Study On Thermal Performance Of Electric Vehicle Connectors

In recent years,with the country’s advocacy of energy saving,emission reduction and low-carbon environmental protection,the new energy vehicle industry has made great progress.The connector is an extremely important part of a new energy vehicle,and is composed of four parts:a contact,an insulator,a housing,and an accessory.New energy vehicles use a large number of lithium batteries,and the power requirements of electric drive units are increasing.The operating voltage has increased to 400～600V in conventional cars,and the rated current has also increased from several amps to several hundred amps.Increasing current and voltage inevitably bring about a large temperature rise.Temperature is an important factor affecting the reliability of electrical connectors.When the connector works at a higher ambient temperature,its internal heat causes the internal temperature of the connector to rise suddenly,destroying the reliability of the connector,and even causing the connector to ablate and cause the vehicle to burn,affecting the safety of the car in use Therefore,the thermal analysis of electric vehicle connectors is of great significance.This subject takes an electric vehicle charging connector as the research object,and the theoretical calculations and finite element simulations are used to study the thermal performance of the connector.The main research contents are as follows:First,the structure of the connector is analyzed and simplified,and the thermal circuit diagram is drawn using the thermoelectric equivalent technology to obtain the relationship between the temperature rise and the convective heat transfer coefficient.Combined with dimensional analysis method and iterative method,the theoretical values of convective heat transfer coefficient and temperature rise are calculated.Compiling the MATLAB program according to the dimensional method and iterative method for calculating the convective heat transfer coefficient and temperature rise can save the calculation of the convective heat transfer coefficient.According to theoretical calculations,the curves of convective heat transfer coefficient and temperature rise with current are obtained.Then use the finite element analysis software ANSYS Workbench to perform thermoelectric simulation analysis on the connector of this electric vehicle to obtain the temperature distribution of the connector under the condition of flow,and explore the change of temperature rise with the current value and contact resistance.The critical resistance value at the rated current and the critical current value at the maximum contact resistance index of the connector are obtained according to the temperature rise index of the connector.The transient thermal simulation of the connector is performed to obtain the change of the maximum temperature of the connector with time.Finally,a simplified model of the connector is established,and the size and material of the connector are changed for thermoelectric simulation,so as to explore the influence of the size and material of the connector shell and insulator and the surface processing technology on the temperature rise,and propose an improved solution for the connector temperature rise.