Parameter Matching And Optimization Of The Powertrain System For Parallel Hybrid Electrical Tractor

Hybrid Electric Vehicle is one of the most efficient technologies to solve the problems which were caused by the limit of energy sources and environment pollution. It makes full use of the two power sources and can optimally match their power, thus it enhance the efficiency of the overall hybrid system. At present, the study on the HEV is mostly focused on the car and bus. For the time being, this paper is researched on the "Hybrid Electric Venue Freight Tractor" project. It concludes the study on the control strategy, powertrain parameters design and hybrid system optimization, aiming to develop a hybrid tractor to suit to the venue freight business. The major contents as follows:(1) First of all, summarize the status quo and research results of the hybrid powertrain system optimization, and conclude that reasonable optimization for the hybrid powertrain system will greatly improves the vehicle's dynamic, fuel economy and emission performance. At the same time, based on the full survey of hybrid electrical tractor potential market demand, it is importance and feasibility of tractor adopting hybrid electrical technology.(2) Analyze the multi-mode of the hybrid powertrain system for the hybrid electrical tractor, and based on the MATLAB/SIMULINK modeling environment, built the control strategy module. Combined with its dynamic as requested, study the influence of control parameters on vehicle performance, brought forward method of parametric design and evaluating system of hybrid control system, and accomplished parametric design for hybrid control system.(3) According to the multi-object and multi-variable optimization problem involved in the hybrid powertrain system, built its non-linear mathematical model with restraint functions. Based on the impact on the vehicle dynamic and fuel economic, select the pivotal parameters to optimize. Research on the genetic algorithm, and then construct optimization functions of weight coefficient, parallel selection and sharing function respectively. Final, applying these three types of genetic algorithm on the hybrid electrical tractor's powertrain optimization.(4) The optimization results demonstrate that the parameters from three-optimizing algorithm effectively improve fuel economy and reduce emissions without worsening power performance. Contrast and analyze the optimization results, and find out the most suitable algorithm, then, give many parameters optimization's Pareto optimal solutions.To sum up, this thesis's study on the hybrid control strategy, powertrain parameters design and hybrid powertrain system optimization for hybrid electrical tractor provides a theoretical guidance for the next physical experiment and real vehicle development with a high sense of reality. In particular, the optimization approaches proposed in this article, which were based on genetic algorithm, possess a broad sense of instruction for the power system optimization of other similar vehicles.