Abstract: A novel permanent maglev impeller blood pump has been developed recently, in which the impeller and the rotor are levitated by passive magnetic and hydrodynamic bearings, therefore neither position measurement nor feedback control is necessary. Nevertheless, the authors detect the position of the impeller with Hall sensors in order to verify whether the impeller is actually levitated and to certify which factors affect the stability of the levitation. The results demonstrate that the higher the rotating speed and the flow rate, the more stable the equilibrium of the levitation; and the higher the viscosity of the fluid, the more stable the suspension of the rotor; besides, it seems that the gap between the rotor and the stator has an optimal value about 1% of the rotor diameter, while the maximal gap by hydrodynamic bearing alone is only 0.1% of the rotor diameter.

Key words: Mechanical wear, Permanent maglev, Rotary machine, Rotor position detection