Magnetic Actuator with Segmented Core for Suspension Stability
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Solution Overview
Problem
Magnetic suspension systems, such as active magnetic bearings, face instability due to increasing magnetic attractive force with decreasing air-gap, requiring active control and challenging design to avoid magnetic coupling between actuator elements while ensuring magnetic flux flows along ferromagnetic sheets without penetrating them.
Innovation Solution
The system employs actuator elements with a core structure comprising tooth sections and yoke sections, where the winding is wound around the center tooth section, and permanent magnets are placed between yoke sections, allowing magnetic flux produced by electric currents and permanent magnets to flow along ferromagnetic sheets without penetrating them, achieving flux decoupling and linear operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If permanent magnets are used to generate bias magnetic fluxes, then the magnetic suspension system can overcome static loads and linearize magnetic force dependence, but magnetic coupling between actuator elements occurs and control complexity increases
Solution Approach 1:
The core element is divided into multiple ferromagnetic sheets that are electrically insulated from each other. This segmentation prevents eddy currents and reduces magnetic coupling between adjacent actuator elements, as the magnetic flux paths are confined within each sheet rather than penetrating through the entire core structure.
Solution Approach 2:
The core element geometry is specifically designed with localized magnetic flux paths that guide the magnetic flux generated by permanent magnets to flow along the ferromagnetic sheets rather than penetrating through them. This local flux confinement reduces magnetic coupling between neighboring actuator elements while maintaining the bias flux function.
2Object-generated harmful factors
If the core element is designed to prevent magnetic flux penetration through ferromagnetic sheets, then eddy currents are avoided and flux decoupling is achieved, but the magnetic flux path design becomes more complex
Solution Approach 1:
The core element is constructed as a stack of thin ferromagnetic sheets separated by electrical insulation layers. This segmentation breaks the continuous magnetic flux path that would otherwise penetrate through the core, thereby preventing eddy currents while maintaining magnetic flux guidance along the sheets.
Solution Approach 2:
Electrical insulation layers are introduced as intermediary elements between adjacent ferromagnetic sheets. These insulation layers block the penetration of magnetic flux through the core thickness while allowing the flux to flow along the sheets, thus preventing eddy currents without significantly affecting the magnetic circuit functionality.
3Force
If the air-gap between magnet and object decreases, then magnetic attractive force increases, but system instability increases requiring more complex active control
Solution Approach 1:
Permanent magnets are pre-installed in the actuator elements to generate bias magnetic fluxes before the system operates. This preliminary action establishes a baseline magnetic force that counteracts static loads and linearizes the magnetic force characteristic, reducing the complexity of active control required to maintain stability.
Solution Approach 2:
The magnetic circuit design is optimized to maintain appropriate air-gap dimensions that balance magnetic attractive force and system stability. By carefully selecting the air-gap parameter, the system achieves sufficient magnetic force while avoiding the instability that occurs at excessively small gaps, reducing the burden on active control systems.
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 design stabilizes the magnetic suspension by preventing magnetic coupling and ensuring linear operation, enhancing control simplicity and reducing adverse effects from varying air-gaps and reluctance changes.
Implementation Method 1
a winding for conducting electric currents and a core element for conducting magnetic flux
Implementation Method 2
Some systems use permanent magnets to generate bias magnetic fluxes
Implementation Method 3
the core element is often a stack of ferromagnetic sheets
Implementation Method 4
the support at each direction is obtained by balancing attractive forces of two opposite acting magnets and other forces acting on an object to be suspended
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
A magnetic actuator comprises interconnected actuator elements (101-104) each comprising a core element (109) that comprises a center tooth section (110), side tooth sections (111, 112) on both sides of the center tooth section, and a yoke section (113) connecting the center and side tooth sections. Each actuator element further com- prises a winding (105) around the center tooth section. The magnetic actuator further comprises permanent magnets (114-117) in gaps between the yoke sections of adjacent ones of the core elements. The direction of magnetization of each of the permanent magnets is across the gap where the permanent magnet is located. As there are three teeth in each core element, decoupling is achieved so that magnetic flux caused by electric current in one actuator element does not significantly flow to other actuator elements. The permanent magnets generate bias magnetic fluxes which make the operation of the magnetic actuator more linear.