Matching And Control Strategy Research On Four Wheel Drive PHEV Power Train

Compared with electric vehicle,the plug-in hybrid vehicle cannot achieve the zero fuel consumption and zero emission,but it can realize the long distance running without the battery pack power limitation.And because the engine works with the motor coordinately,the PHEV has the better economy performance and emission performance than the traditional fuel vehicles.So the PHEV is preferred widely.By definition,the PHEV has at least two power sources.How to match the power sources system and transmission system and how to control power sources system coordinately plays a decisive role on the vehicle performance,so the research direction has important significance.In this paper,the four wheels drive PHEV is treated as the research object.According to the structure and characteristics of the vehicle,the power train parameters are matched,the vehicle control strategy is formulated and optimized,the vehicle simulation model is estimated,and the vehicle dynamic performance and economy performance are simulated.Specifically as follows:Parameters of the vehicle power train are matched.In this paper,the design requirements of the dynamic performance of the four wheels drive PHEV is set referring to that of a certain traditional fuel vehicle and national regulations and standards about PHEV.Then,the power source composed of engine and motor is matched according to the set design requirements of the dynamic performance and considering the logic threshold control strategy.On the basis of the matched power source,the transmission,the final drive and the single stage reducer are matched according to the design requirements of the maximum speed and the maximum gradient.At last,the battery pack is matched according to the design requirement of the pure electric driving range.The belt driven starter generator is matched referring to the hybrid electric vehicle equipped with BSG.The vehicle control strategy is formulated and optimized.In this paper,the logic threshold control strategy is formulated,which takes the engine as the main power and the drive motor as the auxiliary power.The maximum allowable power threshold of the pure electric mode is optimized according to the different driving cycles and driving distance.The vehicle required torque is taken as the condition of the model switchingand the vehicle driving mode is optimized in order to avoid the engine operating at high fuel consumption.By adjusting the output power of the motor and the BSG,the distribution of the vehicle required power is optimized in the hybrid driving mode and the driving power generation mode in order to make sure the engine works near the optimal economic line.The vehicle model is established and the vehicle performance is simulated.The four wheels drive PHEV model is established with Cruise,and the vehicle dynamic performance is simulated.The simulation result shows that the matched power train fully meets the design requirements of vehicle dynamic performance.The vehicle backward model is established with Matlab/Simulink,and the vehicle economic performance with the original control strategy and optimized control strategy is simulated on the different driving cycles and driving distance.The simulation result shows the vehicle economic performance with the optimized control strategy is improved partly in each case.