Design And Experiment Study Of A Micro Active Magnetic Bearing-Rotor System

In order to reduce the size of bearing to fit the artificial heart, magnetic suspended hard disk, gyroscope and etc, a new macro Active Magnetic Bearing-Rotor system is designed.Traditional Active Magnetic Bearings (AMBs) usually have five groups of bearings and sensors to control five degrees of freedom actively. The number of bearings and sensors are optimized to reduce the size of the AMBs. Considering the related design experience, we only use two groups of AMBs as the support to actively control two degrees of freedom inside a single horizontal plane, which is named as the main control plane. The other three degrees of freedom of the rotor suspended passively, whose support is offered by the component forces of two groups of bearings inside the main control plane. In order to decrease magnetic hysteresis loss, Magnetic poles are put along the axes of rotor and magnetic flux parallel the axes of rotor. Rotor is made of the integrative magnet conductive material to enhance the strength. Two groups of inductance sensors are utilized. The iron cores of both inductance sensors and magnetic poles are alternatively disposed. Treating with the signals of sensors, we can get the rotor coordinates in the main control plane and perpendicular displacements to the main control plane. Power amplified circuit is the type of linearity power amplifier. Self-oscillation is effectively restrained during the debugging.Based on this unusual structure, control current should satisfy certain restriction conditions to improve the stability of three degrees of freedom suspended passively. The control arithmetic is optimized. Through initial mechanical structure design and finite element analytical calculations, an experimental system is made to fulfill the stabilized suspension in the static state. And it works well. The size of rotor is analyzed and optimized during the debugging to get certain disciplines of air space selection.Experiment demonstrates that this optimized design is not only helpful to effectively reduce the size of bearing, but also to realize a good. The disposal methodof magnetic poles and sensors benefits further size reduction and control design. It is necessary to restrict the control current in order to improve the stabilized suspension of the other three degrees of freedom outsider the main control plane.