Novel Bearingless Segment Motor Design with Axial Magnetized Rotor Magnets

Bearingless motors and active magnetic bearings work completely contact- and wearless. With these properties, hermetically sealed and lubricant free rotating systems for various applications can be designed. It is possible to stabilize three degrees of freedom by reluctance forces, when a permanent magnet excited rotor disc is used. This constructional design is called bearingless slice motor. The bearingless segment motor is a subtype of the slice motor, featuring a segmented stator composition. This paper comprises the design process of a novel bearingless segment motor with axial magnetized rotor magnets, five stator elements and concentrated windings. Finite-element-simulations are applied to maximize the bearing forces and the motor torque per ampere and minimize the reluctance forces. However, the mathematical model of the system is nonlinear, so an appropriate nonlinear control scheme has to be applied to put the system into operation. The introduction of a prototype together with measurements completes the paper.