Study On Driving Shifting Strategy Of HEV Equipped With Electric-Mechanical CVT

This paper relies on National Natural Science Foundation of China,by taking uni-axial parallel hybrid power system equipped with electric-mechanical continuously variable transmission as the research object,it researched on the working condition of hybrid system driver CVT speed control strategy,economic performance and small attachment coefficient to accelerate dynamic properties.the main research works have the following several aspects:Firstly,it analyzed structural characteristic of uni-axial parallel hybrid power system and dynamic characteristic of transmission system main parts,respectively established engine?ISG motor? electric-mechanical continuously variable transmission and other key parts models.And it gave evaluation index of dynamic and economy in hybrid electronic vehicleSecondly,it analyzed the energy management for hybrid power system and drive mode of operating mode switching.The best operation condition is separately determined in the mode of pure motor drive,motor drive,hybrid drive and driving with charging drive.The power in every drive condition was allocated base on the equivalent fuel consumption and the working efficiency of the power supply for the premise.Thus energy management strategy which based on logic threshold method is established.Then the best economic performance and dynamic performance of CVT speed ratio in the working condition of each drive was respectively calculate under the condition of energy management strategy and the running characteristics of PHEV in the small road adhesion coefficient are analyzed,and corresponding CVT speed control strategy was formulated.Finally the whole vehicle mode was built in CRUISE software,and the vehicle control strategy was established based on MATLAB/Simulink/Stateflow.Import the control strategy to the CRUISE and setting computing tasks.The economy simulation under the best economic efficiency CVT speed ratio is carried out and the dynamic performance simulation under the best performance CVT speed ratio is carried out.The simulation results show that energy management strategy based on logic threshold method and driving condition control strategy in the vehicle to meet performance and achieved better economic performance.The strategy under the best performance CVT speed ratio satisfied the performance requirements.and ensured that the limit of the driving wheel torque according to the wheels do not slip torque distribution under the small attachment coefficient road conditions.