Study On Control Strategy For Electric Vehicle At Drive Condition

As energy crisis and environmental pollution get worse, the development ofelectric car is necessarily the trend of the development of car industry.At present,thedevelopment of electric vehicle is limited by some key technology and faces obstacles.The control technology is one of the key technology of electric vehicle. Theperformance of control system influences the performance index of the electric cardirectly. This subject was aided by the chongqing natural science fund project ‘electriccar transmission system matching,optimization and the research of comprehensivecontrol’, electric cars drive transmission system parameters matching research was did,the operation characteristic of driving conditions was analyzed,and control strategiesresearch at driving condition was did. The feasibility of the control strategy and vehicleperformance through the establishment of the simulation model of driving conditionshave been verified.The main research work in this paper is as follows:①The structure of electric vehicle driveline and the flow of matching design wasanalyzed. According to the requirements of vehicle performance,the performancecharacteristics of the electric motor and work characteristics of battery,transmissionsystem parameters on the effect of vehicle performance was considered.The parametersof drive motor, battery packs and transmission were matched. Fanaly the validmatching design method was obtained.During the matching progress,the selectingmethod of peak power,maximum speed and the influence of the extensive constantpower coefficient to the power transmission system parameters matching wereresearched with some emphasis.②The structure of vehicle control system, the function and tasks of pure electricvehicle control system,which needed to execute in actual driving were analyzed.According to the control system of the function definition, the vehicle driving controlstrategy, the shift control strategies based on the economical efficiency and controlstrategy considering the impact of attachment energy comsumption were established.③Under the precondition of both the dynamic performance and fuel economy inthe vehicle, the operating characteristics of the electric car at driving conditions wascombined with and the method was put forward that the vehicle running state at drivingconditions was divided into four modes, the logical relationship of the four modes wasanalyzed.Taking starting, acceleration such as the typical working conditions for an example,dynamics was analyzed.and control strategy were researched according tostarting, accelerating, limp driving condition,etc. Acceleration torque compensationcontrol strategy was researched with some emphasis.Fuzzy control algorithm wasadopted to develop a driver intention indentification controller,which utilized theaccelerator pedal position and its change rate as the input,and the target incrementaltorque as the output.④In the MATLAB/Simulink software environment, the vehicle simulation modelwere established.The vehcle simulation model consisted of driver module, the vehiclecontroller module, motor module, battery module, the transmission module, etc. Basedon the proposed control strategy and established simulation model, the electric vehicleperformance was tested,meanwhile the simulation,analysis and comparison was did atstarting, acceleration, climbing, limping testing conditon.