Comparison Between Six-Phase and Three-Phase High-Speed Drag-Cup Induction Motor in Terms of Cup Losses

Constant demands for increasing power density and safety of drive units are very actual, especially in the automotive applications. This is the reason why high-speed machines have been in the research focus recently. They offer the possibility to decrease the volume for the same amount of delivered power, which is produced at higher speed but lower torque which is directly proportional to the machine dimensions. Moreover, the application of multiphase windings increases the safety margin and power density of the system. The focus of this paper is on the drag-cup induction motor which is suitable for high-speed applications because of its inherently low inertia. The paper extends the previous research in this field by introduction of a six-phase winding which is than compared with the previously designed three-phase variant. Comparison is based on the analysis of magneto-motive force (MMF) and magnetic field spectra and their influence on the drag-cup losses. Analysis is performed by means of FEM simulations of the current distribution in the cup due to different MMF harmonics.