  Bearingless motors use a single stator assembly to apply torque and magnetic
suspension forces on the rotor, making these machines compact with frictionless
operation and thus well suited to high-speed applications. One major challenge
that prevents wide usage of bearingless motors is the need for air-gap position
sensors, which are typically expensive. Here we present a method to estimate
the radial position of a hysteresis-type bearingless motor using the inductance
variation of the stator coils amplified by an injected high-frequency signal.
We have carried out finite element (FE) simulations to demonstrate its
feasibility, and have constructed a prototype self-sensing bearingless motor
for experimental validations.
