Simulation And Analtsis On Shifting Performance Of AMT Transmission For Hybrid Electic Bus In Pure Electric Mode

New energy vehicles can effectively reduce the dependence on petroleum resources and exhaust emissions,and become a breakthrough to solve the environmental and resource problems caused by traditional vehicles.Considering the manufacturing cost,marketization and key technologies,hybrid electric vehicles have become the main development trend in all new energy vehicles.As an important component of the transmission system of hybrid electric vehicles,transmission efficiency and shift performance have a direct impact on the economy and power performance of vehicles.Due to the structural characteristics of AMT transmission and high transmission efficiency,it plays an important role in energy saving and emission reduction in hybrid electric vehicles.However,the power interruption in the shifting process,resulting in shifting impact,has become the main factor restricting the development of AMT transmission.This paper takes the AMT transmission on a single-axle parallel hybrid electric bus as the research object,aiming at improving the shift quality and shortening the power interruption time.In the process of shift,the active synchronization technology of motor and the fivesynchronizer shift structure are used to study the shift performance of the AMT transmission in the pure electric mode.First of all,the theoretical analysis and the virtual prototype simulation analysis method are used to study the engagement process between engagement sleeve and engagement ring of AMT transmission.The engagement process is divided into four stages: free sliding stage,tooth tip collision stage,tooth tip friction stage and inter-tooth meshing stage,to establish a mathematical model.The dynamic model of the engagement process was established by ADAMS.The simulation model is compared with the theoretical calculation value,and the error was 7.3%.The effects of the speed difference between the meshing sleeve and the engagement gear ring and the shift force acting on the meshing sleeve on the meshing process were studied,and,and the optimum range of the speed difference is obtained.The research results of the study can provide critical guidance for automatic shift control.Then,according to the active synchronous shift technology of motor and the structural characteristics of asynchronous AMT transmission,the power interruption time,gear impulse and impact are proposed as the evaluation indexes of shift quality.The direct torque control model of permanent magnet synchronous motor and the speed control model of PI controller are established.The control strategy of motor speed synchronization is proposed.On this basis,the active synchronous shift process of motor under pure electric mode is analyzed.Finally,in MATLAB/SIMULINK,the transmission system shift simulation model of single-axle parallel hybrid electric bus under pure electric mode is established,and the shift process is simulated and analyzed to verify the correctness of the motor active synchronization strategy.