An Effective Way to Combine Radial and Axial Magnetic Bearings in a Unit

This paper proposes a new way to combine radial and axial active magnetic bearingsin a unit. The proposed active magnetic bearing (AMB) has no large axial disk and instead use the Lorentz force for axial control. Thus this AMB system can be more compact. Its structure is basically similar to the homopolar AMB with four cores circumferentially connectedby yokes. But it has two-layer windings for radial and axial controls; one is configured like a homopolar AMB, and the other is the same as that of a 4-pole heteropolar AMB. Since each winding can be used for radial control, the proposed system has two kinds of operating principle according to the radial control type. As for axial control action, it uses the Lorentz force generated by the interaction of the bias flux for radial control and the axial control flux. The feasibility of this scheme is experimentally verified by using a simple PD controller with a feedforward loop.