Research On Speed Planning Of Pure Electric Vehicle Considering Braking Energy Recovery

Pure electric vehicles have become the medium and long-term development goals of most countries due to their remarkable features such as energy saving and environmental protection.However,the main factors such as insufficient cruising range and short battery life also restrict the development of pure electric vehicles.At present,if the vehicle can optimize the driving speed curve of the self-driving pure electric vehicle during the driving process,the energy consumption problem of the whole vehicle can be effectively solved.As a key technology in the speed planning of pure electric vehicles,the control of the driving and braking energy recovery system undertakes the torque output management of the entire system.In this paper,based on the control of driving and braking torque,and the goal of the lowest energy consumption during the whole vehicle driving process,combined with road information,the speed curve of the self-driving pure electric vehicle is optimized,and the algorithm is verified.The main work of the full text is as follows:(1)Build the model of the key parts of the power system of the pure electric vehicle;introduce the performance parameters of the pure electric vehicle in this paper;select the drive motor type,build the motor numerical model,and draw the corresponding motor efficiency MAP map;select the power battery type,build the power battery external characteristic model and Battery efficiency characteristic model and establishment of power consumption evaluation index.(2)According to the longitudinal dynamics of pure electric vehicles,taking the economical and dynamic curves of the vehicle driving process as critical conditions,introduce and calculate the vehicle power-economical demand coefficient,design the driving torque control strategy of pure electric vehicles,and realize the control of the driving torque of pure electric vehicles.The control of the torque required by the drive motor,and the simulation verification is carried out to provide a reasonable drive control strategy for the economical speed planning.(3)Explain the basic principle of the braking system,analyze the energy flow of the braking energy recovery system,compare the traditional braking energy recovery control strategy,and propose the front and rear axle braking force distribution strategy in this paper;The electric motor braking power distribution strategy is developed,and the evaluation index of braking energy recovery efficiency is formulated.And carry out simulation verification to provide a reasonable braking system control strategy for economical vehicle planning.(4)The influencing factors of economic speed planning are analyzed,and the energy consumption calculation model of economic speed planning is established.The economical speed planning method for pure electric vehicles is expounded,and a speed planning algorithm based on the dynamic programming principle is designed considering factors such as the remaining charge of the battery,the torque of the drive motor,and the efficiency of braking energy recovery.Further take the road gradient and speed limit as constraints,consider the vehicle driving efficiency and vehicle energy consumption,and calculate the optimal vehicle speed curve for vehicle economy;The results show that the speed curve planned in this paper conforms to the road characteristics,which reduces the energy consumption of the whole vehicle to a certain extent and improves the energy recovery efficiency.