A coaxial magnetic gearbox with magnetic levitation capabilities

Magnetic gearboxes (MGBs) are now a powerful alternative to their conventional mechanical counterparts in terms of reduced maintenance requirements, improved reliability, tolerance to mechanical inaccuracies, and inherent overload protection. MGBs have been proposed for numerous applications especially compact harsh environments subjected to severe shocks and vibrations. MGB designed with high gear ratio for only one transmission stage is an appropriate candidate for high speed applications. In this paper, the conventional planetary magnetic gearbox is equipped with a three-phase winding to provide additional magnetic levitation capabilities besides torque transmission. This can be tackled by adding a three-phase winding in the space between the ferromagnetic pieces. The current in this additional winding is controlled to provide decoupled axial forces irrespective to the transmitted mechanical power. This feature is important to reduce the mechanical losses especially for high speed rotor and can be a viable method for vibration suppression.