Rotational angle estimation of Lorentz-type self-bearing motor using back-EMF

Abstract

Magnetic bearing motors have the advantages of no friction loss, no lubrication, and so on. However, these motors are not used widely because of their high cost and large size. To overcome these limitations, a self-bearing motor having a simple structure with distributed windings has been proposed. The rotor consists of a permanent magnet and an iron yoke that rotates within the body. The stator consists of two six-phase distributed windings and is installed between the permanent magnet and the back yoke of the rotor. A Lorentz force, generated by the interaction between the stator current and the magnetic field of the permanent magnet, controls the rotational speed and radial position of the rotor. The motor had used hall sensors to detect the rotational angle. In this paper, a sensorless controller without hall sensors is introduced. Finally, the performance of the controller is verified with rotational tests.