Hybrid Magnetic Bearings for a Centrifugal Blood Pump

2007 ◽  
Author(s):  
Zhaohui Ren ◽  
Said Jahanmir ◽  
Hooshang Heshmat ◽  
James Walton
Keyword(s):  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Force Balance ◽  
Blood Pump ◽  
Axial Position ◽  
Circulatory Support ◽  
Radial Clearance ◽  
Axial Stiffness ◽  
Element Analysis ◽  
Centrifugal Blood Pump

A hybrid passive/active magnetic bearing system was designed for a rotary centrifugal blood pump being developed for long-term circulatory support for heart failure patients. This system consists of two axially spaced bearing combinations for complete magnetic levitation of the rotor using only a single-axis active control. Each bearing combination comprises a pair of axially oppositely polarized permanent magnet rings on the rotor and a similar pair in the stator housing for both radial support and axial bias flux, and an electromagnetic coil to actively control the rotor axial position. The design permits a relatively large radial clearance between rotor and stator, and provides sufficient radial/axial stiffness, active controllability over the desired axial travel of the rotor. The bearing characteristics were evaluated by electromagnetic finite element analysis. The prototype pump was fabricated and levitated using a PID controller with zero-force balance algorithm to stabilize the rotor in the thrust direction and minimize the power draw. The experimental results confirmed the efficacy of the proposed magnetic bearing design and associated control algorithm.

Magnetically Suspended Rotary Blood Pump (Keynote)

2005 ◽  
Author(s):  
Hooshang Heshmat ◽  
James F. Walton ◽  
Michael J. Tomaszewski ◽  
Said Jahanmir
Keyword(s):  
High Reliability ◽  
Medical Center ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
Active Magnetic Bearing ◽  
Blood Pump ◽  
Rotary Blood Pump ◽  
Centrifugal Blood Pump ◽  
Pump Rotor ◽  
Blood Flows

MiTiHeart™ LVAD is a rotary centrifugal blood pump with a hybrid passive/active magnetic bearing support system. It exhibits low power loss, low vibration, and high reliability under transient operating conditions. Unique features of the design include a simple and direct flow path for both main and washing blood flows, non-contact pump rotor, i.e., no rubbing surfaces, and relatively large clearances between the pump rotor and housing. The first prototype was constructed from medical grade polycarbonate. To reduce the possibility of thrombosis, the internally exposed surfaces were coated with a biocompatible polymer. Hemolysis test results showed a low normalized index of hemolysis of 0.01 mg/dL. An acute animal test was successfully completed at the Hershey Medical Center. During the test, the pump was implanted in a calf and operated in parallel with the heart. Following the acute test a chronic 200-hour implant study was completed. A second prototype was constructed using a titanium alloy for all blood contacting surfaces and incorporating a redundant hydrodynamic thrust bearing. This prototype was successfully evaluated in two chronic implant studies in a calf animal model for a total of 130 hours.

20315 Development of a Disposable Extracorporeal Centrifugal Blood Pump with Magnetic Bearing System

2009 ◽  
Vol 2009.15 (0) ◽  
pp. 213-214
Author(s):  
Wataru Hijikata ◽  
Pai Chi Nan ◽  
Tadahiko Shinshi ◽  
Akira Shimokohbe ◽  
Takeshi Someya ◽  
...  
Keyword(s):  
Magnetic Bearing ◽  
Blood Pump ◽  
Centrifugal Blood Pump ◽  
Bearing System

P-MB-05 A PM-EM TYPE MAGNETIC BEARING SYSTEM FOR A CENTRIFUGAL BLOOD PUMP

2003 ◽  
Vol 2003 (0) ◽  
pp. 377-378
Author(s):  
Tadahiko SHINSHI ◽  
Daisaku NISHINAKA ◽  
Junichi ASAMA ◽  
Hiroyuki KATAOKA ◽  
Setsuo TAKATANI ◽  
...  
Keyword(s):  
Magnetic Bearing ◽  
Blood Pump ◽  
Centrifugal Blood Pump ◽  
Bearing System

804 Effect of Thrust Bearing Gap on Hemolytic Property of a Hydrodynamically Levitated Centrifugal Blood Pump for Extracorporeal Circulatory Support

2012 ◽  
Vol 2012.20 (0) ◽  
pp. 213-214
Author(s):  
Tomotaka MURASHIGE ◽  
Ryo KOSAKA ◽  
Masahiro NISHIDA ◽  
Osamu MARUYAMA ◽  
Takashi YAMANE ◽  
...  
Keyword(s):  
Thrust Bearing ◽  
Blood Pump ◽  
Circulatory Support ◽  
Centrifugal Blood Pump ◽  
Hemolytic Property

Estimation of the radial force using a disturbance force observer for a magnetically levitated centrifugal blood pump

2009 ◽  
Vol 224 (7) ◽  
pp. 913-924 ◽  
Author(s):  
C N Pai ◽  
T Shinshi ◽  
A Shimokohbe
Keyword(s):  
Rotational Speed ◽  
Fluid Dynamic ◽  
Radial Force ◽  
Magnetic Bearing ◽  
Blood Pump ◽  
Working Fluid ◽  
Computational Fluid Dynamic Analysis ◽  
Centrifugal Blood Pump ◽  
Magnetically Levitated ◽  
Radial Thrust

Evaluation of the hydraulic forces in a magnetically levitated (maglev) centrifugal blood pump is important from the point of view of the magnetic bearing design. Direct measurement is difficult due to the absence of a rotor shaft, and computational fluid dynamic analysis demands considerable computational resource and time. To solve this problem, disturbance force observers were developed, using the radial controlled magnetic bearing of a centrifugal blood pump, to estimate the radial forces on the maglev impeller. In order to design the disturbance observer, the radial dynamic characteristics of a maglev impeller were evaluated under different working conditions. It was observed that the working fluid affects the additional mass and damping, while the rotational speed affects the damping and stiffness of the maglev system. Based on these results, disturbance force observers were designed and implemented. The designed disturbance force observers present a bandwidth of 45 Hz. In non-pulsatile conditions, the magnitude of the estimated radial thrust increases in proportion to the flowrate, and the rotational speed has little effect on the force direction. At 5 l/min against 100 mmHg, the estimated radial thrust is 0.95 N. In pulsatile conditions, this method was capable of estimating the pulsatile radial thrust with good response.

An Implantable Centrifugal Blood Pump for Long Term Circulatory Support

ASAIO Journal ◽  
1997 ◽  
Vol 43 (5) ◽  
pp. M691 ◽  
Author(s):  
KENJI YAMAZAKI ◽  
PHILIP LITWAK ◽  
ROBERT L. KORMOS ◽  
TOSHIO MORI ◽  
OSAMU TAGUSARI ◽  
...  
Keyword(s):  
Blood Pump ◽  
Circulatory Support ◽  
Centrifugal Blood Pump

Research About Eddy Effect and Dynamic Force of the Magnetic Thrust Bearing

2014 ◽  
Author(s):  
Xingnan Liu ◽  
Ni Mo ◽  
Guojun Yang ◽  
Zhengang Shi ◽  
Suyuan Yu
Keyword(s):  
Thrust Bearing ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Dynamic Force ◽  
Phase Lag ◽  
Direct Part ◽  
Element Analysis ◽  
Large Eddy ◽  
The Finite Element Analysis ◽  
Sinusoidal Current

The eddy effect of the magnetic thrust bearing (MTB) is researched by the finite element analysis (FEA). The active magnetic bearing (AMB) is an advanced bearing, used in HTR-PM. The alternating current in the bearing windings will decrease the electromagnetic force and cause phase lag, especially in the MTB which has no lamination structure. According to the calculation in this paper, simple sinusoidal current has large eddy effect. The force decreases obviously and the phase lag is large. However, the current containing direct part and sinusoidal part, which is closer to actual current, has less eddy effect. That is to say, because of the direct part in the current, the eddy effect of the sinusoidal part decreases.

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