title: Modeling and control of a magnetic bearing system for the magnetically suspended centrifugal blood pump.
abstract: We have developed a centrifugal blood pump with a magnetically suspended impeller to reduce the hemolysis level for long-term use. The main advance we have made was simplifying the traditional 5 axes controlled magnetic bearing system, since the total device should ultimately be small enough to implant into a human body. A simplified magnetic bearing system with only 3 actively controlled axes was designed to levitate the impeller. The state equations of the magnetic bearing plant were established using Lagrange's methods, and using the results, a linear quadratic optimal controller was designed to regulate the position of the impeller. Flow rate and differential pressure of 5L/min and 300 mmHg, respectively at a motor speed of 2750 rpm was achieved from a mock circulation setup. These results show satisfactory performance as a cardiopulmonary bypass device. The lowering of pumping efficiency as the clearance between the impeller and pump housing increased was negligible. Thus for power efficiency, the smallest gap not leading to a hemolysis level rise can be determined as a feasible operation clearance.
authors.affiliation: Interdisciplinary Program, Graduate School, Seoul National University, Korea.
authors.forename: H
authors.initials: H
authors.lastname: Kim
authors.forename: H C
authors.initials: HC
authors.lastname: Kim
mesh_terms: D000465:Algorithms; D002498:Centrifugation; D004867:Equipment Design; D006353:Heart-Assist Devices; D006461:Hemolysis; D006801:Humans; D008280:Magnetics; D012212:Rheology