Research On Parameters Optimization And Control Strategy Of Parallel Hydraulic Hybrid Vehicle

With the increase of global car ownership,the energy crisis and environmental pollution caused by fossil fuel consumption of vehicles have gradually aroused people's attention.As one of the technology of vehicle energy saving and emission reduction,the hydraulic hybrid power technology has become a hot spot of research in automobile manufacturers and scientific research institutions all over the world.Because of its high power density,high energy conversion efficiency,safety and cleanliness and low cost,hydraulic hybrid power system has good application prospects in the field of construction vehicle.The cooperation projects the research topic of this paper comes from the MCC Baosteel.The content of the research is modifying Shanqi Delong M3000 dumpers in the Baosteel plant with hydraulic hybrid power system which are working in low speed and heavy load,frequent start and stop state,to achieve the purpose of energy saving.This paper mainly studies the following aspects:(1)Design of the HHV(hydraulic hybrid vehicle)Configuration and SystemThis paper studies the advantages and disadvantages of different configurations of hydraulic hybrid power system,and determines the configuration method suitable for the research of this subject-post parallel hydraulic hybrid power system.For the problem of the self-priming capacity of HPM(hydraulic pump motor),we have designed a scheme that using gear pump to provide pressure oil directly for the HPM so that the low pressure accumulator could be eliminated,the effective working pressure could be improve and the volume and weight of the system could be reduced.In the hydraulic hybrid power system,the electromagnetic clutch is used to control the gear pump,which solves the overflow loss when the gear pump displacement does not match with the HPM displacement.At the same time,the protection design is added to the oil circuit to prevent the HPM from being damaged by suction.(2)Establishing the Mathematical Model and Parameter Optimization of the Whole VehicleThe characteristics of hydraulic hybrid vehicle are analyzed,and the mathematical model of hydraulic hybrid vehicle is established,including driver model,engine model,accumulator model,HPM model,vehicle model and so on.Based on the mathematical model,a multi-objective optimization function based on the comprehensive performance of the vehicle is established,and the multi-objective optimization problem is transformed into a single objective optimization problem by weighting method.This paper proposes parallel hydraulic hybrid system parameter optimization method based on genetic algorithm to determine the parameter of system,including high pressure accumulator volume and its maximum working pressure and minimum working pressure and the maximum displacement of HPM.(3)Design of the Energy Management Strategy and Simulation Research Based on the Logic ThresholdAiming at Weichai WP10.300E40 diesel engine equipped in M3000,the characteristics of the engine is analyzed,and the energy management strategy based on the logic threshold is designed,meanwhile the parameters of the energy management strategy is determined.Based on the AMESim platform,the hydraulic hybrid vehicle simulation model and the traditional vehicle model are established.in order to make the simulation model close to the actual situation,according to the real road test data of Baosteel,the cycle condition of Baosteel is designed.The fuel consumption,power performance and braking performance of hydraulic hybrid vehicle and traditional vehicle under different load conditions were simulated and analyzed.The causes of the error between simulation results and experimental results were compared and analyzed.The simulation results show that the fuel consumption of the HHV is decreased by 35.5%,the dynamic performance is increased by 15.5%and the braking performance is improved by 40.9%.(4)HHV Prototype Development and Experiment ResearchBased on the designed hydraulic hybrid power system scheme and control strategy,the prototype vehicle is developed and the design control strategy is applied to the prototype.Some experiments were carried out on the prototype,including energy efficiency experiment,dynamic performance experiment and oil saving efficiency experiment.Through experiments,the performance of HHV under different working conditions are analyzed.The experimental results show that the average oil consumption of the HHV is decreased by 36.8%and the dynamic performance is increased by 16.2%.