Planar Litz Coil Equalizes Strand Lengths
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Solution Overview
Problem
Existing wireless power transfer systems using planar coils face challenges with skin depth and loop current issues due to the varying lengths of strands in multistrand coils, which can lead to inefficiencies in power transfer.
Innovation Solution
A planar Litz coil configuration is implemented using a plurality of strands arranged into first and second coil layers, where strands loop alternately between the layers to maintain equal lengths, reducing skin depth and loop current effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multistrand coils are used in planar wireless power transfer, then power transmission capability is improved, but skin depth and loop current issues arise due to varying strand lengths
Solution Approach 1:
The coil is divided into multiple discrete strands arranged in parallel, with each strand individually routed through layer transitions. This segmentation allows each strand to maintain equal effective length while collectively providing high power transmission capability, resolving the contradiction between power capability and loss reduction.
Solution Approach 2:
The patent transitions from a single-planar coil configuration to a three-dimensional multilayer structure. By routing strands through vertical transitions between layers, the design equalizes the effective length of each strand while maintaining high power transmission, thereby reducing skin depth and loop current effects that plague conventional planar coils.
2Ease of manufacture
If strands of different lengths are used in planar coils, then manufacturing simplicity is improved, but efficiency deteriorates due to skin depth and loop current effects
Solution Approach 1:
The strand routing incorporates dynamic transitions between layers at regular intervals, creating a structured pattern of layer crossings. This dynamic routing ensures that all strands experience equal effective lengths and similar electromagnetic environments, optimizing power transfer efficiency while maintaining manufacturing feasibility through standardized routing patterns.
Solution Approach 2:
The patent changes the geometric parameters of strand routing by introducing vertical layer transitions at specific intervals. This parameter modification equalizes the effective length of all strands, reducing variations that cause skin depth and loop current effects, thereby improving efficiency without significantly complicating the manufacturing process.
3Device complexity
If conventional planar coil configuration is used, then device complexity is reduced, but power transfer efficiency deteriorates due to varying strand lengths
Solution Approach 1:
The coil structure employs nested layers with strands systematically routed between them. Each layer contains parallel strands that transition to adjacent layers at regular intervals, creating a nested configuration that equalizes strand lengths. This nested structure achieves high efficiency while maintaining manageable complexity through systematic arrangement.
Solution Approach 2:
The strand routing follows a periodic pattern where strands transition between layers at regular spatial intervals. This periodic structure ensures all strands experience equivalent electromagnetic conditions and equal effective lengths, maximizing power transfer efficiency while maintaining regular, manufacturable geometry that does not excessively increase device complexity.
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 planar Litz coil configuration enhances the efficiency of wireless power transfer by minimizing skin depth and loop current issues, allowing for more effective and efficient power transmission.
Implementation Method 1
skin depth and loop current issues due to the varying lengths of strands in multistrand coils
Implementation Method 2
skin depth and loop current issues due to the varying lengths of strands in multistrand coils
Implementation Method 3
The transmission coil and the receiver coil can be brought close to one another to form a transformer that can facilitate inductive transmission of alternating current (AC) power
Data Source
AI summary
Structures, devices, and methods for wireless power transfer systems are described. A structure can include a plurality of strands arranged into a first coil layer and a second coil layer. The plurality of strands can be formed on a parallel path surrounding a center of the structure. The plurality of strands can extend away from the center on the first coil layer. The plurality of strands can extend towards the center on the second coil layer. For every fixed interval along a length of the structure, a first strand among the plurality of strands can be looped from the first coil layer to the second coil layer and a second strand among the plurality of strands can be looped from the second coil layer to the first coil layer.