Parameter Optimization Design Of Plug-in Hybrid Electric Vehicle Based On Reflux Power Transmission System

Due to the feature of low energy consumption and low emissions,the plug-in hybrid vehicles have become a hot topic in recent years.The reflux power transmission system is a new type of power coupling transmission device,which has the characteristics of high transmission efficiency,full continuously variable speed regulation,and large speed ratio range.It is the first time to apply the reflux power transmission system into the plug-in hybrid vehicle,which breaks the limitations of the previous patent.In order to combine the two characteristics to achieve good power and economy,the parameter matching optimization of the whole vehicle has significant research significance.In this paper,some research based on the plug-in hybrid vehicle were carried :According to the requirements of the dynamic performance of plug-in hybrid vehicles,the longitudinal dynamics model of the whole vehicle is constructed.Based on the knowledge of automobile theory,the parameters of the key components in plug-in hybrid electric vehicles such as electric motors,engines and power batteries were matched and the types were selected.Meanwhile,the motor efficiency,engine efficiency and number of power batteries were determined,and the efficiency model was established.The basic structure and working principle of the reflux power transmission system are introduced.On this basis,the characteristics of speed ratio and efficiency of the system are calculated,and the working range and switching conditions of the system’s reflux mode and CVT mode are determined.According to the characteristics of the reflux power transmission system,the parameters were matched such as the CVT type of the transmission system,the fixed speed ratio gear structure,the planetary row structure,the maximum and minimum speed ratio of the whole vehicle and the final speed ratio of the transmission,to ensure the transmission efficiency,and larger speed ratio.Meanwhile,the efficiency model of the transmission system is established.The various operation modes of the plug-in hybrid vehicle were introduced,and the torque distribution principle and switching conditions of each mode were formulated.On the basis of considering the efficiency effects of various components of the vehicle,an equivalent input power model was established for each mode.By optimizing the system speed ratio of the reflux power transmission system,the optimal input torque of the motor and engine in each mode was obtained,the same to the minimum equivalent input power.The minimum equivalent input power of each mode is compared,the working areas of each mode were divided,and the boundary between the modes was used as a mode switching rule to correct the previously formulated rules.The main influencing factors of powertrain efficiency were analyzed.The planetary row structure parameters and the final reducer speed ratio were taken as structural parameters,and the economics of the whole vehicle were optimized considering the influences of other components of the whole vehicle,and the structural parameters with the lowest equivalent fuel consumption were obtained.The power parameters including the engine power and motor power and the control indexes that affect the mode switching law were optimized by genetic algorithm,which used the 100 km equivalent fuel consumption as the objective.The optimization results show that the 100 km equivalent fuel consumption was reduced by 6.86%,demonstrated the efficiency of the whole series methods proposed in this paper.