Centrifugal Pump Impeller Position Compensation Using Field Oriented Control
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Solution Overview
Problem
Existing centrifugal pumping devices for circulatory assist systems face challenges in maintaining a centered position of the magnetically-levitated impeller without active control, which is essential to prevent hemolysis and thrombosis, while also minimizing system complexity and size.
Innovation Solution
A centrifugal pump system with a disc-shaped impeller and a magnetic structure that uses a commutator circuit and sensing circuit to adjust the commutation angle of the multiphase magnetic stator, maintaining the impeller's centered position within the pumping chamber by balancing hydrodynamic and magnetic forces, reducing the need for active levitation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active monitoring and control of impeller position is employed by adjusting the stationary magnetic field, then the impeller centered position is maintained, but position sensors and adjustable magnetic sources occupy significant space and add system complexity
Solution Approach 1:
The impeller maintains its own centered position through self-centering forces generated by the interaction between its magnetic structures and the stator's magnetic field. The upper and lower magnetic structures on the impeller interact with the stator to automatically center the impeller without requiring external position sensors or adjustable magnetic sources, making the system self-regulating.
Solution Approach 2:
The patent removes the need for position sensors and adjustable magnetic sources from the system. By designing the magnetic field interaction to inherently produce self-centering forces, the complex active control components are extracted and eliminated, simplifying the overall system while maintaining position stability.
2Reliability
If active monitoring and control of impeller position is employed, then the impeller centered position is maintained, but position sensors and adjustable magnetic sources occupy significant space
Solution Approach 1:
The patent removes the need for position sensors and adjustable magnetic sources from the system. By designing the magnetic field interaction to inherently produce self-centering forces, the complex active control components are extracted and eliminated, simplifying the overall system while maintaining position stability.
Solution Approach 2:
The stator serves multiple functions: it generates the rotating magnetic field for impeller rotation and simultaneously provides the magnetic field interaction that produces self-centering forces. This multi-functionality eliminates the need for separate position control components, reducing the overall pump volume.
3Ease of manufacture
If the impeller is magnetically levitated, then contactless rotation is obtained and the pumping chamber can be more completely isolated, but maintaining proper spacing requires active control that adds complexity
Solution Approach 1:
The magnetic levitation system is designed to automatically maintain proper impeller spacing through self-centering forces. The interaction between the impeller's magnetic structures and the stator's magnetic field inherently keeps the impeller centered, eliminating the need for complex active control systems while maintaining the benefits of magnetic levitation and chamber isolation.
4Ease of manufacture
If the impeller is magnetically levitated, then contactless rotation is obtained, but maintaining proper spacing from chamber walls requires active control
Solution Approach 1:
The magnetic levitation system is designed to automatically maintain proper impeller spacing through self-centering forces. The interaction between the impeller's magnetic structures and the stator's magnetic field inherently keeps the impeller centered, eliminating the need for complex active control systems while maintaining the benefits of magnetic levitation and chamber isolation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively maintains the impeller's centered position, reducing shear stress and flow stasis, thus minimizing hemolysis and thrombosis risks, while achieving a compact design and reducing system complexity.
Implementation Method 1
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
Implementation Method 2
A levitation magnetic structure is disposed at a first end of the pump housing having a levitating magnetic field for axially attracting the first magnetic structure
Implementation Method 3
Features (not shown) may also be formed in the walls of the pumping chamber to produce a hydrodynamic bearing wherein forces from the circulating fluid also tend to center the impeller
Data Source
AI summary
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.