Research On Heat Transfer Characteristics Of Cooling System Of High Power Charging Connector

As a significant part of green energy vehicles development,high power charging technology will be widely used in green energy vehicles because of its advantages such as high power,fast charging time and good compatibility performance.However,the temperature rise will increase rapidly in a short period of time under the condition of high voltage and high current which results in thermal safety problems.This thesis designs a kind of cooling system which is suitable high-power charging,and focuses on the theoretical analysis and simulation of heat transfer characteristics,the main contents are as follows:(1)The mathematical model of heat generation of charging cable is established,and the influence rules of load current,cross-sectional area of cable core and cable length on the heat loss power of charging cable are obtained by simulation,a cooling system is designed to solve the problem of fast heat dissipation,the flow and temperature rise of cooling system are calculated and analyzed theoretically,the overall size of the cooling system is optimized by considering small dimensions and simple structure.(2)Based on the theory of thermodynamic equation,the heat transfer calculation model of charging cable is deduced,and the three-dimensional simulation model of charging cable with cooling channel is established,the influence of parameters such as coolant flow rate,inlet temperature and cooling pipe structure on the internal temperature field distribution of charging cable under different working conditions is simulated.That is,the temperature of charging cable will increase with the increase of loading current,drop with the increase of coolant flow and number of cooling pipes,and drop with the drop of coolant inlet temperature,the maximum temperature of charging cable will drop by about16.4% when the central cooling arrangement is adopted.(3)The AMESim model of the general thermodynamic model with cooling circuit is established,and the heat transfer law between the cooling system and the high power charging connector is obtained by simulation.The research shows that the chargingconnector is overheating and the temperature distribution is uneven under the condition of natural convection heat dissipation when the cooling system is closed,the maximum temperature rise of the charging cable is 28.9?,and the temperature rise of the coolant is23.2? when the cooling system is fully open,taking the temperature rise of charging cable and coolant as control objects,a simple and practical temperature control strategy is proposed.(4)The test bench of cooling system for high power charging connector was built,so the effects of loading current and ambient temperature on the temperature rise of high power charging connector are studied experimentally,and the good heat dissipation capacity and good reliability of cooling system are verified.The experiment shows that the experimental temperature rise between the charging gun terminal and the environment is33.5? under the condition of loading 600 A current,which is lower than the temperature rise guideline of 50?.The temperature rise of the crimp area reduces by 36% when the cooling channel is added into the crimp area,and the temperature rise of the charging gun terminal reduces by 3%.After 10 days of experimental testing,the average temperature rise of the high power charging connector is 15.7? under the condition of loading 400 A current,which indicates that the cooling system of high power charging has good heat transfer performance and good stability.