Research On Three-parameter Shift Schedule Of Two-gear AMT Pure Electric Vehicle

Despite the sluggish growth of auto sales in recent years,new energy vehicle have maintained a rapid growth,among which pure electric vehicles are the main growth force.At present,most of the pure electric vehicles in industrial production are equipped with single gearbox,which makes the drive motor unable to obtain the optimal economic performance,resulting in the waste of effective power of the drive motor,so it is necessary to study the multi-block of pure electric vehicles.The gearshift schedule is the most important part of the multi-gear transmission control module,which not only determines the shift time,but also determines the power and economy of the vehicle to a certain extent,thus affecting the driving range of pure electric vehicles.In this paper,the transmission system parameters of two-gear AMT pure electric vehicle are matched and the corresponding model is built.Based on the unscented kalman filter to estimate the road slope,a three-parameter gearshift schedule including speed,throttle opening and road slope is developed.The specific work is as follows:(1)According to the design requirements of two-gear AMT pure electric vehicles,the transmission system parameters are calculated,the power,speed and torque of the driving motor are matched,and the two gear transmission ratios of the AMT are calculated and distributed;Build driver model,drive motor model,synchronizer model and vehicle model based on AMEsim.Based on Simulink,the vehicle control model and gearshift control model are established,and the co-simulation of physical model and control model is realized.(2)Estimate the slope of the road.The mechanism of the unscented kalman filter algorithm is explained,the vehicle longitudinal dynamics mathematical model is established,and the road slope estimator is designed based on the model.Based on the unscented kalman filter UKF,the real slope of the road is estimated,and the simulation analysis of the constant slope road surface and the step change slope road surface is carried out.Simulation results show that the error between the slope estimation results and the actual slope value is within a reasonable range.(3)Make three-parameter gearshift schedule.Based on the speed,throttle opening and road slope,two three-parameter shift patterns are developed to optimize the vehicle's dynamic performance and economy.Due to the close distance between the upshift curve and downshift curve of the economic shift rule in the case of low throttle opening,and the throttle opening is prone to sudden changes,frequent shift of transmission will be caused.By modifying the downshift curve,frequent shifting is restrained as far as possible without excessively reducing the economy,and finally improve driving comfort.(4)The transient control strategy of AMT transmission gear shifting was designed to make the gear shifting process conform to the gear shifting quality evaluation standard.The velocity following simulation was carried out in UDDS and NEDC respectively.The simulation results show that the speed following error is reasonable and the shift process achieves the design goal.The results show that the dynamic and economic performance of the gearshift are improved compared with those of the two parameters.The economic gearshift schedule with three parameters after modification is simulated,and the result shows that the frequency of shift is obviously less than that before modification.