| Hybrid electric vehicle effectively combines the advantages of internal combustion engine vehicle and electric vehicle and takes advantage of regenerative braking and energy management,so as to ensure the power performance,safety and fuel economy.The braking control and energy management of hybrid electric vehicle(HEV)is a complex problem of nonlinear time-varying system,which involves the uncertainty of road surface and energy cooperative control among multiple power sources.This dissertation investigates the braking control and energy management of hybrid electric vehicle and the innovative results are achieved as follows:(1)Considering the characteristics of fast response and braking energy recovery of the motor in hybrid electric vehicle,the braking control and distribution of hybrid electric vehicle based on slip ratio are studied.For the uncertainty and modeling error of the system,the model reference adaptive control and fuzzy logic control strategies are designed to control and distribute the braking force through feedback road conditions and the performance of braking control and robustness and regenerative braking efficiency are improved.(2)The braking force control based on road observer and the braking force distribution based on SOC are researched.A double-layer braking control structure is adopted to study the braking control and energy recovery.In the braking control layer,a braking force control method based on the road disturbance observer is proposed to improve the braking control strategy,which cancels the assumption that which cancels the assumption that the state change of the controlled object is zero,and uses the nonlinear observer to estimate and compensate the road uncertainty and load change.In the braking force distribution layer,a new braking torque distribution strategy based on battery SOC is proposed.Considering the state and change of battery SOC,a new braking torque distribution strategy based on battery SOC is proposed to achieve higher regenerative braking efficiency and fuel economy.(3)The tracking control and energy management of hybrid electric vehicle is studied based on the information of the vehicle in front.According to the information,a cooperative control method of tracking control and energy management of hybrid electric vehicle based on safety distance is proposed.Considering the influence of speed limit,slope and load variation on vehicle tracking,safety and energy consumption,a dynamic surface control method based on observer is designed,which not only ensures the optimization of control,but also solves the requirements of condition prediction and speed planning.Then,the receding dynamic programming algorithm is adopted in the energy management of hybrid electric vehicle within the safe distance.This method solves the problems of storage space limitation and heavy online computing burden of dynamic programming algorithm,and realizes the real-time energy management optimization of hybrid electric vehicle.(4)The platoon control and energy management of HEV vehicle are studied.A model predictive control is used for real-time energy management of the leading vehicle,and the fuel economy of the vehicle platoon is improved by tracking control.Based on the speed and acceleration information of the leading vehicle,a sliding mode controller is designed.Considering the speed tracking error with leading vehicle and vehicle spacing error,the method not only ensures the speed consistency of HEV platoon,but also avoids the collision with the front vehicle.Through the parameter selection and stability analysis of the controller,the stability of HEV platoon is ensured. |
