Research On Observer-based Energy Management Strategy Optimization For Hybrid Electric Vehicle

In the Hybrid electric vehicle,when determining the structure of the hybrid system,the driving smoothness and fuel economy of the hybrid electric vehicle are mainly determined by the energy management strategy.The optimal tracking and control based on the observer is designed for the hybrid electric system energy management strategy,which improves driving smoothness and reducing fuel consumption.The main research contents are shown as follow.Firstly,the clutch engagement process is used as the control object to control the driving smoothness by analyzing the impact of changes in the engine output torque on the energy management strategy during the clutch engagement of the hybrid system.The performance index function of the engine output torque is established and the optimal control law based on the Pontryagin’s Minimum Principle optimization algorithm is determined.Considering the stability and robustness of the time-based minima optimization algorithm are poor,the state feedback observer is designed to realize the observation estimation of the optimal control law of the original system and improve the proposed optimization algorithm.Secondly,the powertrain system is considered as the control object to optimize the driving smoothness of the transmission system,discussing the effect on energy management strategy of the hybrid electric vehicle transmission system when input torque changes,optimal control is achieved by the Pontryagin’s Minimum Principle.In order to realize the closed loop feedback process of the system based on the optimization algorithm control,and improve system control accuracy,a state feedback observer is designed for the reconstruction system.The estimate of the optimal control law for the reconstructed system and the original system is obtained when the main system can be asymptotically tracked.Finally,considering the effect of the state of charge of battery pack on fuel consumption,the non-fragile observer is used to achieve optimal tracking and control for the fuel consumption rate of the hybrid system.Taking into account the characteristics ofchanges in the speed of hybrid vehicles under certain driving conditions,a performance index function is established based on the vehicle speed,battery pack SOC and engine/motor output power,and the numerical solution to the optimal control law of hybrid system is determined by solving the Riccati equation with linear quadratic optimization algorithms.At the same time,the non-fragile observer is designed based on the H?control theory,and which is asymptotically tracked from the slave system to the main system in the presence of external interference.