Development of Radial Type Self-Bearing Motor for Small Centrifugal Blood Pump

A small magnetic levitated centrifugal blood pump using a radial type self-bearing motor has been developed for use as an implantable artificial heart. In order to realize an implantable small centrifugal blood pump for a small adult patient, miniaturization and high efficiency of the device are necessary. In this study, a radial type self-bearing motor which is small-diameter and thin was developed, and magnetic suspension characteristics were measured. And, a magnetic levitated centrifugal blood pump using the self-bearing motor was developed, and pump performance and levitation performance were measured. In the self-bearing motor, the plus minus two-pole algorithm is adopted to levitate and rotate the rotor. The plus two-pole algorithm type and the minus two-pole algorithm type were developed to compare the magnetic suspension force in the radial direction. The minus two-pole algorithm type had very good control ability in the radial direction. The passive stability performance in the axial direction was enough ability to suspend the rotor-impeller. The restoring force was possible to be varied by the rotation magnetic field. At the operating condition with a flow rate of 5 L/min against a pressure of 100 mm Hg, the oscillation amplitude in x, y, z direction were 0.014 mm, 0.014 mm and 0.039 mm, respectively. And, the total power consumption was 7.1 W. The developed small magnetic levitated centrifugal blood pump has demonstrated sufficient levitation performance and low total power consumption. The average displacement in z direction of the rotor-impeller was possible to change by changing the phase angle of the rotational magnetic field.