Self-sensing of the rotor position and displacement for an inset permanent magnet type bearingless motor

A rotor position and displacement estimation scheme using fluctuating high frequency voltage signal injection method was suggested, which will meet the need of low cost and practicable application for an inset permanent magnet bearingless motor (IPMBLM). Based on the motor space-saliency effect and the mutual inductance between the torque winding and the suspension winding of the IPMBLM, the rotor position and displacement can be observed simultaneously by injecting a fluctuating high frequency voltage signal into the torque winding. The analysis result using coupled field-circuit model demonstrates that the proposed method can realize the decoupling of sensed rotor radial displacement signals in the horizontal and perpendicular directions and of the sensed signals between the rotor radial displacement and the rotor position in a full speed operation region.