High voltage DC relays have small size and limited heat dissipation capacity.There is a risk of local overheating under long-term operation.It can even affect the contact stability and the working life of the relay when the heating is serious.Aiming at the 200 A DC relay,comprehensively considering the ohmic loss heating of the conductor circuit under power,and the natural heat convection,heat conduction and heat radiation of the relay in large space,the change of material resistivity with temperature and other factors,the bidirectional coupling model of the relays under rated working conditions is established,the resistivity change function with temperature is set,and the coupling calculation is performed.Finally,the corresponding temperature measuring platform of the prototype is built to verify the correctness of the simulation.The results show that the bidirectional coupling results are about 5.1% higher than the unidirectional coupling results,and the error with the experimental measurement is less than 6.2%,which can verify the validity of the bidirectional coupling of the electric heat flow field.
