Research On Control Of Thermal Management System Of 25 Hp Electric Tractor

As a traditional agricultural country,the demand of agricultural machinery in China has steadily increased.With the increasing attention to energy and environmental,agricultural machinery is facing a transformation from internal combustion engine drive to motor drive.Compared with traditional fuel tractors,electric tractors have the advantages of no pollution and low noise.However,when the electric tractor is continuously farming,the electric drive system will generate a lot of heat.If the heat is accumulated,it will have a serious impact on the tractor’s operating efficiency,battery life,and safety performance.In order to ensure the efficient and safe operation of electric tractors,it is necessary to design a suitable thermal management system.At present,the electric tractor thermal management system usually adopts a simple air-cooling method to dissipate heat from the electric drive system,which not only fails to consider the thermal comfort of the driver,but also makes it difficult to control the temperature of the electric drive system accurately under the condition of high temperature and high thermal load.Aiming at the 25 HP electric tractor,this paper has carried out research from three aspects,which are cab thermal load analysis,thermal management system design and modeling,and thermal management system control strategy design,respectively.Firstly,based on the operational requirements of electric tractor,the parameters of motor and power battery are calculated and selected,and the structural parameters of the vehicle are obtained based on the design model of electric tractor.According to the principle of heat transfer,the thermal load of electric tractor cab,power battery and dual motor system is analyzed and calculated,and the design requirements of tractor thermal management system are put forward.Secondly,based on the cooling requirements of cab,power battery and dual motor system,a new tractor thermal management system is designed,and the circulation loop and working mode are divided.Combined with the thermal load value of the vehicle,the parameter matching of the main heat dissipation components of the thermal management system is completed.The tractor thermal management system is modeled accurately using AMESim,and the feasibility of the thermal management system scheme is verified by system performance simulation.Finally,combined with the temperature requirements of cab,power battery and dual motor system,the control strategy of thermal management system is proposed,and the controller is built though MATLAB/Simulink.In order to verify the effectiveness of the control strategy,a co-simulation platform for the thermal management system model and controller of electric tractors is established,and two typical working conditions of ploughing and rotary tillage under different ambient temperatures are selected.Through co-simulation of AMESim and MATLAB,the results show that the control strategy can make the thermal management system meet the temperature requirements of each part of the electric tractor effectively.