Fault-Tolerance for a Centrifugal Blood Pump using a Two-DOF Controlled Magnetic Bearing

In our laboratory, an implantable centrifugal blood pump (CBP) with a two degrees-of-freedom controlled magnetic bearing (MB) to support the impeller without contact has been developed to assist the pumping function of a weakened heart ventricle. In order to maintain the function of the CBP after damage to the electromagnets (EMs) of the MB, fault-tolerant strategies for the CBP are proposed in this study. Using a redundant design of the MB, the magnetic levitation of the impeller was maintained with damage to up to two out of a total four EMs of the MB. Furthermore, with damage to three EMs, contact-free support of the impeller was also achieved by using hydrodynamic and electromagnetic forces.