Planar Transformer Termination Loss Reduction
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Solution Overview
Problem
Planar transformers experience significant termination losses due to the proximity effect, where currents concentrate in narrow portions of the termination portions, leading to high power losses, especially at high frequencies, which is a major contributor to AC resistance.
Innovation Solution
The planar transformer configuration includes laterally offset gaps between termination portions and incorporates grounded portions adjacent to these gaps to spread current flow, reducing the proximity effect and minimizing termination losses.
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 to reduce device size, then the planar transformer achieves compact dimensions, 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 introduces a third dimension (depth into the page) by laterally offsetting the gaps between termination portions of different windings. Instead of having all gaps aligned in the same vertical plane, gaps are positioned at different lateral locations, which spreads the current distribution in the horizontal dimension and reduces the proximity effect while maintaining compact vertical stacking.
Solution Approach 2:
The patent segments the gaps between termination portions into different lateral positions across multiple circuit layers. By dividing the gap positions into offset groups rather than having them all aligned, the current paths are segmented into broader distributions, reducing current crowding at any single location and thereby reducing termination losses.
2Productivity
If high frequency switching is used to improve power supply efficiency, then power delivery is enhanced, but the skin depth decreases to only a few thousandths of an inch, causing termination loss to account for about 75% of total AC resistance
Solution Approach 1:
By offsetting gaps laterally in the horizontal dimension, the patent increases the effective current distribution area perpendicular to the skin depth direction. This dimensional change allows current to utilize more of the available conductor cross-section, partially compensating for the reduced skin depth at high frequencies and reducing termination losses.
Solution Approach 2:
The patent creates different local conditions for current flow by positioning gaps at different lateral locations. This ensures that current density is more evenly distributed across different regions of the termination portions, preventing localized current crowding and reducing overall termination losses at high frequencies.
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 configurations.
Implementation Method 1
Transformers are used in many applications to transfer electrical energy from one circuit to another through inductively coupled conductors or windings
Implementation Method 2
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
Data Source
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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.