| In order to improve the shift quality,economy and power performance of hybrid electric vehicles,more and more hybrid electric vehicles are equipped with automated manual transmission.At present,the study of hybrid power transmission system mainly includes two aspects: one is the structural optimization of power transmission system;second,dynamic coordination and control of power system.Automated manual transmission has the advantages of high transmission efficiency,simple structure and low cost,but there is a problem of power interruption in the shifting process.In this dissertation,research of the shift control strategy without power interruption in hybrid power transmission system based on a P3 parallel hybrid bus which is equipped with an automated manual transmission(AMT)combined with the project of National Natural Science Foundation of China“Abrupt mechanism and instability control of transient switching stability of HEV working mode under extreme driving conditions”(51705208).The main contents are as follows:First of all,the structure characteristics and working mode of the power transmission system of the P3 parallel hybrid electric bus are analyzed and the model of engine and electric machine are built based on the test data.The equivalent vehicle simulation model of the test prototype is built based on Simscape.The dynamic performance of the parallel hybrid electric vehicle is verified by simulation which results verify the correctness of the model.Secondly,the different types of shifting strategy are analyzed,and the vehicle speed and acceleration pedal opening are selected as the shift parameters.The optimal economic shift strategy is adopted for the P3 parallel hybrid bus equipped with the automated manual transmission.The optimal economic shift curve is formulated,and the Stateflow model of shift strategy is established based on the Matlab/Simulink simulation platform.Then,based on the optimal control theory,the control of the engine?clutch and electric machine during the shifting process is divided into speed regulation stage and torque regulation stage.In the speed regulation stage,the derivatives of engine speed,clutch torque and electric machine auxiliary torque are used as control vectors.In the torque regulation stage,the derivatives of engine torque,clutch torque and electric machine auxiliary torque are used as control vectors.Take the minimizing friction work of clutch and minimizing the vehicle longitudinal jerk as the control goals,a linear quadratic optimal controller is designed.Then,through off-line simulation of the optimal controller can obtain the optimal trajectory curves of control vectors.Finally,the full vehicle simulation and prototype test of the gear shift controller are carried out under 50% acceleration pedal opening.The comparison and analysis are made with vehicle that without the optimal control.Because the shifting process is optimized in stages,the dynamic response control of the transmission system is more precise.The control strategy enables the drive torque to smoothly change during the shifting process,and the friction work of clutch and the vehicle longitudinal jerk are reduced. |
PDF Full Text Request