A Permanent Magnet Free Bearingless Motor for Disposable Centrifugal Blood Pump

The disadvantages of disposable centrifugal blood pumps (DCBPs) are the high cost of the disposable pump head due to the use of rare earth magnets and the complex-shaped secondary flow channel due to the space allocated for the magnetic coupling. In order to overcome these problems a permanent magnet free bearingless motor for DCBPs with a smooth secondary flow channel has been developed. The radial position and rotational speed of the rotor are actively controlled, and the axial position and tilt angle of the rotor are passively stabilized by a magnetic reluctance force. Results of magnetic field FEM analysis showed that the proposed bearingless motor has an axial stiffness of 3.50 N/mm and a tilt stiffness of 0.87 Nm/rad. In an experiment, the power consumption of the prototype was less than 30 W without load at a rotational speed of 3000 rpm.