IMPELLER POSITION COMPENSATION USING FIELD ORIENTED CONTROL

摘要

A centrifugal pump system having an impeller rotating with first and second magnetic structures on opposite surfaces. A levitation magnetic structure is disposed at a first end of a pump housing having a levitating magnetic field for axially attracting the first magnetic structure. A multiphase magnetic stator at a second end of the pump housing generates a rotating magnetic field for axially and rotationally attracting the second magnetic structure. A commutator circuit provides a plurality of phase voltages to the stator. A sensing circuit determines respective phase currents. A controller calculates successive commanded values for the phase voltages in response to the determined phase currents and a variable commutation angle. The angle is selected to correspond to an axial attractive force of the stator that maintains a levitation of the impeller at a centered position within the pumping chamber.

主权项

1. A cardiac assist device for implanting in a patient, comprising:
a disc-shaped impeller rotating about an axis and having a first magnetic structure disposed at a first surface and a second magnetic structure disposed at a second surface; a pump housing defining a pumping chamber which receives the impeller, wherein the pump housing includes an inlet for receiving blood from a heart of the patient and an outlet for delivering blood to a circulatory vessel of the patient; a levitation magnetic structure disposed at a first end of the pump housing having a levitating magnetic field for axially attracting the first magnetic structure; a multiphase magnetic stator disposed at a second end of the pump housing for generating a rotating magnetic field for axially and rotationally attracting the second magnetic structure; a commutator circuit for providing a plurality of phase voltages to the stator; a sensing circuit determining respective phase currents flowing in response to the phase voltages; and a controller calculating successive commanded values for the phase voltages in response to a desired flow output through the outlet, the determined phase currents, and a variable commutation angle, wherein the angle is selected to correspond to an axial attractive force of the stator that maintains a levitation of the impeller at a centered position within the pumping chamber.