Use of PM Bearings in Permanent Maglev Centrifugal Pumps for Stability Investigation

Abstract

It has been widely acknowledged that permanent maglev is unstable according to Earnshaw's theory (1839). The author has found, however, that this theorem is applicable only to a levitator in static state. For dynamic equilibrium, such as by a levitator in rotary pump, there has been no answer until now to the question whether permanent maglev can be stable. To investigate the feasibility of permanent maglev pumps, a passive magnetic(PM) bearing in common use(Bearing A) and a novel PM bearing developed by the author (Bearing B) were used separately in 3 prototypes of centrifugal pumps: axially driven centrifugal pump, radially driven biventricular assist pump and radially driven centrifugal pump. It exhibited that the PM bearings could achieve stable maglev in all centrifugal pumps, if the rotor had high enough speed and thus obtained a so-called gyro-effect, namely, a rotating body with high enough speed could maintain its rotation stably.