Research On PHEV Control Strategy Based On UKF Observer Of The Aftertreatment System

Resource shortage and environment pollution are big challenges in the world.Plug-in Hybrid Electric Vehicle(PHEV),due to it's low fuel consumption,low emissions,and unlimited driving range,which can combine the advantage of electric vehicle and conventional internal combustion engine vehicle,becomes research spot recently as a new type of vehicle is considered as an effective way to solve such problems.Energy management strategy is the key technique of hybrid electric vehicle control system.Different operating conditions use different working modes to optimize the fuel consumption and emissions of the vehicle to be more optimized than traditional vehicles.In this paper,a hybrid diesel-fueled PHEV is used as the research object to study the design of vehicle simulation,temperature observation and control strategy.The theoretical and experimental modeling methods were used to study the fuel economy performance and emission performance of PHEV.The main work of the thesis is as follows:(1)Under the MATLAB/Simulink simulation platform,based on the structural characteristics and working characteristics of the P2 type PHEV,the engine model,the motor model,the battery model,the drive train model,and the longitudinal dynamics model of the vehicle are constructed by theoretical modeling and experimental modeling.According to the internal heat balance principle of the post-treatment system,the mean value model of DOC,DPF and SCR temperature is built,and the chemical reaction model is constructed according to the chemical reaction principle of DOC and SCR in the aftertreatment system.(2)Based on the aftertreatment system temperature mean value model,its EKF and UKF observers were established.Using the test bench to develop the experimental scheme,importing the temperature data of DOC inlet,DPF inlet and outlet,and SCR outlet are finally obtained.The established mean value model is verified and calibrated by least squares method,and DOC,DPF and SCR temperature observations are established by using EKF and UKF algorithms.The experimental data was used to verify the effectiveness of the observer.(3)The control strategies of the PHEV have been developed.analyzing the characteristics of power flow in different working modes of P2 type PHEV.The rule control strategy combining charge-depleting mode and charge-sustain mode is proposed.Then,the switching conditions between modes are established according to the energy conversion relationship between components in PHEV.Under the specific conditions,with the minimum fuel consumption and emission as the optimization goal,the control strategy of minimum fuel consumption and equivalent fuel consumption(ECMS)with battery SOC and SCR outlet temperature as state variables is proposed and simulated.The simulation results show that the fuel consumption and emissions of the ECMS strategy are significantly lower than those of the rule-based control strategy under the premise of satisfying the dynamic and control effects.(4)In the dSPACE/Autobox platform,the hardware-in-the-loop simulation environment of the control strategy is built and the hardware-in-the-loop experiment is completed.The ECMS control strategy proposed in this paper is verified.The experimental results show that the proposed control strategy can greatly improve the fuel economy performance and emission performance of PHEV.The hardware-in-the-loop test also verifies the correctness of the model...