the highway cycles is only the vehicle FC. In order to examine the success of the proposed modifications, the modified ECMS is compared with the basic ECMS in different drive cycles. It is demonstrated that the execution time of the modified ECMS is much less than that of basic ECMS, while the vehicle's FC and NOx levels slightly increase through application of the modified ECMS.