Research On The Integrated Optimization Control Strategy Of Plug-in Diesel-Electric Hybrid Vehicle Under Low Temperature Condition

With the intensification of the environmental pollution and the energy crisis,the automotive industry faces enormous challenges to find an optimal,cost-efficient balance between fuel efficiency and emission.Plug-in Hybrid Electric Vehicles(PHEV)can efficiently save energy and decrease the harmful emission of vehicles with a larger battery energy storage and external charging device,which have become one of the most important technical ways to achieve the vehicle energy conservation and emission reduction in China.As one of the key technologies of PHEV,the energy management strategy can optimize the distribution of power or torque of the engine and the motor,so as to realize the integrated optimization of fuel consumption and emission.Temperature,in cold environment,can affect not only the battery life,the capacity of charge and discharge,but also seriously the conversion efficiency of the after treatment system of diesel,namely selective catalytic reduction catalytic(SCR),to absorb and catalyze the nitrogen oxides.Therefore,considering the influence of temperature for the performance of the vehicle,it is more significant to research the integrated optimization control of Plug-in diesel-electric hybrid vehicle at low temperature.The dissertation takes a Plug-in diesel-electric hybrid vehicle as the object of study.Considering low temperature factors,the comprehensive optimization control strategy of the vehicle have been implemented so as to improve fuel economy and reduce NOx emissions.The main details in this paper are as follows:(1)Through the data of bench test and numerical calculation method,the model of main components for Plug-in diesel-electric hybrid vehicle power system is established into Matlab/Simulink platform,including engine,motor,battery,SCR dynamic,fuzzy logic controller driver model and vehicle dynamics model,designing and verifying the vehicle energy management strategy.(2)Considering that PHEV has Charge Depletion(CD)and Charge Sustaining(CS)mode,this paper establishes the rule logic-based threshold control strategy,and formulates the conversion rules among different control modes.Finally,the correctness of the CD-CS control strategy is verified by the simulation.(3)According to Pontryagin's minimum principle(PMP),the shortest time optimal control strategy is proposed,which uses the state of charge(SOC),battery temperatureand SCR catalytic converter temperature to serve as the three state variables.Based on those three state variables,the optimal control strategy for fuel consumption and emission of Plug-in diesel-electric hybrid vehicle including the engine's start/stop optimization is applied to reduce fuel consumption and NOx emissions.Simulation analysis for the optimal control strategy established under low temperature conditions,the results show that those strategies can effectively reduce fuel consumption and emission.(4)On the basis of the dSPACE real-time simulation system,this paper establishes the rapid control prototype test of Plug-in diesel-electric hybrid power system,and the Control Desk have been utilized to implement the visual monitoring interface,which achieves data testing and control in the process of testing.The test of the motor driving alone,combined driving and driving with battery charged for Plug-in diesel-electric hybrid power transmission system is completed.The experiment results show that the energy management strategy is effective.