Enhanced Torque Density of a Novel One-Axis Actively Positioned Single-Drive Bearingless Motor

A novel one-axis actively positioned single-drive bearingless motor topology with enhanced torque density is presented. The torque density is improved as follows: (i) The lower stator core was eliminated to cancel negative motor torque. (ii) The upper stator core was made of soft magnetic composite material (SMC) and integrated with supplementary windings. (iv) Wide air-gap length was also adopted to avoid radial touchdown. (iii) High residual flux density (Br) material was adapted for the rotor permanent magnets (PM). Motor torque of the proposed machine was improved up to 23% compared to the initial design.