Comparison Between Different Air Gaps and Rotor Magnet Geometries of a Scalable Axial Flux Motor with Standard Core Laminations

A novel Scalable Axial Flux Motor with standard core laminations (AxMDM) and with a disc rotor made of glass fiber reinforced plastic (GRP) equipped with NdFeB-Magnets was developed and assembled. This novel machine concept is easy to fabricate, highly scalable, shows a high torque to weight ratio and has an excellent utilization rate of magnet material per torque.However, speed-dependent eddy currents in the rotor magnets significantly influence the magnet temperature, which has to be limited due to its maximum permissible values. Furthermore, the magnet temperature affects torque, maximum speed, power losses and the mechanical stability of the motor. These parameters can be adapted by adjusting the magnet geometry and the air gap, reducing the influence of eddy currents. The motor concept, measurement results and a correlation between air gap and magnet geometry versus magnet temperature and power losses are discussed in this paper.