Impeller position compensation using field oriented control

• US 9,709,061 B2
• Filed: 06/03/2016
• Issued: 07/18/2017
• Est. Priority Date: 01/24/2013
• Status: Active Grant

• Current Assignee: TC1 LLC (Abbott Laboratories Incorporated)
• Original Assignee: TC1 LLC (Abbott Laboratories Incorporated)
• Inventors: Campau, Jeffrey H., Nanna, Jason C., Yanai, Masamichi
• Primary Examiner(s): Rodriguez, William H
• Assistant Examiner(s): BRUNJES, CHRISTOPHER J
• Application Number:
  US15/172,760
• Publication Number:
  US 20160281720A1
• Time in Patent Office: 410 Days
• Field of Search: 623 313, 623 314, 623 328, 604 401
• CPC Class Codes: A61M 2205/3303 Using a biosensor
• CPC Class Codes: A61M 2205/3507 with implanted devices, e.g. external control
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/232 Centrifugal pumps
• CPC Class Codes: A61M 60/419 the force acting on the blood contacting member being permanent magnetic, e.g. from a rotating magnetic coupling between driving and driven magnets
• CPC Class Codes: A61M 60/422 the force acting on the blood contacting member being electromagnetic, e.g. using canned motor pumps
• CPC Class Codes: A61M 60/538 Regulation using real-time blood pump operational parameter data, e.g. motor current
• CPC Class Codes: A61M 60/824 Hydrodynamic or fluid film bearings
• CPC Class Codes: F04B 35/04 the means being electric
• CPC Class Codes: F04D 13/024 a magnetic coupling
• CPC Class Codes: F04D 13/0666 the motor being of the plane gap type
• CPC Class Codes: F04D 15/0088 Testing machines
• CPC Class Codes: F04D 15/0094 Indicators of rotational movement
• CPC Class Codes: F04D 29/041 Axial thrust balancing
• CPC Class Codes: F04D 29/0473 for radial pumps
• CPC Class Codes: F04D 29/048 magnetic; electromagnetic
• CPC Class Codes: F04D 29/22 specially for centrifugal pumps
• CPC Class Codes: F04D 29/426 especially adapted for liquid pumps
• CPC Class Codes: F04D 29/428 Discharge tongues F04D17/04 takes precedence
• CPC Class Codes: F04D 7/04 the fluids being viscous or non-homogenous
• CPC Class Codes: H02P 6/18 : without separate position detecting elements

Abstract

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.

Claims

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 configured to calculate 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.

2. The device of claim 1 wherein the levitation magnetic structure is comprised of permanent magnet material and the levitating magnetic field is substantially constant.

3. The device of claim 1 wherein the angle for calculating the commanded values is determined in response to a phase current characteristic and a rotational speed of the impeller.

4. The device of claim 3 wherein the phase current characteristic is comprised of a peak current flowing in the stator during a predetermined sampling interval.

5. The device of claim 3 wherein the controller includes a lookup table storing predetermined values for the commutation angle corresponding to respective ranges of the phase current characteristic and the rotational speed.

6. A method of operating a centrifugal pump having an impeller rotating suspended within a pumping chamber of a pump housing, comprising the steps of:

providing a first magnetic structure disposed at a first surface of the impeller and a second magnetic structure disposed at a second surface of the impeller;

providing a levitating magnetic field from a first end of the pump housing for axially attracting the first magnetic structure;

providing 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;

supplying a plurality of phase voltages to the stator from an electrical commutator;

determining respective phase currents flowing in response to the phase voltages;

calculating, with a controller, 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.

7. The method of claim 6 wherein the levitating magnetic field is substantially constant.

8. The method of claim 6 wherein the angle for calculating the commanded values is determined in response to a phase current characteristic and a rotational speed of the impeller.

9. The method of claim 8 wherein the phase current characteristic is comprised of a peak current flowing in the stator during a predetermined sampling interval.

10. The method of claim 8 wherein the controller includes a lookup table storing predetermined values for the commutation angle corresponding to respective ranges of the phase current characteristic and the rotational speed.

11. The method of claim 6 wherein the centrifugal pump is implanted in a patient to supply an assistive blood flow, and wherein the desired flow output is comprised of a desired blood flow rate determined in response to physiological monitoring of the patient.