General Analytical Models of Inductance Matrices of Four-Pole Bearingless Motors With Two-Pole Controlling Windings

In this paper, after introducing the bearingless motor's working principle in brief, we analyze the magnetic field distribution principle of the bearingless motor. We then derive in detail the general analytical models of inductance matrices of a four-pole bearingless motor with two-pole controlling windings. The derived general analytical models are applicable not only to bearingless motors with a salient-pole rotor, but also to bearingless motors with a cylindrical rotor. By setting different values of salient-pole arc width parameter rho in the general models of inductance, the analytical models of inductance of different types of bearingless motors, such as bearingless induction motors, bearingless synchronous reluctance motors, and bearingless surface-mounted permanent magnet (SPM) motors, can be derived.