Magnetic suspension performance of a bearingless brushless DC motor for small liquid pumps

This paper presents the experiment results of the magnetic suspension in a bearingless brushless DC motor to apply in small liquid pumps. The bearingless motor structure, the principle of the suspension force generation and the magnetic suspension control strategy in the bearingless brushless DC motor have been proposed by the author. A prototype bearingless brushless DC motor has been designed based on the computed results by finite element method (FEM) to apply a small liquid pump. It is confirmed by the experiments using the prototype machine that the rotor is successfully suspended without mechanical contact when it drives a liquid pump at the maximum rotational speed of 2, 200 r/min and the maximum fluid flow of 8.2 l/min. This result shows that the proposed bearingless brushless DC motor is enough suitable as the drive for the small liquid pumps.