Study On The Comprehensive Shift Rule Of Two Speed AMT In Pure Electric Vehicle

The problem of energy consumption and exhaust emissions is difficult to solve,due to fuel vehicles,which promotes the development of pure electric vehicles.Pure electric vehicle has the characteristics of simple and controllable system,and has become a research hotspot.The two speed transmission(AMT)system can improve the performance of the driving motor,and make the vehicle have low speed and high torque,productive differential performance.These advantages attract researchers to develop the two speed AMT.In the shift process of a pure electric vehicle,there are instantaneous power interruption,shift impact and dynamic fluctuation.The shift rule has an influence on the economic performance of the vehicle.Therefore,the study of the two speed AMT integrated shift rule is great significance for improving the power and economy of the vehicle.When the two speed AMT shifts,there is a fluctuation of driving traction before and after shifting.It is necessary to control the fluctuation of driving traction and improve the comfort and power of vehicle.Through a large number of experimental data,it is found that speed of motor and the current of the drive motor controller are strongly correlated with the output torque of the motor.Therefore,the torque estimation model of the driving motor is designed.On the basis of the rough estimation model,the RBF neural network has the characteristics of arbitrarily precision approximation of any nonlinear function,and the torque is accurately estimated.Using the estimation torque to calculate the driving traction of the vehicle,the torque of the vehicle is calculated by using the estimated torque,and the torque needed to eliminate the driving traction fluctuation is analyzed.The basic driving control strategy of the motor is improved in real time,and the control strategy of the driving traction fluctuation is obtained.In order to further improve the economic performance of the two-speed AMT pure electric vehicle,the optimal shift rule is designed in combination with Pontryagin minimumprinciple(PMP)and the method of numerical analysis.On the basis of the power demand,the objective function of optimal control is established based on the minimum energy consumption,and the boundary conditions and constraint conditions are determined.Then,combining with PMP and numerical analysis,the optimal shift control law is obtained,and the optimal problem process is simplified,which Meets online,real-time,and discrete control requirements.According to the parameters of light pure electric vehicle and based on the similarity principle,the vehicle system is equivalent to a multi degree of freedom centralized mass system.The related components are in the form of concentrated mass,and the dynamic simulation test rig is designed.According to test of GB standards and test requirements,the measurement parameters are determined,and the evaluation criteria and experimental plans are formulated.The dynamic simulation test rig of transmission is applied to verify and evaluate the performance of shift process control strategy and optimal shift schedule.