Research On Control Strategy Of Hybrid Electric Vehicle Based On Equivalent Fuel Consumption

Against the background of current automotive exhaust pollution,shortage of petroleum resources and energy security,plug-in hybrid electric vehicles(PHEV)provides an effective way to solve the problem.In order to make the energy management strategy can effectively improve the emission performance and fuel economy performance of the vehicle,aiming at the problem of that constant equivalent fuel factor is difficult to optimize online,the influence of mileage and initial state of charge on equivalent fuel factor is not considered,etc.Take PHEV with coaxial parallel P2 configuration as the research object,aiming to optimize energy distribution and improve fuel economy,and enable the car to fully utilize battery power,carried out the design study of the whole vehicle energy management strategy and hardware-in-the-loop real-time simulation test.Analyzed the composition of each component,the corresponding mathematical model was developed based on the kinetic properties,and based on the MATLAB/Simulink software,the simulation models of various components including the engine,motor,power battery,vehicle body,transmission system and driver are established.According to design principles and layered architecture,designed a strategy based on optimal engine output torque and motor assist rules,divided the working range of the power battery,developed constraints for vehicle operating mode,this make the engine work in the high efficiency area,achieved reasonable energy and torque distribution,then the rationality of the control strategy is verified by simulation under two cyclic conditions.The combined 100 km fuel consumption under ideal conditions and the pollutant emissions under NEDC conditions were calculated.Developed an instantaneous optimization energy management strategy based on the ECMS algorithm,made an analysis of the instantaneous optimization theory,and established a mathematical optimization model with the equivalent fuel consumption rate and controlled energy distribution as the goal,converted into Hamilton function of PHEV based on Pontryagin minimum principle,taking SOC of power battery as state variable and taking engine or motor torque as control variable,solved optimal control sequences using ECMS algorithm,compared with the rule-based strategy,the vehicle fuel economy is improved by 5.42%.The interaction between the equivalent fuel factor and the initial SOC and driving distance of the battery is further investigated through simulation experiments,designed the trajectory reference following strategy for SOC,Enabled plug-in hybrid electric vehicles to make full use of electrical energy in real driving.Completed hardware-in-the-loop simulation experiments based on d SPACE devices,established the rapid control prototype and real-time simulation system,using RTI realtime interface configuration to complete vehicle model and control model,and the model was compiled using the host computer environment and automatic code generation technology,then download to the rack system and controller through Control Desk.Established CAN communication protocol and completed the hardware-in-the-loop realtime interaction,monitoring and recording data,analyze the experimental results.Results show that dynamics follow well,the feasibility and real-time performance of vehicle energy management strategy were verified,there is low error in battery SOC,the maximum error is 1.06%,following the trend of change is consistent,the energy of the battery can be used reasonably and fully,verified the effectiveness of vehicle energy management strategy,the engine can operate in a high efficiency zone,this can improve fuel economy to a certain extent.