Design and control of hybrid magnetic bearings for maglev axial flow blood pump

Abstract

This paper introduces the development of hybrid magnetic bearings (HMBs) for a maglev axial flow blood pump. The design criteria for the radial, axial and current stiffness of the HMB are proposed and the HMB is accordingly designed through theoretical calculation, 3-Dimensional Finite Element Analysis (3-D FEA) and experimental verification. Based on the system identification result of the HMB, a proportional, integral, and derivative (PID) controller, low pass filter and lead compensator have been designed for the HMBs of the axial flow blood pump. Open and closed loop transfer functions of the system were determined and experimental results show that the developed maglev pump can spin stably in air with speeds up to 20,000 rpm and in water with speeds up to 9,000 rpm, which validate the design and control of HMBs of the maglev pump. The magnetic bearing system adequately supports the pump impeller and is well suited for this application