关键词: 前置缓速器, 气隙磁通密度, 液冷, 电热耦合, 制动力矩

Abstract:  A pre-transmission liquid-cooled permanent-magnet retarder（PMR） was proposed to solve the problems of braking torque heat-fade for conventional PMRs. The calculation models of static and transient air-gap magnetic field were established considering the influences of magnetic flux leakage in the retarders based on the magnetic equivalent circuit（MEC）and piecewise function method. The braking torque model of the PMR was obtained and verified by finite element analysis method based on the transient air-gap magnetic field model. An iterative model of braking torque considering the influences of temperature was established based on the established braking torque model and the electro-thermal coupling theory. The bench test results show that the calculated values of the braking torque model are in good agreement with the braking torque-speed characteristic test. The torque values calculated by the iterative model of braking torque considering the temperature effects are in good agreement with the continuous braking test results， and the errors are less than 7%. 

Key words: pre-transmission retarder, gap flux density, liquid cooling, electro-thermal coupling, braking torque