Temperature Rise Calculation and Optimization of Ceramic Sealed DC Contactor

Aiming at the geometric model of 300 A DC contactor for electric vehicle and its charging pile, three-dimensional finite element electromagnetic field and steady-state thermal analysis simulation are carried out based on COMSOL. In the equivalent treatment of the heat source, the influence of the contact resistance in the contact system and the coil resistance in the electromagnetic system on the temperature rise is emphatically considered. In the simulation, the heat conduction inside the contactor and between the contactor and the connecting copper bar, the convective heat dissipation and radiation heat dissipation between the contactor and the external environment are considered, and the convective heat dissipation coefficient of each outer surface is calculated according to the thermal similarity theory. Using this model, the effects of the cross-sectional area of the connecting copper bar, the contact pressure between the contacts, the shell material, and the coil wire diameter on the temperature field distribution are studied, and the optimal design suggestions for improving the temperature rise characteristics are proposed, which can provide a reference for the miniaturization and large capacity design of the contactor.