Study On The AMT Shifting Control Strategy For Electrical Vehicle

Electric vehicle which is built with integrated system of motor and transmission could obtain optimal economic and power performance at the same time.Driving motor’s ability of precise speed and torque control can improve gear shifting quality.Targeting to the integrated powertrain system of driving motor and automated mechanical transmission(AMT)without clutch and synchronizer,this paper gives the match and optimization on important parameters of the powertrain system,and followed by relevant researches into the gear-shifting pattern and gear-shifting control strategy.The driving motor’s parameters are proposed according to the overall design requirement on the electric vehicle.A new dynamic speed ratio optimization method is put forward for the AMT system,which the speed ratio is set as the design variable to establish the target function considering the economy,power performance and light weight design of the vehicle.By means of the niche multiple-objective particle swarm algorithm,dynamic optimization of the speed ratio of the transmission system is realized through judgment regulation on gear shifting point and MATLAB/Simulink-iSIGHT software platform.Compared with the simulating results by using static optimization method,the new optimization method on the speed ratio of transmission system is verified.By analyzing the influence of the gear shifting points on the economic and power performance of the vehicle,the energy consumption of the vehicle and the sum of acceleration speed differences on different gear shifting points are used as target function.The electric vehicle’s speed at the gear shifting point and the gear shifting delay time are selected as the optimized variables.A comprehensive gear shifting pattern optimization model is established covering both the economic and power performance.Multiple-objective genetic algorithm is used to optimize the gear shifting points and gear shifting delay in the model.Three parameters,including vehicle speed,acceleration pedal position,and vehicle acceleration,are set to be fuzzied as the input,and the driver intention is obtained quantitatively.Different shift schedule can be adopted for different driver’s intention.Based on the analyzing of the gear shifting quality of the integrated powertrain system,this paper unfolds a dynamic analysis on different stages of the gear shifting process.The dynamic control models on each stage are obtained.The control strategy during the gear shifting process is proposed and simulated.In order to satisfy the requirements on synchronized adjustment of motor speed and recovered torque control,auto-tuning fuzzy PID control method based on active synchronized motor control strategy and the torque control recovery strategy based on driver intention are proposed.The simulation results give a verification.The bench testing system is established.First of all,the gear shifting execution mechanism,as well as the motor speed and torque adjustment ability,were verified through AMT static gear shifting experiment.The control strategy of active and synchronized gear shifting of motor,and the torque recovery strategy based on driver intention are verified.The feasibility of the paper’s gear shifting control strategy is evaluated by a series of indexes such as gear shifting time,active synchronization time,motor torque and speed variations,as well as the gear shifting success rate.