Research On Automatic Shift Control Of Motor-Transmission Integrated Drive System For Pure Electric Vehicle

In recent years, with the rapid development of pure electric vehicle (PEV) industry and large-scale promotion of the market, people are paying more attention to the performance of PEV and the technology of PEV is beginning to develop towards an efficient integrated direction. Motor-transmission integrated drive system as the best configuration of PEV electric drive system which has become a hotspot research in related fields at home and abroad. Due to higher requirement of the drive motor control in the process of its automatic shift, especially on automatic shift control, the current domestic haven’t form a comprehensive and sophisticated control theory and method. So the target of this paper is research on automatic shift control of motor-transmission integrated drive system, aim to enact a reasonable and comprehensive coordinated control strategy for automatic shift to improve its shift performance.Firstly, a comparative analysis on different configurations of electric drive system revealed that motor-transmission integrated drive system is the best configuration of PEV. By analyzing the research status of integrated drive system at home and abroad, clear the research target and contents of this paper. According to the working performance and vehicle parameters of PEV, chosen permanent magnet synchronous motor (PMSM) and electrically powered electrically controlled automated mechanical transmission (AMT) form integrated drive system, and the parameters was matched.Secondly, according to the output characteristics of PMSM, used the shift schedule enact method of traditional automatic transmission developed a comprehensive shift schedule balance between power and economy. In order to improve shift performance, the automatic shifting process of integrated drive system was divided into three stages: uninstall-pick out gear, synchronize-put into gear and load-drive based on the feasibility analysis of AMT automatic shift without clutch, and the shift quality include shift time, shift shock and slipping power were analyzed at each stage. At the same time, studied on the torsional vibration characteristics of integrated drive system by analyzed the system dynamics model of pick out gear before and after. Then based on the torque and speed vector control method of PMSM, a coordinated control strategy for automatic shift was enacted.Finally, according to the functional requirements of coordinated control unit (CCU) in integrated drive system, the hardware system and software system of CCU were designed. The simulation model of motor-transmission integrated drive system was built in MATLAB/simulink, and simulation analysis of automatic shift was run under the settled conditions. Simulation results showed that the coordinated control strategy for automatic shift was proved to be correct and reliable, and shift quality of AMT was improved. Then the bench test for automatic shift of integrated drive system was carried out after test the CCU function, drive motor controllability and mechanism performance. Test results showed that the designed integrated drive system structure was reasonable, and realized its automatic shift function.