Research On Control Strategy Of Automobile Braking Energy Recovery System

With the intensification of the oil crisis and the increasing awareness of environmental protection,the energy saving and environmental protection performance of the vehicle is highly valued by the society.However,the further development of new energy vehicles is mainly restricted by its short mileage,and the braking energy recovery system is one of the key technologies to extend the mileage and improve energy use efficiency.Therefore,under the premise of the braking safety,considering the function of driver braking intensity judgment,the braking force distribution strategy of the composite braking system is put forward for the front-drive vehicle.Then the braking energy recovery system model is built,through co-simulation proves that the system can improve the efficiency of braking energy recovery.The main contents of this paper are summarized as follows:(1)The dynamic characteristics of automobile braking are studied.Based on the analysis of the relationship between the wheel slip ratio and the braking force coefficient,the range of the slip ratio is obtained to ensure the longitudinal and lateral stability of vehicle braking.Through analyzing the process and the principle of the braking energy recovery system,provide a theoretical basis for the research of braking energy recovery.(2)The strategies of ideal braking force distribution,the optimal energy recovery and parallel energy recovery and the advantages and disadvantages of the three methods are analyzed.After considering ECE regulation,the motor peak torque,battery charge performance as the main restrictive conditions and combining them with driver braking intensity discrimination characteristics,a new control strategy of regenerative braking force distribution is proposed for the vehicle.(3)The vehicle dynamic model,the permanent magnet brushless DC motor model,battery model and the braking force distribution strategy model which is combining the ABS system are built.In order to ensure the exit ride comfort of motor regenerative braking,the influence factors of the vehicle speed and the SOC value of the battery are considered to construct the braking energy recovery system,and the co-simulation of the system is carried out.(4)Four evaluation indexes are defined to evaluate the performance of the braking energy recovery system.In the typical braking condition,through the simulation of braking performance and energy recovery characteristics of the vehicle,the effectiveness of the composite braking system braking force distribution strategy is studied and compared to the ideal braking force distribution strategy in the medium braking intensity.