Study on Control Strategy of Mode Switching and AMT Shifting for a Full Hybrid Electric Vehicle with Single Motor
|Keywords||Full hybrid electric vehicle Automatic manual transmission Modeswitching Shift quality Objective evaluation|
A hybrid electric vehicle (HEV) is a type of vehicle which combines aconventional internal combustion engine (ICE) propulsion system with an electricpropulsion system and energy storage devices. It can achieve optimal energydistribution by good matching and optimal control, which is perceived as today’s mostdevelopment potential new energy vehicle with low oil consumption and low emission.However, the control issues of HEV dynamic process become increasingly importantduring the research. Such as sharp ripple of output torque during mode switchingprocess and power interruption during AMT shifting process, which have seriousinfluence on performance and drivability. Therefore, the control of above dynamicprocess is one of the key technologies to promote the industrialization of HEVs.This rearsch is funded by the project of major science and technology project inChongqing City “Full hybrid Chang’an car key technology and prototyping”.In order toimprove the drivability of mode switching and AMT shift process for a full hybridelectric vehicle with single motor, the main researches are carried out as follows:①Analysis of the structural properties for the full hybrid electric vehicle withsingle motorThe structural characteristics of the full hybrid electric vehicle with single motorare analysised. And the parameters of the major components of the system are alsodetermined.Based on the characteristics of the dynamic coupling device with planetarygear mechanism, the rotate speed and torque characteristics of planetary gearmechanism are analyzed by use of lever analogy methord. The various operating modesare summeried to provide the basis for the following mode switching and AMT shiftstudy.②Mode switching control strategy of the full hybrid electric vehicle with singlemotorBased on the boundary conditions of the mode switching and the torque distributionof egine and motor in various operating modes for the full hybrid electric vehicle, thedriving mode switching patterns are classified according to the similarity of the modeswitching process. For the mode switching process of engine start during motor driving,the multistage coordination control strategy which integrates with motor torque andclutch pressure control in the engine start process, electric motor torque adjustment control after engine start is put forward. For the mode switching process of engine andmotor hybrid driving with clutch engagement, the coordination control strategy ofmotor speed and clutch pressure is proposed. For the mode switching process of engineand motor torque change with no clutch action, the coordinated control algorithmexpressed as the limit of engine throttle opening rate change, engine torque estimationand motor torque compensation is adopted. The typical mode switching process underthe drive conditions are simulated based on Matlab/Simulink and Matlab/Stateflowplatform. And the validity of the mode switching control strategies is verified.③Shift control strategy of AMT for the full hybrid electric vehicle with singlemotorAccording to the structural characteristics of the full hybrid vehicle, the integratedspeed control strategy of the motor and electronic throttle is adopted under shift processof engine driving mode. And the control strategy without cutting–off clutch and motoractive synchronistic is proposed under shift process of engine and motor hybrid drivingmode. The simulation is conducted based on MATLAB/Simulink platform to verify thevalidity of the shift control strategy under the two modes.④Objective evaluation for the mode switching and shift quality of the full hybrideclectic vehicle with single motorA set of evaluation indices is established to evaluate the mode switching and shiftprocess from the aspects of the performance and ride comfort. Based on the datasamples of evaluation index on the mode switching and the AMT shift quality, as wellas the appropriate driver’s subjective evaluation results, the method of genetic algorithmto optimize back propagation neural network is adopted to establish the objectiveevaluation model for mode switching and shift quality. Comparative analysis of thepredicting results of objective evaluation model and driver’s subjective evaluation iscarried out to verify the correctness of the objective evaluation model. Finally, therationality of the presented objective evaluation index is proved from the impactanalysis of the evaluation index numbers and the each evalaluation index on thepredicting results of the objective evaluation model.⑤Bench test for mode switching and AMT shifting of the full hybrid electricvehicle with single motorA test bench is built for the full hybrid system. The real-time control system isdeveloped by Matlab/Simulink and dSPACE real-time control simulation platform tool.The mode switching control strategy and shift control strategy are validated by experiments respectively. And the objective evaluation of the mode switching and shiftquality is conducted according to the experimental results by use of the objectiveevaluation model.In this dissertation, the mode switching and shift control strategy of the full hybridelectric vehicle with single motor are studied by theoretical analysis, simulation andbench test, the testing results are well consistent with simulation analysis. Theresearches in this dissertation provide a theoretical basis and experimental method forthe hybrid vehice control strategy development and industrialization.