Transmission Ratio Optimization And Shift Quality Research On 2AMT Of Pure Electric Vehicles

In recent years, due to the increasingly severe environmental problems and the soaring oil prices, more and more countries and OEMs began to pay attention to the development of pure electric vehicle. As an important part of the new energy vehicles, PEV(pure electric vehicles) is one of the seven strategic emerging industries in China. However, because of lacking core technology(battery technology), our pure electric vehicle industry developed slowly. As the core part of the PEV, the power transmission system has a great influence on the power and economy of the whole vehicle. Therefore, Reasonable choice of powertrain components and increase powertrain efficiency is one of the important means to improve the performance of electric vehicles.As a key component of the driveline, transmission plays a vital role in vehicle performance. In order to improve the efficiency of the drive motor and the combination of pure electric vehicles matching items, this paper will be fixed ratio into two transmission ratio. Then, using the particle swarm optimization algorithm to optimize the parameters of the transmission ratio, it can improve the efficiency of the motor, thereby improving the vehicle’s power and economy. In addition, the paper use MATLAB/SIMULINK software and bench test for simulation and experimental verification to two speed transmission shift quality. And we verify the accuracy of the two speed transmission shift strategy through simulation and bench test results. The following research work is carried out in this paper:1) According to national standards on passenger electric power and economy requirements, determine the vehicle’s design goal. Based on the vehicle’s design goal, complete the matching work of vehicle power transmission system.2) Using CRUISE software to build a PEV power model. Introduce the process of building the model in details.3) Put the ratio of the main reducer and gear transmission ratio as the design variables; put the driving range of the CYC_ECE operating conditions and the starting acceleration time as the objective function; put the vehicle dynamic performance as constraint conditions, and then a multi-objective optimization mathematical model is set up. Finally, using the particle swarm optimization algorithm to optimize the mathematical model to obtain the ratio of two gears transmission and final drive.4) Research on the shift quality of the two gear automatic transmission, put the degree of shift impact as a shift quality evaluation index. Then, using MATLAB/SIMULINK software to build 2AMT model and vehicle dynamics model, get the shift impact degree of the curve by simulation and bench test to verify the validity of the two gear automatic transmission shift strategy.5) Using the CRUISE vehicle model obtain the dynamic and economic changes. The simulation results show that using two automatic transmission vehicles can improve the performance and fuel economy. This demonstrates that using particle swarm algorithm is feasible for the optimization of the electric car transmission ratio.