Biased magnetic flux produced by a permanent magnet can reduce the power consumption of the suspension system in bearingless motors or magnetic bearings. However, the ability to generate suspension biased magnetic flux with a single permanent magnet tends to be saturated with the increase of the magnetising width. In order to solve the above problem, an axially superposed permanent magnet biased bearingless motor, which consists of a 12/8 reluctance motor for producing torque and two permanent magnets for producing desired biased magnetic flux density is present. The structure and working principle are introduced, and the electromagnetic characteristics are analysed by finite element analysis. The results verify that the proposed bearingless motor has the excellent merits of weak coupling between the torque system and suspension force and satisfactory suspension performance. Furthermore, much more biased permanent magnets could also be used for the suspension system of ultra-high speed, high power and slender bearingless motors such as flywheel energy storage systems.

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A new hybrid double stator bearingless switched reluctance motor (HDSBSRM) realizes the decoupling of torque and suspension force from the structure, and the permanent magnet added in the inner stator further reduces the suspension power loss. For HDSBSRM, loss is the main cause of temperature rise. In order to ensure the stable suspension and rotation of the motor, loss of the Magnetic Bearing (MB) and motor are calculated and analyzed by finite element method (FEM). Based on the loss result, the temperature field is analyzed. The analysis of loss and temperature field provides important theoretical basis for the design of motor cooling system.