A Suitable Current Control Strategy for Split-Phase Bearingless Three-Phase Induction Machine

This paper presents a suitable current control strategy for a split-phase bearingless three-phase induction machine. This machine is constructed from an off-shelf four poles 1/4 HP induction machine by splitting their windings. The split point of each winding is grounded which results in two sets of three-phase windings phase shift 180deg from each other. The radial forces required for accomplishing the rotor shaft levitation and the required rotating torque is determined from a control strategy which determines the machine phase reference currents. These reference currents are unbalanced in phase and magnitude and they are regulated by two sets of double sequence machine phase current controllers which address a best performance of the proposed motor drive system. Experimental results are presented to validate the feasibility of the proposed motor drive system