The 4 axes control magnetic bearing for a ventricular assist device

We propose simple homopolar magnetic bearings for a ventricular assist device. The bearings control radial position and inclination around radial axes of the outer rotor. In this paper, magnetic suspension characteristics of two types of the magnetic bearings which differ from each other in magnet arrangement or magnetization direction are compared using three-dimensional magnetic field analysis. The one is whose magnets are set on the outer rotor (Type A). The other is whose magnet is set on the stator (Type B). The radial control force and tilting control torque of Type A is 17% and 9.5% higher than that of Type B. The Type A magnetic bearing is made based on the analysis results and measured its magnetic flux density and axial restoring force. The bearing indicates the axial stiffness of about 2 N/mm.