Coupling Analysis And Multi-objective Optimization Design Of Power Transmission System In Pure Electric Drive Vehicle

Power transmission system is an important part of pure electric drive vehicle in economy, safety and comfort aspects. Because technical foundation of electric vehicle industry in China is relatively weak, power transmission system becomes one of the technical problems for further development and promotion of pure electric drive vehicle.In this thesis, several structure schemes on two tranches automatic transmission for pure electric drive vehicle are designed. After comparing these structure schemes, the author considers that the two tranches-AMT transmission structure is suitable for China’s current national conditions. Based on national standard "Test Method for energy consumption rate and driving range of electric vehicle", the author selects basic urban cycle in urban road conditions as driving conditions, designs the motor according to the design parameters of a certain type of electric drive vehicle and establishes energy consumption per hundred kilometers model of electric drive vehicle.On this basis, the author uses transmission ratio, number of teeth and modulus as design variables, energy consumption per hundred kilometers, volume of transmission gear train as objective functions and the dynamic performance of vehicle, the size of transmission and the strength of gear as constraints to establish multi-objective optimization design model. Design parameters of the transmission are figured out through inputting the mathematical model to MATLAB and making the hierarchical order analysis. Compared with the conventional design method, the parameters of multi-objective optimization design are significantly lower in both energy consumption per hundred kilometers and volume of gear train.The author establishes the three-dimensional model of two tranches AMT structure transmission of pure electric vehicles according to the parameters of multi-objective optimization design, and then designs the transmission case. By taking ANSYS Workbench software as a platform, heat-structure coupling analysis of the gear is made with the help of sequential coupling method. The maximum contact stress of gear is consistent with the theoretical calculation of the maximum contact stress, which verifies the reliability of coupling analysis. The result of heat-structure coupling analysis with this method to the transmission case shows the design of the transmission case meets the strength requirement.Through the study, multi-objective optimization design method which takes energy consumption per hundred kilometers of pure electric drive vehicle and the volume of transmission gear train into consideration is proposed. The author checks the strength of transmission gear case by using the method of multi-field coupling analysis. This thesis provides a theoretical basis for China’s own R&D of power transmission system in pure electric drive vehicle.