Magnetic Suspension Performance of a Bearingless Brushless DC Motor for Small Liquid Pumps

This paper presents the experiment results from the testing of a magnetic suspension system in a bearingless brushless dc motor. This machine is suitable for use in small liquid pumps. The bearingless motor structure, the principle of the suspension force generation, and the magnetic suspension control strategy are proposed by the author. A prototype bearingless brushless dc motor is designed using computed results from a finite-element method simulation of the system. The simulation is experimentally verified using a prototype machine where the rotor is successfully suspended without mechanical contact when it drives a liquid pump at the maximum rotational speed of 2200 r/min and the maximum fluid flow of 8.2 L/min. This result shows that the proposed bearingless brushless dc motor is suitable as the drive for small liquid pumps.