Analysis and simulation of a Lorentz-type slotless, self-bearing motor

A slotless self-bearing motor design is analyzed. The proposed design eliminates the trade-off between motoring torque and bearing force with respect to PM thickness found in many recent designs. Expressions for torque and radial force production are derived, including both control-type forces and destabilizing side-pull forces. The feedback control algorithm and simulated results are also presented. The analysis indicates that: (1) independent torque and bearing force is achieved for a large number of PM pole pairs; (2) the magnitude of both torque and bearing force increases with PM thickness; and (3) the motor is capable of stable operation as long as the winding current phase shift with respect to the PM flux is small.