Optimization of the rotor geometry of a high-speed interior permanent magnet bearingless motor with segmented magnets

Bearingless motors combine the torque generation of electrical motors and the radial suspension force capabilities of traditional magnetic bearings. The magnetomotive force (MMF) distribution in the motor generates radial force interference. The interference force affects the angle between the actual and desired radial force. This angle is called the force error angle. For stable levitation of the rotor of the bearingless motor the force error angle must be minimized in the design phase of the machine. This paper presents an optimal rotor structure for minimization of the error angle in a high-speed interior permanent magnet bearingless motor with magnets embedded in the rotor surface.