Bearingless Five-Axis Rotor Levitation with Two Pole Pair Separated Conical Motors

In some high performance applications, such as high speed rotating machinery, systems where access for maintenance is limited, or operating environments with extreme temperatures and pressures, motors without mechanical bearings would be preferred. This paper presents the theory, simulation, and lab results of a new type of fully magnetically levitated bearingless motor. The motors are wound without internally connecting the pole pairs, and force is controlled by varying rotor reference frame d-axis current to each pole pair. This in turn raises or lowers the flux caused by the permanent magnets, creating a flux imbalance on the periphery of the rotor, which in turn creates a net force on the rotor. The conical shape of the motor allows forces to be created in both radial and axial directions, allowing these motors full 5-axis levitation.