An Axial Flux Permanent Magnet Motor With Magneto-Rheological Fluid Brake Structure

In this article, to improve space utilization of the joint module composed of the axial flux permanent magnet motor (AFPMM) and the magneto-rheological fluid (MRF) brake, a machine topology that integrates the MRF brake structure into the radial side of an AFPMM is proposed. The proposed machine can operate in the rotation mode under axial load current and the brake mode under radial load current. The mathematical model of MRF brake torque is derived based on Bingham’s equation, and the damping characteristic of MRF to the rotor in the rotation mode is calculated and analyzed. In addition, the finite element analysis (FEA) of the proposed machine is carried out, including magnetic field distributions, air-gap magnetic density, electromagnetic torque, and brake torque. Based on the simulation results, the influences of flux leakage generated by the machine topology on the proposed machine are discussed in detail. Finally, after modifying the brake torque model and excluding the impacts of the rotor speed, brake torque versus different radial load currents is plotted.