Abstract: Aiming at the seriously overload braking problem of heavy truck, a permanent-magnet retarder based on the principle of permanent-magnet eddy-current braking is proposed as an auxiliary braking device, whose braking torque can be continuously adjusted. To solve the problem of braking torque decline and the magnet loss of permanent-magnet caused by high temperature due to long-time braking, a scheme of magneto-thermal two-way coupling is adopted and a magneto-thermal coupled model of the retarder is established with the magnetic permeability and conductivity of eddy disk as the mutual influencing factors in physical fields, and the braking torque characteristics of the retarder is studied with consideration of the effects of temperature, providing theoretical supports for the optimization design of the retarder. The trial manufacture and subsequent motoring bench test of several retarder prototypes with different materials and heat dissipation structures of eddy disk are conducted and the results show that with magneto-thermal two-way coupling, the simulated braking torque agree better with the tested one.

Key words: permanent-magnet retarder, eddy-current braking, magneto-thermal coupling, braking torque