Stabilized suspension control considering armature reaction in a d-q axis current control bearingless motor

This paper presents a novel control strategy to stably support the rotor shaft when a bearingless motor (BELM) based on d-q axis current control is driven under loaded condition. In this type BELM, the magnitude and direction of the suspension force are unfortunately varied depending on the rotor rotation, which causes the unstable rotor levitation during the motor operation. Thus, the compensation method of the suspension force has been proposed by the authors earlier and its effectiveness has been verified by a prototype machine. However, it is possible that the magnitude and the direction of suspension force are varied with armature reaction under loaded condition. It causes the serious problem in the rotor levitation. In this paper, thus, it is obviously found how the compensation coefficients are conducted to realize the stable rotor levitation even under loaded condition. The effectiveness of the updated compensation coefficients is confirmed in simulation based on a machine model designed by Finite Element Method (FEM) software and the experimental test results.