Research On Integrated Control Strategy Of Motor And Transmission For Pure Electric Vehicle

Under the strong appeal of low-carbon and environmental protection,the Ministry of Environmental Protection issued the Limits and Measurement Methods for Emissions from Light-Duty Vehicles(CHINA 6),and the state had promulgated a series of subsidies for new energy vehicles,which have promoted the rapid development of pure electric vehicles.Since the external characteristics of the drive motor are similar to the ideal vehicle drive force field,the pure electric vehicles are still using a fixed speed ratio reducer.However,it has become an inevitable choice to use multi-gear transmissions instead of fixed speed ratio reducer in order to meet the needs of higher power and economy.In this paper,the motor and the two-speed automatic mechanical transmission(AMT)integrated power drive system were researched.The main contents of this paper are as follows:Based on the analysis of the structure and layout of the pure electric vehicle power drive system,the driving form of the motor integrated transmission was selected.According to the external characteristics of the motor,the parameters of the vehicle,and the performance design requirements,the drive motor's power,torque,and speed and the transmission's gear number and speed ratio were matched and calculated;The vehicle models was established in MATLAB/Simulink to verify the dynamic and economic goals of pure electric vehicles.Based on pedal opening and vehicle speed,the optimal dynamic shifting law with acceleration capability and the optimal economic shifting law with motor efficiency were formulated.Combining the dynamic and economy shift curve,the driver's power demand was judge by the power radio factor to formulate the comprehensive shift law.In order to balance the power and economy,the shift control law of the motor gear position is proposed.The vehicle demand drive torque replaces the accelerator pedal opening as an input,and controls the output torque of the drive motor to coordinate with the transmission gear position,so that the vehicle required driving torque remains unchanged and the driving efficiency is improved.Through simulation analysis,the motor gear integrated control shifting law can meet the power requirements.Compared with the comprehensive shifting law,the driving range and driving efficiency of the vehicle are improved.Structure of the no clutch two-speed AMT and the working principle of the shifting actuator was analyzed.According to the working mode of the driving motor and the running state of the internal mechanism of the synchronizer,the dynamics of the coordinated working phase of the drive motor and the synchronizer were studied during the shifting process.Based on this,a shift control strategy for coordinated control of the drive motor and shift execution structure was proposed.According to the requirements of shifting smoothness of the two-speed AMT,the shifting quality evaluation index of shifting time,jerk and friction work were proposed.The shift quality was optimized by particle swarm optimization algorithm of MATLAB during the shifting process.The results verified that the optimization effect of the jerk and friction work were better.The bench test and road test of two-gear AMT without clutch were carried out to test shift smoothness.The torque,speed of the drive motor and transmission gear during the upshift process on the test bench were analyzed to verify the coordination control strategy of the drive motor and the shifting execution structure,and the shifting time meets the requirements.In the road test,two-speed AMT shift quality optimization results was verified.The acceleration curve was analyzed to obtain the jerk curve of the shifting process.It proved that the maximum jerk satisfies the limit requirement and the shift smoothness was better.