Planar Coil Structure for High-Frequency Transformer AC Loss Reduction
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Solution Overview
Problem
High-frequency transformers face increased AC loss and electromagnetic interference due to the skin effect and proximity effect in conventional continuous conductive planar coils, leading to reduced power density and reliability.
Innovation Solution
A continuous conductive planar coil structure with overlapping output terminals and a specific geometric configuration that reduces the area of AC current loops and minimizes the proximity effect, incorporating a first and second three-fourths circular path connected via a half-circular path to form a continuous conductive path between output terminals, with switches connected to a connecting plate for improved electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the switching frequency is increased to achieve high power density, then the volume of magnetic component is reduced, but the skin effect and proximity effect become more severe causing increased AC loss
Solution Approach 1:
The patent transitions from conventional three-dimensional winding coils to a two-dimensional planar coil structure. This dimensional change allows the coil to achieve compact volume while maintaining optimized current distribution paths that reduce the impact of skin effect and proximity effect, thereby reducing AC loss in high-frequency applications
Solution Approach 2:
The patent employs circular arc paths with specific radii (R1, R2, R3) in the planar coil design. These curved paths are strategically designed to maintain adequate spacing between adjacent current-carrying conductors, reducing magnetic coupling and proximity effect, while still achieving compact form factor for high power density
2Object-generated harmful factors
If the output terminals are placed close together to reduce loop area, then electromagnetic radiation is reduced, but current concentrates on the two sides proximate each other increasing power loss
Solution Approach 1:
The planar coil is divided into multiple segments with distinct functional zones: current input region, current output region, and intermediate regions with specific arc paths. This segmentation allows current to flow through optimized paths that maintain terminal proximity for reduced radiation while avoiding direct opposition that causes concentration and increased power loss
Solution Approach 2:
The patent employs asymmetric current paths with different arc radii (R1 for input, R2 for intermediate, R3 for output) and non-symmetric terminal positioning. This asymmetric design prevents direct face-to-face alignment of opposing currents that would cause concentration, while still maintaining compact loop area to reduce electromagnetic radiation
3Ease of manufacture
If conventional winding type coil is used, then manufacturing is simpler, but DC resistance is higher and heat-dissipating area is reduced
Solution Approach 1:
The patent replaces the mechanical winding process with a planar patterned conductor structure that can be manufactured using PCB or laminated techniques. This substitution maintains manufacturing simplicity while achieving superior electrical performance through optimized current paths and increased effective heat-dissipating surface area
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
Significantly reduces power loss and electromagnetic interference by minimizing the area of AC current loops and enhancing the distribution of current, thereby improving power density and reliability in high-frequency applications.
Implementation Method 1
there is an interval 10 between the two output terminals 11 and 12, so that there is the electromagnetic interference produced from the interval 10 to surroundings
Implementation Method 2
current concentrates on the two sides proximate each other owing to the coupling of electromagnetic fields therebetween, which is the proximity effect
Implementation Method 3
With the increasing frequency, the skin effect and the proximity effect of the AC current in a conductor are more severe
Data Source
AI summary
The present invention provides a continuous conductive planar coil structure. The continuous conductive planar coil structure includes a first output terminal, a second output terminal, a coil body and a projection plane parallel to the coil body, wherein a first projection on the projection plane is formed by the first output terminal, a second projection on the projection plane is formed by the second output terminal, and an overlapping portion is between the first projection and the second projection.