A 1-DOF Controlled Full Levitation Hybrid Magnetic Bearing for Compact Centrifugal Kidney Pumps

In magnetic levitation centrifugal blood pumps, most magnetic bearings have flat rotors, so this kind of magnetic bearings is not suitable for the rotor structure of centrifugal kidney pump with similar axial-radial dimensions. This paper combines permanent magnet passive levitation and electromagnetic active levitation to propose a hybrid magnetic levitation bearing structure for centrifugal kidney pumps. The magnetic bearing has the characteristics of small size, low power consumption and compact structure. It realizes the five degree of freedom (5-DOF) stable levitation of the rotor by actively controlling the axial single degree of freedom (1-DOF), aiming to replace the traditional rolling bearings in centrifugal kidney pumps. Firstly, the structure and working principle of the magnetic bearing are demonstrated. Secondly, the magnetic force properties of magnetic bearings were simulated and analyzed by finite element analysis method, and the magnetic bearing magnetic force model was derived based on the equivalent magnetic charge theory and magnetic circuit calculation theory. Finally, the magnetic bearing differential control system based on a pole assignment controller was designed, and the magnetic bearing prototype was trial-made, and its levitation performance was evaluated through simulation and experiment. Simulation and experimental results show that the magnetic bearing system has good levitation characteristics and low power consumption characteristics.