Design and Performance of a Self-Excited and Liquid-Cooled Electromagnetic Retarder

To both overcome the serious thermal recession problem and conserve energy for conventional eddy-current brakes, a self-excited and liquid-cooled electromagnetic retarder (SL-EMR) assembly is proposed. The design includes a stator with an internally cooled channel, a rotor with multiple magnetic heads, and an integrated generator without brushes. The assembly and operating principles are analyzed. Models of the braking and generating systems are established. The electromagnetic field model analysis, braking performance analysis, thermal field analysis, and generator characteristic analysis of the SL-EMR are simulated using the finite-element method (FEM). The SL-EMR performance is bench tested, and the results show a 6% difference between the FEM results and the experimental results. The integrated generator provides adequate exciting current for the braking system. The braking torque decreases by only 10.4% during continuous braking conditions. The braking torque reached 2000 $hbox{N}cdot hbox{m}$ when the speed was 1500 r/min and the coil current was 30 A.