Research On Driving Efficiency Optimization And Velocity Control Of Pure Electric Vehicle

In order to increase the cruising range of pure electric vehicles,two-speed transmissions and intelligent energy conservation control algorithms have drawn increasing attention,which includes eco-driving,economic cruise,and vehicle platooning.The parameter optimization of the two-speed transmission and the longitudinal velocity control under multiple interference factors are important basis of the related research.This article focuses on the optimization of the transmission ratio of the two-speed transmission and shift schedule,as well as the longitudinal robust speed control under multiple interference factors.The main research contents of this paper are as follows:(1)According to the two-speed electric vehicle performance index,the motor parameters and the transmission ratio are matched.The two-speed electric vehicle powertrain model is established by AMESim/Simulink.The dynamic shift schedule and economical shift schedule are designed,and the transmission shift strategy is formulated.With the goal of minimizing the energy consumption of the drive motor under NEDC operating conditions,the transmission ratio and shift schedule are optimized at the same time by using the genetic algorithm.An electric vehicle model with signal speed transmission is built.Then,the economy performance of a two-speed electric vehicle and a signal-speed electric vehicle are compared.(2)By analyzing the power transmission system of pure electric vehicles,it is clear that the main interference factors on electric vehicle longitudinal control are: parameter uncertainty,nonlinear aerodynamic drag,slope changes,measurement noise and time delay in network.Among them,measurement noise and time delay in network cause vehicle speed fluctuation.Parameter uncertainty,nonlinear aerodynamic drag and slope changes cause varying degrees of vehicle speed tracking errors.(3)In order to deal with the various interferences in the speed control of electric vehicles,a robust control approach for pure electric vehicle longitudinal speed tracking is proposed.Firstly,the driving resistance torque estimator was constructed to reduce the interference of the slope change and the nonlinear characteristics of air drag on the vehicle speed control.Then,the output feedback speed tracking controller was developed,and the following factors which may influence speed control performance are considered: the parameter uncertainty,measurement noise,driving resistance torque estimation error and time delay in control network.By constructing a new Lyapunov-Krasovskii function,the conditions for asymptotic stability of the closed loop controller were developed.By utilizing the linear matrix inequality technique,the control gains and performance index were obtained.Finally,a simulation experiment was carried out based on the MATLAB/Simulink platform.The simulation results showed that the robustness of proposed speed tracking approach is robust on different disturbances.