Research On Matching Design And Liquid Cooling Of Battery Pack Of Electric Tractor

Tractor is one of the most widely used agricultural machinery products in agricultural development,but the shortage of energy and the strategic goal of national sustainable development put forward an urgent need to accelerate the research on electric tractor.The endurance performance and cycle life of battery at different conditions are the subjects of electric tractors.The subjects of this thesis based on the characteristics of 25 horsepower independent double motor drive electric tractor are as follows.Based on the design aims of independent double motor drive system,main drive motor and sub-drive motor are designed by the pull conditions of electric tractor.Then,the parameter of power battery pack is matched with the power requirement of sub-drive motor under plowing condition and the cycle life of electric tractor,and the connection mode of power battery pack is determined by the comparison of series/parallel mode of monomer battery.Then the layout model of electric tractor drive system is established with the arrangement of electric tractor’s rear axle.In order to verify the battery pack’s cycle capacity,AVL Cruise vehicle model is constructed based on the design parameters of independent double motor drive system,the electronic units of electric tractor are controlled by Simulink strategy models,and the maximum speed and maximum climbing inclination of electric tractor,as well as different condition of plowing,rotary and transition,are verified by the couple method of AVL cruise and MATLAB Simulink model.First,the thermal characteristics and reaction mechanism of monomer lithium iron phosphate battery are analyzed,and the thermal parameters of monomer battery are calculated based on Bernardi thermal theory.Second,the temperature rise characteristics of monomer lithium iron phosphate battery at different discharge rates are analyzed by the Workbench simulation method and battery charge/discharge test method.Then the effectiveness of the simulation model is verified.At last,the effect of battery pack temperature distribution under different ambient temperature and liquid flow was studied with liquid cooling system of 25 horsepower electric tractor’s power battery pack.The results show that the layout of the electric tractor drive system designed is basically realizable,the cycle capacity and thermal dissipation performance of the power battery pack meet the design aims of 25 horsepower independent double motor drive electric tractor.