Mode Switching And Coordinating Control Strategy Of New Electromechanical Coupling System For PHEV

China takes pure electric vehicles,plug-in hybrid electric vehicles and fuel cell vehicles as the "three vertical" research and development layout,which is the automobile industry planning strategy in the 14th five-year Plan,in which electromechanical coupling and low carbonization are the development focus of energy-saving vehicles.Plug-in hybrid electric vehicle(PHEV)solves the problem of pure electric drive "range anxiety" and can give consideration to high efficiency and energy saving.However,PHEV multi-energy power system integration is a key technology that needs to be solved urgently.Especially PHEV,which is represented by the integrated dual-motor multi-mode powertrain,has brought about many problems such as complex energy management strategies and frequent mode switching while improving economy and power.How to choose a suitable switching strategy and control method is of great significance to suppress the torque fluctuation and longitudinal impact of the whole vehicle,and then improve the ride comfort and comfort of the vehicle.Based on the National Key R&D Program "New Energy Vehicle Special Project",this paper launches the research on the mode switching coordinated control of a new dual-motor hybrid coupled PHEV.The main research includes:Firstly,the dynamic coupling mechanism of the new dual motor coupling mechanism is analyzed,and the parameters of each part of the system are clarified.The engine,motor,clutch,transmission system and other key components as well as the vehicle longitudinal dynamics simulation model are established.The feasible working mode of the system,the working state of each component under each mode,the energy transfer path and the state equation of the system are analyzed to provide a basis for the further design of the mode switching coordination control strategy.Secondly,the process of switching from pure electric drive to engine drive mode involving the action of a single clutch is selected as the research object.This process is divided into pure electric drive,engine starting,clutch engagement,torque compensation,and separate engine drive stages,and analyze the work of each stage Characteristic,proposed a mode switching optimization control strategy based on fuzzy control algorithm.The simulation results show that the maximum impact of the whole vehicle is reduced by 73.5%during the switching process,and the vehicle ride comfort is improved.The switching process from dual-motor pure electric drive to “dual-motor + engine”hybrid drive involving multiple clutch actions is further selected as the research object.After analyzing the working sequence of the clutch,it is obtained that the first clutch C2,the simultaneous engagement of the clutches C1 and C3 are adopted as the best clutch combination sequence.The comprehensive and coordinated control of the clutch engagement and disengagement process shortens the switching time while reducing the impact of the vehicle by 79.9%,effectively improving the vehicle ride comfort during the switching process.Finally,a hardware-in-the-loop simulation test platform was built,and the mode switching coordinated control strategy formulated in this paper was tested in Hi L.The test verification results showed that the coordinated control strategy and offline simulation proposed in this paper for single clutch and multiple clutch control respectively.The results show consistent trends,which verified the effectiveness and practicability of the control strategy.