Instantaneous Optimal Control Strategy Based On A Variable Equivalent Factor For A Parallel Hybrid Electric Vehicle

At present,the research on Equivalent Consumption Minimization Strategy(ECMS)of the instantaneous optimization control strategy in Hybrid electric vehicle focuses on the study of ECMS based on a constant equivalent factor,but the strategy has poor calculation accuracy and poor adaptability to the complex and unknown driving cycle.Therefore,researching the instantaneous optimization control strategy based on a variable equivalence factor has important actual reference value for improving the vehicle fuel economy and adaptability to driving cycles.Firstly,On the basis of analyzing the structural characteristics of the PHEV,the mathematical model of each component and vehicle dynamics model are established.After analyzing the energy flow in different working modes,the simulation model of the whole vehicle is established with system modeling.And starting from the general problem of energy management,the concept of equivalent fuel consumption is introduced,which is combined with the instantaneous optimization theory,an optimization objective function of control strategy is constructed and an instantaneous optimization model based on ECMS is constructed.It provides the basis for the instantaneous optimization control strategy based on a variable factor.Secondly,an instantaneous optimization control strategy based on a variable equivalent factor is designed.Under the condition that the driving cycle is known,an ECMS based on a constant equivalent factor is designed.Through the control performance analysis,the improvement of the control algorithm is confirmed.Considering the relationship of the equivalent factor and real-time driving cycle,the state of charge(SOC)is added to calculate the variable equivalent factor,the value related to the real-time operating conditions are obtained,which improves the adaptability to driving cycles.Thirdly,in order to further enhance the adaptability of driving cycles,an instantaneous optimization control strategy based on driving cycle recognition is designed.According to the cluster analysis,the driving conditions are divided into four types,and the optimal equivalent factor of each representative cycle is determined.For a section of driving cycle,the driving cycle type is obtained through the driving cycle recognition,the corresponding optimal equivalent factor is selected,and the equivalent factor is adjusted according to the SOC of the battery,so that the instantaneous optimal control can be carried out.Finally,the simulation of the control strategies is carried out.The simulation results show that both the instantaneous optimization control strategy based on variable factor and the instantaneous optimization control strategy based on driving cycle recognition can both improve the fuel economy of the vehicle to a certain extent,improve the efficiency of the engine and enhance the adaptability for driving cycles.