Modeling Of Two-Gear AMT Shifting Process And Study On Shifting Control Strategy For Pure Electric Vehicle

Shifting shocks and long shfting time problem exists in the traditional internal combustion engine vehicles equipped with AMT.Driving motor has excellent and accurate speed regulation ability and fast torque response ability.This can greatly improve the above problems by using the driving motor to coordinate with the shift motor in the shift process of the pure electric vehicle shift system equipped with clutchless AMT,at the same time,the dynamic and smoothness of the system can be improved.The dynamic performance and smoothness of AMT system are mainly affected by the control parameters in the shifting process.The study of the control problem in the shifting process can not be separated from the accurate dynamic model of the shifting process.Therefore,an accurate dynamic model of the shifting process is established and the influence of the control parameters on the shifting quality is analyzed in order to improve the dynamic performance and smoothness of the system and to optimize the shifting timing reasonably.It is of great significance to formulate reasonable shifting strategies so as to improve the economy of the system.In this paper,the clutchless two-gear AMT of pure electric vehicle is taken as the research object,and the following research is mainly carried out:(1)Study on Optimization of two-gear AMT shift strategy for pure electric vehicle.A two-parameter shift strategy based on vehicle speed and pedal opening is formulated,and a dynamic and economical shift strategy is formulated.With the goal of minimizing vehicle power consumption and using dynamic programming theory,the optimal gear shifting strategy is solved,and the optimal gear sequence under different working conditions is obtained;The effects of three different gear shifting strategies on vehicle economy are analyzed through simulation.(2)Analysis and Modeling of Two-Gear AMT Shifting System for Pure Electric Vehicle.Firstly,the structure of gear shifting system is analyzed.On this basis,the force analysis of the engagement sleeve between gear shifting actuator and synchronizer is carried out.The process of gear shifting is divided into four main processes: pick-up,clearance elimination,sleeve and ring engagement,sleeve and gear engagement.At the same time,aiming at the phenomenon of teeth beating in the process of engagement,the causes of teeth beating are analyzed,and the collision dynamics model of the process is established,and the switching conditions of each process of the dynamics model are analyzed in detail.(3)Simulation and Analysis of Two-Gear AMT Shifting Process for Pure Electric Vehicle.Aiming at the phenomena that shift control parameters affect shift time and shift impact in the process of shifting,a simulation model of shift process is established by using MATLAB/Simulink on the basis of the established dynamic model.The influence of control parameters on shift quality including shift time,shift impact and synchronizer sliding power is analyzed by simulation.At the same time,aiming at the phenomenon that the shift quality is different due to the difference of the relative position between the sleeve and the engagement gear,the dynamic simulation analysis is carried out to study the influence of the sleeve and the engagementgear on the vehicle dynamic performance and driving comfort.(4)Bench test of two-gear AMT for pure electric vehicle.The control strategy of gear shifting process was formulated,and the test bench of two-gear AMT for pure electric vehicle was built,and the gear shifting strategy was tested and verified.