Study On Powertrain Matching And Optimization For Parallel HEV

The development of new vehicle with lower fuel consumption and less emission has been an important mission to the whole automobile industry, since words like ’haze’ and ’oil-price’ has been everywhere in papers while more and more attention has been paid to the problem of Air pollution and energy crisis. HEV (Hybrid Electric Vehicle) which has both engine and motor as its energy sources, commendably combining the advantages of commercial ICE vehicle and electric vehicle, can efficiently reduce fuel consumption and emission. Therefore, the study of hybrid vehicle performance is of important significance.This paper focuses on the study of powertrain matching and optimization for parallel hybrid electric vehicle, by the combination of simulation optimization and experimental verification, to get the best vehicle performance.In this paper, a six-gear bus with traditional internal combustion engine as its only power source is set as the prototype vehicle, of which, on the premise of accessing relevant technical parameters, vehicle system simulation model is set up in AVL-Cruise software simulation platform for research with experiments verified.On the basis of this bus, HEV with both engine and motor as power sources is built. Logic threshold control strategy based on required torque rulings is written to control vehicle driving mode and torque portion, and then, of which suitable threshold are optimized by the function of multi-parameter in AVL-Cruise.After that, effect on vehicle performance of different degree of hybrid (DOH) is studied by matching different motors while engine selected. Based on results of simulation models, vehicle performance and cost among different DOH under several different road conditions is analyzed. The study also make an optimization of the DOH through multi-objective genetic algorithm, setting vehicle performance as multi-objective functions to seek for Pareto optimal solutions, which is the best DOH for this model. At last, experiments are taken to validate this method.Following that, gear box is optimized by changing gear ratio with Matlab program DOT. m, under the condition of meeting dynamics demands to set the ratio scheme, which is used in the AVL-Cruise to simulate different gear box ratio for the vehicle performance. At last, GA is used to find the best gearbox ratio, while net of BP artificial neural network which is trained from the simulation results is set as objective function. This study uses both an example of a sixteen-gear dumper and a HEV rack to validate this method to optimize gear box.Through the study above, powertrain of HEV is matched in this paper, focusing on the influence of DOH and the transmission ratio in vehicle performance, a complete set of matching optimization method is established to get higher performance, which can be widely used in optimization of HEVs with the same structure.