There are a number of problems with disposable centrifugal blood pumps (DCBPs) that need to be addressed. First, there is the high cost of the disposable pump head due to the use of rare earth magnets; secondly, the large size of the reusable part due to the additional torque transmission structure; and thirdly, the complex shape of the secondary flow channel due to the space allocated to the magnetic bearing and the magnetic coupling. In this paper, we propose a bearingless motor utilizing a compact permanent magnet free structure, which can be applied to a DCBP and also satisfies the requirements of having a low cost disposable pump head and a smooth secondary flow channel. The radial motion and angular velocity of the rotor are actively controlled, and the axial and tilt motions are passively stabilized by a magnetic reluctance force. In a prototype bearingless motor, the permanent magnet free rotor could be levitated and rotated at angular velocities of up to 3400 rpm with a rotational positioning accuracy of less than ±27 μm which is sufficient for extracorporeal circulation support. The experimental results demonstrate the feasibility of using the proposed permanent magnet free bearingless motor in a DCBP.
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