Air-Gap Magnetic Shielding Structure for Lower EMI and AC Loss
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Solution Overview
Problem
Conventional magnetic components suffer from air gap fringing fields that induce AC losses, EMI, and require complex redesigns or increased component volume to mitigate these issues, leading to inefficiencies and heat generation.
Innovation Solution
A magnetic component with a shielding device comprising a holding unit and shield members made of insulating material, attached to the magnetic core and windings, which shields fringing fields without requiring complex redesigns, using a holding unit that can be easily assembled and attached to various core designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If copper windings surround the air gap to shield fringing fields, then EMI is reduced, but AC losses increase significantly
Solution Approach 1:
The patent changes the material parameter of the shielding structure from conductive copper to non-conductive plastic, fundamentally altering how the shield interacts with electromagnetic fields. This eliminates eddy current losses while maintaining shielding effectiveness through the plastic material's dielectric properties and structural design.
Solution Approach 2:
The patent uses composite construction by integrating the shielding function into the plastic housing material itself, rather than using separate copper shields. The plastic matrix combined with appropriate fillers or structural design creates an effective electromagnetic shield without the drawbacks of pure copper constructions.
2Loss of energy
If litz wires are used to reduce AC copper losses, then energy efficiency improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the shielding function from the copper winding structure entirely and relocates it to the plastic housing. This eliminates the need for specialized litz wires and their complex manufacturing processes, while maintaining the essential function of reducing AC losses.
3Loss of energy
If the winding is distanced from the air gap to reduce AC losses, then energy efficiency improves, but component volume increases
Solution Approach 1:
The plastic housing acts as an intermediary structure that simultaneously serves as the shield and maintains optimal winding positioning. This mediator structure reduces AC losses without requiring increased component volume, as the shielding function is integrated into the existing housing space.
4Object-affected harmful factors
If magnetic core components are redesigned to include integral demagnetization shields, then shielding effectiveness improves, but manufacturing complexity increases
Solution Approach 1:
The patent separates the shielding function from the magnetic core design itself and places it in the plastic housing structure. This segmentation allows the magnetic core to remain simple and unchanged, while the housing independently provides the necessary shielding through its design.
5Object-affected harmful factors
If bulk magnetic shielding structures are used, then fringing field shielding improves, but heat generation increases due to magnetic short circuits
Solution Approach 1:
The patent changes the material parameter from magnetic (prone to short circuits) to non-magnetic plastic, eliminating the heat generation issue entirely. The plastic housing provides shielding through its dielectric properties and structural configuration rather than magnetic properties.
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
The solution effectively shields fringing fields, reducing AC losses, minimizing EMI, and maintaining power density while simplifying assembly and reducing material and labor costs.
Implementation Method 1
a pair of shield members are provided on sides of an air gap so as to sandwich the air gap... the shield members are formed of a non-magnetic material having conductivity
Implementation Method 2
the shield members are formed of a non-magnetic material having conductivity. Therefore, the shield members described therein are not suitable for shielding magnetic fringing fields of the air gap. Further, eddy currents generated in these shield members greatly increase the heat generation of such a magnetic component
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The invention concerns a magnetic component (1), comprising at least one magnetic core (2), wherein at least one gap (3) is formed between end surfaces (4), especially opposing end surfaces (4), of the magnetic core(s) (2); at least one electrical winding (5) surrounding at least a part of the at least one magnetic core (2); and a shielding device (10) for shielding fringing fields of the at least one gap (3), wherein the shielding device (10) comprises: a holding unit (11) attached to the at least one magnetic core (2) and/or to the at least one electrical winding (5) in a periphery of the at least one gap (3); and at least one shield member (12) attached to the holding unit (11); wherein the at least one shield member (12) is configured to shield gap-fringing fields in the periphery of the gap (3).