Coaxial Inductor Structure for Low Leakage and EMI Control
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Solution Overview
Problem
Conventional inductor devices face challenges in achieving low leakage inductance and magnetizing inductance values required for high-frequency applications, while also ensuring electromagnetic interference (EMI) compliance through a fully encapsulated magnetic core design without air-gaps.
Innovation Solution
The proposed inductor device features a first and second electrically conductive path with a spacer material for electrical isolation, surrounded by a magnetically permeable material with higher permeability than the spacer, allowing for controlled magnetic flux distribution and reduced leakage and magnetizing inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional inductor designs are used, then manufacturing and assembly are simpler, but leakage inductance and magnetizing inductance values are too high for high-frequency applications
Solution Approach 1:
The patent implements a coaxial transformer structure where the secondary winding is nested inside the primary winding, forming a concentric arrangement. This nesting configuration enables precise control of leakage and magnetizing inductance by adjusting the radial spacing between windings, while maintaining a compact cylindrical form factor suitable for high-frequency applications.
Solution Approach 2:
The patent applies different magnetic materials with specific permeability values to different regions of the transformer core. By selecting materials with appropriate magnetic properties for the core and shield regions, the design achieves optimized inductance characteristics and EMI compliance without requiring complex overall structural changes.
2Manufacturing precision
If air-gaps are introduced in magnetic core design, then magnetizing inductance can be reduced, but electromagnetic interference compliance and magnetic flux leakage worsen
Solution Approach 1:
The patent controls magnetizing inductance by adjusting the physical dimensions of the magnetic core and the radial spacing between windings, rather than introducing air-gaps. By changing geometric parameters such as core radius and winding separation distance, the design achieves the required low magnetizing inductance while maintaining continuous magnetic flux paths that prevent EMI and flux leakage.
Solution Approach 2:
The patent introduces a magnetic shield as an intermediary component between the windings and the external environment. This shield confines the magnetic flux within the transformer structure, preventing magnetic flux leakage and EMI while allowing the core geometry to be optimized for low magnetizing inductance.
3Object-affected harmful factors
If fully encapsulated magnetic core design is used for EMI compliance, then electromagnetic interference is reduced, but leakage inductance and magnetizing inductance control becomes more difficult
Solution Approach 1:
The patent optimizes the magnetic properties of specific core regions by using materials with different permeability values in different locations. The core material is selected to provide both EMI shielding and the appropriate magnetic coupling between windings, while the shield material is optimized for flux confinement. This localized material optimization enables simultaneous achievement of EMI compliance and precise inductance control.
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 achieves virtually zero leakage inductance and low magnetizing inductance, enabling high-frequency power transfers and EMI compliance, suitable for applications like adapters and flyback converters.
Implementation Method 1
The second material has a substantially higher magnetic permeability than the first material. In such an instance, current flowing through the first electrically conductive path generates magnetic flux. A density of the generated magnetic flux in the second material is substantially higher than the density of magnetic flux in the first material.
Implementation Method 2
Via first material (such as spacer or isolator material), the first electrically conductive path is spaced with respect to the second electrically conductive path of the inductor device. The first material causes the first electrically conductive path to be electrically isolated from the second electrically conductive path in the inductor device.
Data Source
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AI summary
According to one configuration, an inductor device includes a first electrically conductive path (131); a second electrically conductive path (132), the first electrically conductive path electrically isolated from the second electrically conductive path; first material (141), the first material operative to space the first electrically conductive path with respect to the second electrically conductive path; and second material (142). The second material has a substantially higher magnetic permeability than the first material. An assembly of the first electrically conductive path, the second electrically conductive path, and the first material resides in a core of the second material.