Research On Shifting Control Strategy Of Pure Electric Vehicle Equipped With Two-Speed AMT

As the increasing pressure of energy crisis and environmental pollution,energy saving and emission reduction is strongly demanded,pure electric vehicle(PEV)has received wide attention due to its zero emission and no pollution.With the requirement of economics,dynamics and comfort becomes higher,the multi-gear transmission is considered better.While the structure and control of multi-gear transmission is too much complicated,the two-speed automatic mechanic transmission(AMT)with simple structure and uncomplicated control becomes favored.This thesis relies on a cooperative project "electric vehicle powertrain matching optimization and integrated control" between Chongqing University and a company,researches on power transmission system modeling,shifting actuator parameters matching,shifting schedule and shifting control strategies of the PEV with two-speed AMT.The main works are as follows:(1)Based on the two-speed AMT of pure electric vehicle,the vehicle system model is established.The economic performance simulation model is established using backward modeling method;the dynamic performance simulation model is established using the forward modeling method.And taking the minimum power of the shifting motor as the target,the key components of the shifting actuator are determined.(2)A optimal economic shifting schedule considering motor and transmission efficiency,which is based on the traditional optimal economic shifting schedule,is established,and compared with traditional economic shifting schedule on Matlab/Simulink.platform As the driver's intention,the running state of the vehicle and the influence of the vehicle driving environment considered together,a comprehensive shifting schedule of the two-speed AMT is proposed.The simulation results show that the comprehensive shifting schedule considers both economic and dynamic performance when the vehicle runs on a straight level road;The comprehensive shifting schedule can correctly identify the dynamic factor,can considers both economic and dynamic performance when the vehicle runs on a light slope,and can avoid circuiting shifting as well when the vehicle runs on a middle slope.(3)The shifting quality and shifting process of the two-speed AMT for PEV is analyzed,and a specific shifting control strategy,which considers the comprehensive performance of shifting time,jerk and shifting work,is proposed.The simulation results show that the proposed shifting control strategy can realize fast and smooth shifting of two-speed AMT.(4)Taking a specific two-speed AMT as the research object,a comprehensive test bench for pure electric vehicle powertrain is built,and the vehicle control procedures test bench control interface for PEV is developed based on Matlab/ Simulink and d SPACE platform.Finally,the up and down shifting bench tests are conducted,and the comparison between the test and simulation results show that the two-speed AMT shifting control strategy proposed in this paper can achieve faster and smoother shifting.