Research On Short Time Withstand Current Capability Of DC Contactor For New Energy Vehicles

With the continuous development of new energy field,people’s demand for DC equipment is rising,such as electric vehicles,intelligent terminals and semiconductor lighting.DC equipment can not be separated from the protection of electrical components in use.DC contactor is widely used in electric vehicles,charging piles,solar power generation and other fields to complete the protection,control,measurement and communication of power system.Short time withstand current is one of the indicators to measure the safety performance of DC contactor for new energy vehicles,which represents the maximum current that the DC contactor can withstand in a certain period of time.In this paper,the short-time withstand current capacity of DC contactor for new energy vehicles is studied.By improving its short-term withstand current level,the electric repulsion force generated by large current can be avoided to drive the dynamic and static contacts of DC contactor away in a short time,and improve the safety performance of DC contactor.The main work of this paper is as follows:(1)In this paper,the solid modeling of DC contactor for a new energy vehicle is carried out,and the method of establishing conductive bridge model of DC contactor contact system using UG software is studied.(2)Ansoft Maxwell software is used to simulate the electric repulsion force on the model,and the influence of demagnetization block and contact structure on the electric repulsion force is studied.When the demagnetizing block with DT4 material is placed on the moving contact plate,the magnetic field distribution of the contact system can be changed,and the electric repulsion force of the contact system can be significantly reduced.When the input current changes from 100 A to 2000 A,the decrease range of the electric repulsion force is reduced from 52.23% to 32.83%;when the volume of the demagnetizing block is kept constant,the electric repulsion force will be reduced with the increase of the bottom area and height of the demagnetizing block;when the demagnetizing block water is used,the electric repulsion force will be reduced When the contact angle of the moving contact is changed to 45 degrees,the decrease range of the electric repulsion force is50.3%,and the decrease range does not decrease with the increase of the input current.(3)The optimal scheme is selected to develop the prototype of DC contactor,and the short-term withstand test is carried out to verify the simulation results.The experimental results show that the electric repulsion force can be significantly reduced by dividing one main circuit of the contact system into two circuits.When the input current is 6000 A,the DC contactor has no repulsion and welding phenomenon.Compared with the original prototype,the short-term withstand current level of the contactor is significantly improved.It has a certain reference value for the research and development of DC contactor technology.