Magnetically Levitated Motor for Rotary Blood Pumps

Abstract

The noncontact rotary pumps under development for use as artificial heart pumps are highly efficient and can prevent thrombus formation. In these pumps magnetic bearings have been widely used to support the rotors to avoid any physical contact. The use of magnetic bearings, however, has led to requirements for the control of a large degree of freedom and for a separate driving motor. This paper introduces 2 types of levitated motors, each of which uses a combination of a rotary motor and a magnetic bearing. These motors are suitable for use in artificial blood pumps because they are small in size and can replace contact components. The radial type levitated motor has the merit of being small in size and capable of controlling the 2 degrees of freedom in the x and y directions. The axial type motor controls only one degree of freedom in the z direction. This paper also introduces the theoretical background of the functions of the motor and magnetic bearing. Experimental results of tests of the proposed motor show a great potential for its application in rotary blood pumps.

Proposal of a permanent magnet hybrid type axial magnetically levitated motor

“…In order to down size a maglev motor and to simplify the control system, several types of bearing-less motors (BfM) have been proposed and researched, such as a radial-BfM [3]- [4] and an axial-BfM [5]- [6]. To increase passive stability, the rotor shape should be a disk shape for radial-BfM or a long cylindrical shape for axial-BEM.…”

Vector control of an induction type axial gap combined motor-bearing

“…This requires a complex stator construction and results in the task of controlling both the rotation and the levitation being very difficult. Recently, radial combined motor-bearings have been applied to rotary blood pump [5]. However, simpler construction and less complex control system are desirable so as to miniaturize the rotor and to obtain reliability.…”

Applications of Permanent Maglev Bearing in Heart Pumps and Turbine Machine

“…Compared with the available passive magnetic bearing (Bearing A in Figure 1), which consists of two passive magnetic cylinders with same length but different outer and inner diameters and the smaller cylinder is located within the bigger one and both are magnetized same in axial direction [3], the Bearing B needs smaller axial occupation and has bigger axial magnetic bearing force; besides, the Bearing B showed the rotor maximal eccentric distances (maximum ED, ordinate) by different rotating speed (abscissa). It is clear, the maximum ED will go down to less than 0.15 mm when rpm is larger than 3250, that means the rotor has no contact with stator because the gap between rotor and stator is 0.15 mm.…”