Planar Transformer Shielding Turns Reduce Capacitive Coupling
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Solution Overview
Problem
Planar transformers experience significant capacitive coupling between primary and secondary windings due to their large surface areas and small inter-plane distances, leading to safety and electromagnetic interference issues, and existing solutions require a separate shielding layer that increases costs.
Innovation Solution
Incorporating shielding turns on two layers that cover at least 50% of the winding window, acting as both electrostatic shields and auxiliary or compensation windings, to reduce capacitive coupling without the need for a conventional shielding layer, thereby reducing the number of layers and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional electrostatic shield is placed between the primary winding and the secondary winding, then the capacitive coupling is reduced, but the total number of layers increases and manufacturing cost increases
Solution Approach 1:
The patent combines the shielding function with the auxiliary/compensation winding function into a single structure. The third and fourth windings serve dual purposes: they provide capacitive coupling reduction between primary and secondary windings while simultaneously functioning as auxiliary or compensation windings. This merging eliminates the need for a separate dedicated shielding layer, reducing the total layer count while maintaining both shielding effectiveness and functional requirements.
Solution Approach 2:
The third and fourth windings are designed to perform multiple functions simultaneously. They act as electrostatic shields to reduce capacitive coupling between primary and secondary windings, while also serving as auxiliary windings for providing additional voltage outputs or compensation windings for reducing electromagnetic interference. This multi-functionality allows the transformer to achieve shielding without requiring additional dedicated layers.
2Object-affected harmful factors
If the shielding turn covers a large area, then the capacitive coupling reduction is more effective, but the space for other windings is reduced
Solution Approach 1:
The shielding turns are strategically positioned to cover critical areas where capacitive coupling occurs most significantly. Rather than uniformly shielding the entire winding window, the third and fourth windings are arranged to provide targeted shielding at key locations between the primary and secondary windings, achieving effective capacitive coupling reduction while preserving maximum space for other functional windings.
Solution Approach 2:
The patent employs partial shielding coverage rather than complete coverage of the winding window. The third and fourth windings provide shielding over sufficient areas to achieve the required capacitive coupling reduction, while leaving other areas open for auxiliary and compensation windings. This partial action approach balances shielding effectiveness with space utilization.
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
Effectively minimizes capacitive coupling between windings, reduces electromagnetic interference, and decreases manufacturing costs by eliminating the need for a separate shielding layer, while maintaining the structural integrity and functionality of the planar transformer.
Implementation Method 1
A known technique to reduce the capacitive coupling is to place an electrostatic shield between the primary winding and the secondary winding. The electrostatic shield, that can be a single turn winding, is formed on a single layer of the PCB and it essentially covers the entire winding window of the planar transformer.
Implementation Method 2
A planar transformer comprises an EI-core and a plurality of windings arranged concentrically with respect to each other on layers of a printed circuit board (PCB). The windings have a spiral pattern that is arranged to wind around an aperture provided in the layer.
Data Source
Figure 1~3
Figure 2
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AI summary
The present invention relates to a planar transformer that comprises a first winding (201, 413, 514) and a second winding (202, 415, 513), and a third winding (203, 416, 516) and a fourth winding (204, 417, 517) which are arranged between the first winding (201, 413, 514) and the second winding (202, 415, 513). In the planar transformer each of the third winding (203, 416, 516) and the fourth winding (204, 417, 517) comprises a shielding turn (208, 209, 418, 419, 518, 519) that covers at least 30 percent of a winding window of the planar transformer, said shielding turns (208, 209, 418, 419, 518, 519) being arranged in such a manner that the shielding turns (208, 209, 418, 419, 518, 519) together cover at least 50 percent of the winding window. The present invention also relates to a method for shielding windings (201, 202, 413, 415, 513, 514) in a planar transformer.