Regenerative Braking Research Of Pure Electric Vehicle

Regenerative braking is one of important functions of pure electric vehicle, which can not only ensure the prerequisite of braking performance but also realize the recycle of braking energy. Moreover, regenerative braking can reduce energy consumption, extend driving range as well as reduce the abrasion of the friction disk.In order to ensure the prerequisite of braking safety and recycle more energy, it is necessary to work out an appropriate control strategy. This paper focus on Chang An mini pure electric vehicle, based on the analysis of braking system structure, bring up the parallel connection regenerative braking control strategy. Establish the regenerative braking model and carry out the simulation analysis as well as improve the control strategy which brought up before based on the simulation results. The main research work in this paper is as follows:â‘ Analyze the braking system structure of the pure electric vehicle, based on the requirements of braking performance, considering the influence of motor working character, battery working character as well as ECE rule to regenerative braking. The braking force distribution coefficient which satisfy the ECE braking rule is worked out, The limitations of motor maximum torque and battery charging power which provide theoretical basis for the institution of regenerative braking control strategy is calculated.â‘¡Based on the analysis of braking intensity distribution of many driving conditions, work out parallel connection regenerative braking control strategy. More over, in order to make the variation of motor braking force gently and optimize the feeling of the driver, bring in the impact factors of velocity and battery SOC when deciding the practical motor braking force. Obtain the optimal working line of motor and battery and work out the shifting control strategy of regenerative braking.â‘¢Based on the theory of vehicle dynamic, establish the simulation model of electric vehicle regenerative braking system which includes vehicle dynamic model, transmission model, motor model, battery model as well as control strategy model. In order to compare different regenerative braking control strategies, the simulation model integrate many control strategies which provide a necessary platform for verifying the validity of the strategies.â‘£Analyze the parallel connection regenerative braking control strategy using normal braking and typical city driving cycle and improve the parallel connection regenerative braking control strategy based on the simulation results as well as bring up two improving programs. Compare the influence of the fixed-gear program and two-speed program on regenerative braking energy.