Measurement of Rotor Eccentic Distance in a Maglev Centrifugal Blood Pump

Three passive magnetic bearings developed by the authors have been applied to the impeller blood pumps. The measuring system with hall sensors is built for determination of the maximal rotor eccentric distances in the pumps. The results show that when the rotating speed exceeds 4000rpm and the mass flow rate exceed 4 L/min, magnetic levitations can be achieved in the rotor with I-type bearing because the rotor eccentric distance is less than the gap(0.15 mm) between the stator and the rotos. Both in the rotor with I-type bearing and the rotor with II-type bearing, the maximul rotor eccentric distance decreases with the rise of rotating speed and mass flow rate. Among three passive magnetic bearing, the I-type bearing has better performance.