Lorentz Type Self-Bearing Motor using Halbach Magnets

This paper proposes a 4-pole outer rotor type self-bearing motor which uses Lorentz force with Halbach magnet. It is expected to have good dynamic response and high levitation capability. For realizing high magnetic flux in airgap, Halbach magnet is used for the rotor. First, previous model of 8-pole motor is introduced and the associated problems are summarized. That is, the control forces for x and y directions were quite different and the levitation was unstable. For stable levitation, two sets of three phase coils were used and the system became complex. To overcome these problems, a new 4-pole and three segmented Halbach magnets are introduced. The fundamental principle is explained how the motor produces rotating torque and radial levitation forces. Finally, the motor is designed and fabricated. The levitated rotating test was carried out successfully. The top speed of 7400 [rpm] and the maximum motor efficiency of 72 [%]were recorded.