Study On Mode-switch Of Hybrid Electric Vehicle Control Strategy Based On Traffic Scene

In response to the consumption of fossil energy and environmental pollution,new energy vehicles have received more and more attention.Because hybrid vehicles(HEV)have the advantages of low battery technology requirements,various types of working conditions and long cruising range,they are increasingly favored by various auto companies.HEV can be combined into two different working modes by different power sources.When different working modes are switched to each other,power transmission system will be interrupted or torque and speed will fluctuate,which will affect the driving performance and ride comfort.The mode switching of the traditional HEV is determined by acceleration/braking and current vehicle speed and battery SOC.Only when the system status changes,its mode will change according to the set "mode switching boundary condition",and the engine response is slower when switching,so traditional mode switching is "passive".With the increasing use of intelligent transportation technology in real vehicles,there is still no systematic research on the impact of road condition information on the mode switching of hybrid vehicles.By applying the intelligent transportation system,it is possible to obtain information such as the position and speed of the vehicle in advance,and consider using the traffic information acquired in advance to determine the future working mode of the hybrid system.By comparing the current mode with the next-time mode,under the premise of different conditions,active control of key components such as engine,motor,clutch to convert "passive mode switching" to "active mode switching",further improve the driving performance.In this paper,the plug-in single-axis parallel hybrid system is taken as the research object,and the active mode switching control strategy of hybrid vehicle based on traffic scene is studied.The main research contents are as follows:1)The structure analysis of the research object of this paper is carried,and the dynamic analysis of the key components is carried out,and the models of engine,ISG motor,automatic clutch and transmission are established on the Matlab/Simulink respectively.2)The working mode of the hybrid system studied in this paper is analyzed,and it is divided into the engine intervention and exit working system,and the dynamic analysis in the process of switching between the typical drive modes of the engine intervention and the exit drive system is emphasized.and the criteria and methods for evaluating the quality of the mode switching are determined.3)In order to study the initiative of hybrid system mode switching based on traffic scenarios,the upper and lower control strategies of active mode switching of hybrid vehicles based on traffic scenarios are formulated,mainly includes:(1)Firstly,in order to meet the possibility that the hybrid system has mode switching in a certain traffic scenario,the upper layer control algorithm of the Optimal Traffic Light Control(OTLC)is discussed and established.Traffic scenarios is build and solve target speeds according it.Combined with the boundary conditions of the mode switching and the determined target vehicle speed,the specific mode switching requirements of the hybrid system in the traffic scenario are determined.(2)Torque distribution is a part of the mode switching control strategy.This paper establishes a real-time optimal torque distribution algorithm aiming at the economic function.Based on the real-time optimized torque distribution algorithm,the SOC threshold and the torque distribution algorithm during hybrid drive are optimized.Then it is compared with the traditional logic gate rule torque distribution algorithm.(3)The switching between specific modes involved in the constructed traffic scene is compared with the corresponding traditional mode switching,and the dynamic analysis of the switching process is performed.Finally,the corresponding active mode switching control algorithm and control logic are formulated based on the real-time optimized torque distribution algorithm.The real-time optimized torque distribution algorithm and the active mode switching algorithm form a lower layer control strategy.4)The semi-physical real-time simulation platform is built to verify and analyze the formulated control strategy.Using the real-time simulation system of NI(National Instrument)and the VCU vehicle controller and the cockpit to form a closed-loop loop,realtime simulation verification of the active mode switching control strategy is carried out in the specific scenario built in PreScan.Compared with the traditional "passive" mode switching control strategy,the results show that the "active" mode switching control strategy formulated in this paper can actively control key components in advance,so that mode switching can be completed ahead of time,reducing the impact degree during mode switching,improved mode switching quality.