| Super mild hybrid electric vehicle (HEV) takes continuously variable transmission (CVT) with reflux power as transmission system. Taking advantage of its wide ratio range, super mild HEV possesses only motor mode, however, mild hybrid electric vehicle has not this mode. Super mild hybrid electric vehicle can improve the fuel economy and emission performance. Compared with mild hybrid electric vehicle, super mild hybrid electric vehicle has better prospect.This paper takes super mild hybrid electric vehicle as object of study, for the purpose of improving fuel economy and harshness, the main research work is introduced as followings:①Based on roundly clarifying the structure and work principle of continuously variable transmission with reflux power, the model of transmission system ratio and mechanical efficiency are built. Considering the effect of transmission and engine efficiency on instantaneous oil consumption, the relationship between instantaneous oil consumption and system efficiency is built.The impact of transmission system wide ratio range and planetary gearing mechanism structural parameters on system efficiency, takes k andαas the optimization design variables, adopting the method of optimization design based on the system efficiency maximization control strategy, derives the value of the optimal parameter k andα. Based on the platform of Matlab/Simulink, a comparison between the fuel economy of before and after optimization design.②Taking advantage of its wide ratio range, choosing small power motor as assistant power source, and matching parameters on main components. Analyzing on the principle of super mild hybrid electric vehicle, the work mode is divided into launch, driving and reverse mode. Aiming on the different work mode, draws up the judging condition of launch mode and control strategy on every mode, finally, the simulation experiment is done. Aiming on driving mode, classifying the four work modes. Adopting on the logic control strategy, the simulink experiment of driving cycle ECE+EUDC is carried out.③The judging condition on low gear ,high gear and transition gear of super mild hybrid electric vehicle are analyzed. Aiming on the method of RPCVT gear to CVT gear switching and CVT gear to RPCVT gear switching, which is further discussed, deriving that the control of clutch L1 and L3 is very important. Therefore building the dynamical model of clutch L1 and L3, for the purpose of meeting jerk, deriving the torque change rate range of clutch L1 and L3. Analyzing on switching type of super mild hybrid electric vehicle driving mode, drawing up control strategy on only motor mode switching to only engine mode, building dynamical and simulation model in the switching process.④Based on the key component efficiency model of super mild hybrid electric vehicle, building the system efficiency model on different driving mode. Taking system efficiency maximum as optimization objective, deriving the target speed ratio and system efficiency optimization model under driving mode. Comparison with system efficiency of different driving mode, deriving optimization operation region, then building the simulation model of super mild hybrid electric vehicle , the simulation experiment of driving cycle ECE+EUDC is carried out.
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