A disk-type bearingless motor for use as satellite momentum-reaction wheel

This paper describes the development of disk-type bearingless motor for application as a satellite momentum/reaction wheel. It does not rely on mechanical bearings, so does not require lubrication and can be expected to have longer maintenance-free lifespan that is important in space applications. The proposed motor has a shaft-less disk-type rotor sandwiched between two disk-type stators and has the capability of both rotation and levitation control. The rotor is also the flywheel of the system. The desired degree of freedom (DOF) of rotation about z-axis motion is actively controlled while the other 5 DOFs are restricted actively or passively. Moreover, it has higher energy per weight and is smaller than the structure of a conventional motor levitated by shaft-based magnetic bearings and therefore is more suitable for space application where the space and weight are of much concern. Three-dimensional finite element simulation results are presented to support the proposition