Study On Control Strategies Of Regenerative Braking System For HEV Bus Based On ABS

Because the environmental protection measures are more and more stringent in the world, the scenarios of substituting fuel engine vehicles become more and more. But the mode which is the most practical value and has been in commercial operation is only Hybrid Electric Vehicle. Compared with the conventional vehicle, Hybrid Electric Vehicle can not only optimize the work range of the engine, but also convert the kinetic energy, which is converted to heat energy in the conventional vehicle, to electric energy and stores it in the battery when the vehicle is decelerating or braking to stop. This is one of the reasons why Hybrid Electric Vehicle is more energy efficient.There are two important issues in the design process of regenerative braking system. First, how to distribute the total braking forces on the front axle and rear axle in order to minimize the stopping distance and keep the vehicle stability; second, how to distribute the total braking forces required between the regenerative brake force and the mechanical brake force of the driving axle in order to regenerate the kinetic energy as much as possible.In this paper, the meaning and the principle of the regenerative braking in HEV are discusses first, and the design requirements of the regenerative braking system are explored. Then the paper collects the development status of the study on the regenerative braking at home and abroad now, and some simple control strategies of the regenerative braking are introduced.This paper takes a dual-axis parallel hybrid electric bus as the research object. In chapter two, the fundamental structure and the layout scheme of the dynamic assemble, the parameters of the vehicle and assembles, the fundamental structure of the regenerative braking system is introduced briefly first; then the paper carries out the force analysis when the vehicle is braking to determine the mechanical braking force distribution on the front axle and rear axle; then based on the requirements of the braking regulations by ECER13, the range of the braking force distribution coefficient is determined.In chapter three, three common control strategies of the regenerative braking system are introduced; then according to the characteristics of the braking system in this bus, a control strategy of Regenerative Braking System which is adapt to hybrid electric bus is designed in the paper. This strategy consists of two parts, the total braking force distribution on the front axle and rear axle and the rear braking force distribution between the regenerative brake force and the mechanical brake force of the driving axle. On the basis of different braking force, the braking force distribution on the front axle and rear axle is changed; but in the aspect of rear braking force distribution, the motor braking force is prior to using, and the valves of ABS, TCS are used to adjust air pressure. Afterwards, based on the restrictions of the braking regulations by ECER13, the rationality of the braking force distribution coefficient range that calculated above .The control strategy raised in this paper just makes a little change to the original braking system, and can not only achieve the objective of recovering energy,but also keep the stability during braking.At last, the author builds the braking system model of HEV using the MATLAB/SIMULINK software, adds the control strategy raised in the paper into the model and validates the control effect and feasibility of the strategy; modifies braking control strategy of the dual.axis parallel HEV model in ADVISOR, simulates a number of driving cycles and compares the results with the control strategy in ADVISOR, which validates the effect of energy recovering. The simulation results indicate that the control strategy raised in the paper can improve the fuel economy of the vehicle.