Analysis and Control of Nonsalient Permanent Magnet Axial Gap Self-Bearing Motor

This paper deals with a nonsalient permanent magnet axial gap self-bearing motor (AGBM), which is an electrical combination of an axial thrust bearing and an axial flux motor. A method for controlling the axial position and the rotating speed of the motor is also discussed. First, the development of the AGBM is briefly reviewed. The axial force and the rotating torque are then analyzed theoretically to establish an exact mathematical model for the motor. Finally, a modern control structure is derived to give the AGBM drive good dynamic behavior to make it suitable for practical application in industry. To demonstrate the proposed technique, a surface-mounted four-pole AGBM has been constructed and tested. The experimental results confirm that the motor works stably with the proposed vector control. Moreover, the AGBM can simultaneously provide noncontact levitation and rotation. This makes it an ideal replacement for conventional mechanical bearing motors in equipment used in harsh environments.