Development of Magnetic Bearing System for a New Third-Generation Blood Pump

Jung Joo Lee, Chi Bum Ahn, Jaesoon Choi, Jun Woo Park, Seung Joon Song, Kyung Sun

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

A magnetic bearing system is a crucial component in a third-generation blood pump, particularly when we consider aspects such as system durability and blood compatibility. Many factors such as efficiency, occupying volume, hemodynamic stability in the flow path, mechanical stability, and stiffness need to be considered for the use of a magnetic bearing system in a third-generation blood pump, and a number of studies have been conducted to develop novel magnetic bearing design for better handling of these factors. In this study, we developed and evaluated a new magnetic bearing system having a motor for a new third-generation blood pump. This magnetic bearing system consists of a magnetic levitation compartment and a brushless direct current (BLDC) motor compartment. The active-control degree of freedom is one; this control is used for controlling the levitation in the axial direction. The levitation in the radial direction has a passive magnetic levitation structure. In order to improve the system efficiency, we separated the magnetic circuit for axial levitation by using a magnetic circuit for motor drive. Each magnetic circuit in the bearing system was designed to have a minimum gap by placing mechanical parts, such as the impeller blades, outside the circuit. A custom-designed noncontact gap sensor was used for minimizing the system volume. We fabricated an experimental prototype of the proposed magnetic bearing system and evaluated its performance by a control system using the Matlab xPC Target system. The noncontact gap sensor was an eddy current gap sensor with an outer diameter of 2.38mm, thickness of 0.88mm, and resolution of 5μm. The BLDC motor compartment was designed to have an outer diameter of 20mm, length of 28.75mm, and power of 4.5W. It exhibited a torque of 8.6mNm at 5000rpm. The entire bearing system, including the motor and the sensor, had an outer diameter of 22mm and a length of 97mm. The prototype exhibited sufficient levitation performance in the stop state and the rotation state with a gap of 0.2mm between the rotor and the stator. The system had a steady position error of 0.01μm in the stop state and a position error of 0.02μm at a rotational speed of 5000rpm; the current consumption rates were 0.15A and 0.17A in the stop state and the rotation state, respectively. In summary, we developed and evaluated a unique magnetic bearing system with an integrated motor. We believe that our design will be an important basis for the further development of the design of an entire third-generation blood pump system.

Original languageEnglish
Pages (from-to)1082-1094
Number of pages13
JournalArtificial Organs
Volume35
Issue number11
DOIs
Publication statusPublished - 2011 Nov 1

Keywords

  • Axial-flow pump
  • Magnetic bearing
  • Ventricular assist device

ASJC Scopus subject areas

  • Bioengineering
  • Medicine (miscellaneous)
  • Biomaterials
  • Biomedical Engineering

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