Research On Eco-driving Speed Optimization Of Connected PHEV At Signalized Intersection

With the increasingly serious problems of energy consumption and environmental pollution,under the guidance of fuel consumption and emission regulations,new energy vehicles have become the focus of attention of all countries.Due to the mileage anxiety of pure electric vehicles,as well as the news of rising prices of raw materials and batteries and rising oil prices,hybrid models began to develop rapidly.Plug-in hybrid electric vehicle(PHEV)is more competitive in the current transition period because it takes into account power and emission.PHEV improves the energy structure of the vehicle and improves the efficiency of energy utilization.However,in the process of vehicle movement,in addition to the body structure of PHEV,its economy is also limited by the driving behavior of the vehicle.For vehicles traveling on urban roads,when there is a signalized intersection on the road,due to the inability to predict the signal phase timing and road traffic information at the signalized intersection,vehicles often have emergency deceleration,rapid acceleration and long-term parking under the red light,resulting in the loss of vehicle energy consumption and traffic congestion.Under the background of the rapid development of vehicle road cooperative traffic technology and vehicle electrification,networking and intelligence,combined with the structural characteristics of PHEV,the development of energy-saving driving strategy based on this model on the urban signal road provides a new idea for completing the key tasks of energy conservation and emission reduction,and has great application prospects and research significance in improving the energy efficiency of vehicles.Therefore,this paper takes the connected and intelligent PHEV as the research object,and uses the road signal lamps and other relevant information obtained by the vehicle road cooperative communication technology to analyze and study the energy-saving traffic problem of PHEV signal lamp intersection.The main contents are as follows:(1)Analytical modeling and validation of PHEV.Through the correlation analysis of the advantages and disadvantages of PHEV under various configurations,it is determined to be based on P2.5 configuration of connected and intelligent PHEV as the research object of this paper.According to the structural characteristics of the PHEV with this configuration,the energy flow under each working mode is analyzed,and the whole vehicle model for the vehicle is established.Finally,the rule-based energy management strategy is adopted for the simulation calculation for the simulation model,which provides support for the traffic optimization of subsequent PHEV signalized intersection.(2)Analysis and design of energy-saving traffic optimization method at signalized intersections based on predefined strategies.On the basis of completing the established vehicle model and energy management strategy,a traffic optimization method based on predefined strategy is formulated according to the different power sources of PHEV in different power stages.Based on the driving data of vehicles on the actual urban road,the driving characteristics of vehicles passing through the signalized intersection are analyzed.According to the characteristics of vehicles driving between the two signalized intersections,the behavior of vehicles passing through this distance is processed in sections,and a predefined energy-saving traffic optimization scheme is formulated.By analyzing the constant speed and speed change process of PHEV during driving,The economic speed at constant speed and the change curve of acceleration and deceleration in the process of speed change are determined.Finally,the energy-saving traffic optimization model under the predefined strategy is established by using the idea of hierarchical control,which provides a general energy-saving method under the predefined strategy for PHEV traffic at the signalized intersection.(3)Analyze and design an energy-saving traffic optimization method at signalized intersections based on Dynamic Programming(DP)algorithm.The predefined strategy provides a general sub optimization scheme for the energy-saving traffic at the signalized intersection.In order to consider the energy-saving working characteristics of PHEV’s own energy optimization,realize the optimal allocation of PHEV’s internal energy while planning the vehicle speed at the signalized intersection,and establish a global optimization problem that cooperatively optimizes the vehicle speed planning and energy management of PHEV signalized intersection with the goal of minimizing the global energy consumption cost.Firstly,through the theoretical analysis of DP algorithm,the state variables,decision variables,index functions,state transition equations and constraints of the optimization problem are formulated,and the discrete non-standard form constraints in distance domain are transformed into standard constraints in time domain to optimize the multi constraint problem.Secondly,using the representation method based on three-dimensional state space,the realization process of reverse solution and forward optimization of optimization problem is explained.Finally,the parallel computing method under the framework of DP algorithm is designed to improve the speed of DP global optimization calculation.(4)Simulation comparison and analysis of energy-saving traffic optimization methods at signalized intersections.By formulating the evaluation index of the simulation experiment and selecting the “Accelerate-Constant-Brake(ACB)” strategy as the comparison,the simulation scenes under the distance between two signal lights and multiple signal lights are designed,and the simulation experiment is carried out with MATLAB software.At the same time,this paper compares the energy-saving potential of the PHEV signal optimization method with the road signal optimization method,and verifies the effectiveness of the energy-saving design of the PHEV signal on the road.