Planar Transformer Offset Gaps Reduce Termination Losses
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Solution Overview
Problem
Planar transformers experience significant termination losses due to the proximity effect, where currents crowd together in narrow portions of the termination portions, leading to high power losses, especially at high frequencies, which is a challenge in compact electronic devices.
Innovation Solution
The planar transformer design includes a stack of circuit layers with gaps between termination portions that are laterally offset or have a grounded portion adjacent to the gaps, which spreads the current flow and reduces termination losses by mitigating the proximity effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the first and second termination portions are disposed close to one another with a narrow gap, then the planar transformer achieves a compact structure, but the proximity effect causes currents to crowd together and flow only in narrow portions, resulting in significant termination losses
Solution Approach 1:
The patent offsets the gaps between termination portions in the first and second circuit layers laterally in a direction perpendicular to the stacking direction. This dimensional shift prevents the gaps from aligning vertically, thereby spreading the current flow path and reducing the proximity effect while maintaining the compact planar structure.
Solution Approach 2:
The patent introduces a grounded portion in the third circuit layer that is laterally aligned with the gaps in the first and second circuit layers. This grounded portion acts as an intermediary that shields the gaps from each other, reducing the mutual electromagnetic influence and mitigating the proximity effect between the termination portions.
2Device complexity
If the gaps between termination portions are narrow, then the transformer windings are compact, but the current flows only in narrow portions extending approximately one skin-depth from the edges, causing high power losses
Solution Approach 1:
By laterally offsetting the gaps between termination portions in different circuit layers, the patent extends the effective current flow path in the lateral dimension. This prevents current confinement to narrow vertical sections and distributes the current across a larger effective area, reducing power losses while maintaining compact winding structures.
Solution Approach 2:
The grounded portion positioned between the gaps serves as a shielding intermediary that reduces the electromagnetic coupling between adjacent termination portions. This allows the current to distribute more evenly across the termination portions without being constrained by the narrow gap regions, thereby reducing power losses.
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 configuration significantly reduces termination losses by spreading current flow through a larger portion of the termination portions, resulting in a power loss reduction of more than three times compared to traditional designs.
Implementation Method 1
When the first and second termination portions are disposed close to one another and are separated by a narrow gap, they may be susceptible to the proximity effect. The proximity effect causes currents flowing through the closely-spaced first and second termination portions to crowd together and flow only in the narrow portions of the first and second termination portions that are closest to the gap.
Implementation Method 2
The narrow portion may extend approximately one 'skin-depth' from the edges of the first and second termination portions that are disposed adjacent to the gap. When a power supply providing power to the planar transformer switches at a high frequency, e.g., in the order of 100 s of kHz, the 'skin depth' of the first and second termination portions may be only a few thousandths of an inch.
Implementation Method 3
Transformers are used in many applications to transfer electrical energy from one circuit to another through inductively coupled conductors or windings.
Data Source
AI summary
The present disclosure relates to planar transformers including a plurality of circuit layers that are configured to reduce termination losses on at least one of the plurality of circuit layers. The plurality of circuit layers are stacked together in a first direction and include at least first and second circuit layers. The first and second circuit layers each include an electrically conductive trace forming at least one winding having a first termination portion and a second termination portion that are separated by a gap. The gaps of the first and second circuit layers are offset relative to each other in a second direction different from the first direction. The plurality of circuit layers may further include a third circuit layer, which includes an electrically conductive trace having a grounded portion that is disposed adjacent to at least one of the gaps of the first and second circuit layers.