Bifilar Wireless Charging Coil Layout for Thin Qi-Efficient Power Transfer
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Solution Overview
Problem
Conventional wireless charging coils face challenges in achieving a balance between being thin, efficient, and Qi compliant, as they often compromise on material thickness to reduce resistance, leading to performance and manufacturing limitations.
Innovation Solution
A planar bifilar parallel-wound, series connected wireless charging coil design that increases magnetic coupling effectiveness by varying the coil's thickness and using a higher amount of conductive material within a given space, resulting in a thinner, more efficient coil with improved energy transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If material thickness is increased to lower resistance and improve efficiency, then energy transmission efficiency is improved, but device thickness increases and compactness deteriorates
Solution Approach 1:
The patent transitions from conventional planar coil structures to a three-dimensional bifilar parallel-wound configuration. This dimensional change allows conductive material to be arranged in multiple layers and directions, increasing the effective cross-sectional area for current flow without proportionally increasing the overall thickness. The bifilar structure with parallel windings creates overlapping conductive paths that reduce resistance while maintaining a compact profile.
Solution Approach 2:
The patent employs composite construction by combining multiple conductive material layers in a bifilar configuration. This composite approach integrates several thin conductive layers with ferrite core materials, creating a structure that achieves the equivalent electrical performance of a single thick conductor while maintaining thinner overall dimensions. The composite structure optimizes both electrical conductivity and magnetic coupling properties.
2Loss of energy
If more conductive material is used within a given space to increase density and reduce resistance, then efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the coil structure into segmented bifilar parallel windings rather than using a single continuous winding. This segmentation allows for modular construction where identical or similar coil segments can be manufactured separately and then assembled or stacked to achieve the desired total conductive material density. The segmented approach simplifies the manufacturing of each individual segment while enabling high overall material density through repetition and stacking.
3Reliability
If coil thickness is varied to optimize performance, then magnetic coupling effectiveness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent implements local quality variations in the bifilar parallel windings where different sections of the coil have optimized thickness and winding densities tailored to specific magnetic coupling requirements. This allows regions with higher magnetic field demands to have increased conductive material density, while other regions maintain thinner profiles. The local optimization approach achieves superior overall magnetic coupling effectiveness without requiring uniform high-precision thickness control across the entire coil structure.
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 solution achieves higher efficiency and magnetic field strength, enabling more effective energy transmission while maintaining a low profile and high fill factor, thus addressing the limitations of conventional coils.
Implementation Method 1
Wireless power transfer is the transfer of electrical power from a base station (transferring power) to a mobile device (consuming power) through electromagnetic induction (inductive power)
Implementation Method 2
Wireless power transfer is the transfer of electrical power from a base station (transferring power) to a mobile device (consuming power) through electromagnetic induction (inductive power) and/or resonant frequency method
Data Source
AI summary
A wireless charging coil assembly comprises a first stamped coil having a first trace, a second stamped coil having a second trace, and a film having a first side and a second side. The first stamped coil is adhered to the first side of the film and the second stamped coil is adhered to the second side of the film. At least a first portion of the first trace of the first stamped coil and at least a first portion of the second trace of the second stamped coil are electrically connected.