The torque decay is inevitable when Eddy current brakes (ECB) is continuously braking, which involves the interaction between electromagnetic field and temperature field. In this paper, based on the traditional magneto-thermal coupling model, a magnetic-thermal coupling model considering current decline (MCM-CD) is proposed to accurately calculate the torque decline curve. Through 3D electromagnetic field numerical analysis, the rule of heat generation rate of stator and coil was obtained. The temperature distributions of the stator and coil are calculated by the finite difference method, and the average temperature is used to modify the conductivity, permeability and current in the electromagnetic field model. The simulation and experimental results show that the MCM-CD can accurately calculate the thermal decline of the ECB. The proportion of torque decline caused by three factors is analyzed, among which the conductivity and current have a greater effect on the torque decline.

Magnetic-thermal coupling model,eddy current brake,thermal decay,current decay,experiment