Graph Modeling And Scheme Design Of Dual Planetary Gear EVT Hybrid System

Energy and environmental issues have greatly promoted the emergence of new energy vehicles and the development of new energy technologies.At present,the thermal efficiency of traditional internal combustion engine car is low,and the exhaust pollution is serious.For the pure electric vehicles,on behalf of direction of the future,there are many obstacles in the existing technology,for example,the driving range is short,the cost is too high,and the infrastructure is not perfect.As a solution of transitional period,the hybrid electric vehicle(HEV)with low emission and high driving range is the most promising energy-saving and environmental solution.The transmission system and powertrain of HEV,as the most critical technology,has become the focus and difficulty of the present research.The EVT hybrid transmission technology with planetary gear mechanism has received widespread attention and related patents are countless.In this paper,based on the mathematical method of Graph Theory,taking the dual planetary EVT hybrid transmission system as the object of study,the following researches are conducted.On the basis of the existing layered drawing model of EVT hybrid transmission system,the connections between the power sources and the dual planetary gear mechanism are further considered,combining with the characteristics of the multi-power source and the multi-mode of the hybrid powertrain,the improved graphic model of EVT system is put forward.Based on this,the mathematic model of the dual planetary EVT hybrid transmission system--the adjacency matrix is introduced,by which the mechanism is transformed into computer codes,which lays the foundation for the computer-aided analysis and design of mechanism.On the basis of the adjacency matrix,the methods of configuration synthesis and scheme design of the dual planetary EVT hybrid transmission system are proposed.By extracting the "Binary Sequence" in the adjacency matrix which containing all the core information of the transmission,combined with the "Complete Graph" theory,all possible 0/1 transforms are traversed to obtain all possible transmission configurations,and the basic configuration pool of the dual planetary EVT hybrid transmission system is set up.Furtherly,feasibility screening and isomorphism elimination of the configuration pool are conducted,and the final complete and reasonable configuration pool is set up,and the method of combining configurations by switching clutches to generate transmission scheme is proposed.Based on “Basic Circuit” method and the mechanical analysis of the independent components of the planetary mechanism,the kinematics/dynamics analysis of the dual planetary EVT hybrid transmission system is carried out.The initial kinematics and dynamics matrix A0,which is common to all dual planetary EVT hybrid transmission systems,is proposed to automate the kinematics/dynamics analysis of all configurations in the configuration library through the initial transformation of matrix,and the 5# transmission scheme is taken as an example to validate the validity and applicability of the automatic modeling and analysis method.Based on “Dynamic Programming” algorithm,the economic simulation and parameter optimization of the dual planetary EVT hybrid transmission system are carried out.Prius,the 5# transmission scheme and transmission based on Ravigneaux planetary gear train are compared to analysis their economic differences in fuel consumption and to verify the feasibility of the dual planetary EVT hybrid transmission system.In this paper,modeling,analysis,scheme design,simulation and parameter optimization of the dual planetary EVT hybrid transmission system provide a reference for the transmission and powertrain design of HEV.