Five-Axis Rotation Control of Lorentz Force Type Radial Gap Self-Bearing PMSM with Hexagonal Winding and Two-Pole Rotor

This paper introduces a five-axis active control of a self-bearing permanent magnet synchronous motor (PMSM) that using the Lorentz force. Recently, there has been an increased demand for the miniaturization and high performance of self-bearing motors that integrate magnetic bearings and motors. To meet this demand, a small self-bearing motor with a hexagonal stator winding and a two-pole rotor has been developed. The stator consists of two slotless, six-phase, distributed windings stacked in the axial direction. Designing one of the coil ends of the stator winding so that it does not overlap with the rotor PM generates an axial force. The radial force is controlled by supplying a four-pole current to the stator windings. Although the Lorentz force is smaller than the magnetic attractive force, it improves the performance due to its good linearity and reduced eddy current loss. Previous research used a four-pole rotor and diamond-shaped windings; however, this research uses a two-pole rotor and hexagonal stator windings to enhance axial force and radial force generation. This paper introduces the structure and the principles of the axial force and radial force generation. It also confirms the feasibility of the proposed motor through a levitation experiment with a prototype motor.