Radial Motion Control of Axial-Flux Self-Bearing Motor Using Plus and Minus Two-Pole Magnetic Fields

This paper introduces an axial-flux self-bearing permanent magnet motor that controls motor torque, axial force, radial forces, and tilting moments by a single stator. A rotating magnetic field with the same pole number as the rotor controls the motor torque and axial force. Rotating magnetic fields with the rotors pole number plus and minus two poles control the radial forces and tilting moments. These fields generate both radial forces and tilting moments, and the direction of one of them becomes the same, and the other becomes opposite. Hence, we can control the radial forces and tilting moments independently. This paper describes the theoretical analysis of the radial forces and tilting moments and derives the control currents of stator windings. Levitation and rotation tests of a prototype motor confirm the proposed method.