Levitation fluctuation constraint strategy in bearingless motor based on disturbance acceleration observation

The levitation fluctuation is unavoidable when bearingless motor is working. The motor´s working performance can be affected by levitation fluctuation. It is vital to constrain the levitation fluctuation. In this paper, a kind of consequent-pole bearingless permanent magnet-type motor is studied and levitation fluctuation sources are analyzed. Because the normal levitation control algorithm PID is not good at anti-disturbance, the radial disturbance acceleration observer of motor´s rotor is proposed. Based on the observed disturbance acceleration, a conception of equivalent disturbance current is proposed based on the relationship between disturbance acceleration and levitation control current. The equivalent disturbance current is introduced in levitation control to constrain levitation fluctuation. The simulation results show the proposed strategy can constrain levitation fluctuation and achieve steady operation when it is comparison with using PID controller only.