Research On The Control Of Braking Energy Recovery System For Hybnd Vehicle

In recent years, with the ownership of vehicles increasing year by year, environmentand energy issues continue to accelerate, therefore the development of new energy vehicleshas become a hot research topic among the automobile manufacturers, so hybrid vehicleswith energy recovery system has come into people’s spotlight.The energy recovery system is a key part of the hybrid vehicles, in the braking processof vehicles, this system converts part of the kinetic energy through the motor into the electricenergy, and then stores the electric energy in the energy storage device, when the vehiclestarts or accelerates, the electric energy can be released by the motor to provide all or part ofthe tractive force for the vehicle, it not only improves vehicle’s fuel economy, but alsoreduces environmental pollution. At present, the braking force of most hybrid vehicles isprovided by both the motor and the mechanical braking, in the process of braking, how tocontrol the motor braking force and front-rear mechanical braking force to work in the idealdistribution, and at the same time maximize energy recovery, are the key part of presentresearch for the energy recovery system. The detailed research content of this paper based onthe distribution of braking force is as follows:Firstly, this paper introduces the background and significance of hybrid vehicles, thenoutlines the components of the energy recovery system, and analyses the force situation ofhybrid vehicles under braking, and then draws an ideal braking force distribution curve ofthe front and rear wheels, after that, studies the working principle and the specific recyclingprocess of the energy recovery system.Secondly, based on the analysis of the maximum energy recovery and the fixedpercentage braking force distribution strategy, the control logic of the energy recoverysystem and the braking force distribution strategy are designed. On the basis of complyingwith the ECE braking regulations, the braking strength from small to large is divided intofour grades, and the mathematical model of the braking force distribution control strategy isbuilt, after that the energy recovery system model of the whole vehicle is established.In order to control the deviation between the actual braking torque and ideal brakingtorque of the motor, and make the vehicle steady braking, this paper builds a motor brakingtorque PID controller, in the initial velocity30km/h,60km/h and100km/h three typicalconditions, the simulation and verification are did. The results show that the energy recoveryefficiency of the model is among14%~25%, which achieve the preliminary design goal ofthis article’s braking force control strategy.Finally, this paper designs a PID controller model based on the BP neural networkalgorithm, the model uses the self-learning ability of the BP neural network to adjust the weights, achieves the optimization of the PID control parameters. The simulation resultsshow that, the braking force distribution model with BP neural network PID controllerincreases by an average of4percentages in energy recovery efficiency than the model withconventional PID controller, the front wheel slip ratio is more stable, what’s more, the motortorque fluctuations of the conventional PID controller during the start of braking is solved,and the desired results are achieved.The research results of this paper verify the practicality and feasibility of the brakingforce distribution strategy, and will provide a certain reference value for the future’simprovement of the hybrid vehicles’braking energy recovery system.