Magnetic levitation performance of miniaturized magnetically levitated motor with 5-DOF active control

Abstract

Mechanical circulatory support (MCS) therapy plays a significant role in an alternative therapy of heart transplants for pediatric heart disease patients. However, continuous flow rotary MCS devices for pediatric patients are still undergoing development, and have not been clinically available technology. Technical difficulties, such as high durability, better blood compatibility and miniature device size, prevent the pediatric MCS devices development. In this study, a double stator axial gap maglev motor for pediatric MCS device has been developed. The maglev motor has two identical motor stators, and a levitated rotor impeller which is aligned between the stators. The levitated rotor impeller is fully suspended with 5-degrees of freedom (5-DOF) active control. A double stator mechanism enhances motor torque production. A miniaturized maglev motor was designed and developed based on FEM magnetic field analysis for use in implantable ventricular assist devices (VADs). The diameter and height of the developed maglev motor are 22 mm and 33 mm. This paper is an initial report on the magnetic levitation and rotation performance of the miniaturized maglev motor. The levitated rotor impeller was magnetically levitated and rotated with the 5-DOF active control. The oscillation amplitudes (x, y and z) and inclination angles (θx and θy) of the levitated rotor impeller were then evaluated in both air and water. The developed maglev motor achieved non-contact rotation up to 1600 rpm in air and 4500 rpm in water, respectively. The oscillation amplitudes and inclination angles were sufficiently suppressed in water due to fluid damping. After these experiments, a magnetic circuit of the maglev motor was modified in order to achieve further stable levitation. The developed maglev motor then indicated potential to achieve the practical use of maglev rotatory pediatric VAD.