Research On Braking Energy Recovery Control Strategy Of Electric Vehicles Considering Battery Lif

In recent years,with the large-scale popularization of automobiles and the rising price of oil,the problems of environmental pollution and energy security have been plaguing governments of various countries.Electric vehicles do not use oil and do not emit any toxic and harmful gases,which can effectively alleviate environmental and energy problems.However,due to the constraints of battery technology,the problem of short cruising range of electric vehicles cannot be solved.Braking energy recovery technology can effectively make up for this defect and effectively improve the mileage of the car.In the past,most experts and scholars focused on improving the efficiency of braking energy recovery,ignoring the impact of braking energy recovery on battery life.In this thesis,a braking energy recovery strategy that can ensure a certain energy recovery rate and prolong battery life will be proposed.The main research contents of this paper are as follows:(1)The basic structure and working principle of the electric vehicle braking system are introduced,and the factors affecting the braking energy recovery of pure electric vehicles and three braking modes are analyzed.(2)The vehicle driving dynamics and braking process dynamics are analyzed,and the braking force distribution range is divided on the basis of ECE regulations and ideal braking curve.(3)When the SOC of the power battery is at different levels,the degree of damage to the electrode material caused by the charging current is also different,which in turn affects the service life of the battery.According to the different SOC of the power battery,there are corresponding differences in the impedance spectrum rate.Considering the influence of the braking force distribution on the charging current in the typical working conditions of vehicle braking energy recovery,the power battery SOC is divided into three intervals [0,0.1],(0.1,0.9),and [0.9,1].(4)Based on the division of the SOC interval of the power battery,a braking energy recovery control strategy considering the battery life is formulated.According to the change of the SOC of the power battery,a corresponding braking force distribution scheme is adopted to ensure the braking intensity and braking energy.At the same time of improving the recovery rate,the impact on the service life of the battery is reduced.Based on this control strategy,a fuzzy controller for braking energy recovery is designed.(5)The system modeling and simulation verification are carried out for the braking energy recovery strategy and its fuzzy controller that consider battery life,and the simulation results are compared with the mainstream control strategies.The analysis results show that the control strategy formulated in this thesis is On the premise of ensuring a high braking energy recovery rate,the service life of the power battery can be effectively extended by 6.17%,which verifies the effectiveness of the braking energy recovery strategy considering the battery life and the feasibility of the fuzzy controller.