TRx Coil Trace Width Optimization for Wireless Power Transfer
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Solution Overview
Problem
Current wireless power systems face inefficiencies due to the conflicting geometric constraints of transmit and receive coils, leading to poor performance when a single coil is required to serve both functions, with issues such as high coil resistance, inappropriate mutual and self-inductance, and incompatibility with other coils like NFC or PMA.
Innovation Solution
The development of a transmit/receive (TRx) coil design that optimizes trace widths and ferrite core thickness, allowing for efficient operation in both transmit and receive modes by varying the width and number of fingers in each turn, and using shared capacitors and optimized operating frequencies to enhance magnetic flux and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single coil is designed to serve both transmit and receive functions, then device integration is improved, but coil resistance increases and performance deteriorates
Solution Approach 1:
The coil is divided into multiple segments or sections, each optimized for specific functions. The coil structure includes multiple turns with varying trace widths where inner turns have narrower widths and outer turns have wider widths, creating segmented functional zones that reduce overall resistance while maintaining dual functionality.
Solution Approach 2:
Different portions of the coil are given different local properties - inner turns have narrower trace widths optimized for transmit function while outer turns have wider trace widths optimized for receive function. This local differentiation allows each section to perform its function efficiently, reducing overall energy loss.
2Loss of energy
If trace width is increased to reduce resistance, then coil resistance decreases, but mutual inductance becomes inappropriate
Solution Approach 1:
The trace width varies locally throughout the coil structure - narrower in inner turns and wider in outer turns. This local quality variation allows the coil to achieve low resistance through wider outer traces while maintaining appropriate mutual inductance through narrower inner traces that are closer to the ferrite core.
Solution Approach 2:
The trace width parameter is changed progressively from inner to outer turns. This parameter variation allows optimization of resistance without compromising mutual inductance, as the effective inductance is dominated by inner turns while resistance is significantly contributed by outer turns.
3Reliability
If ferrite core thickness is increased to enhance magnetic flux, then magnetic flux increases, but device thickness increases
Solution Approach 1:
The design uses a composite structure combining ferrite core with optimized copper trace patterns. The ferrite core provides magnetic flux concentration while the varying trace width pattern in the coil windings enhances the magnetic coupling efficiency, achieving high magnetic flux with reduced core thickness requirements.
Solution Approach 2:
Instead of increasing ferrite core thickness, the design changes the trace width parameter of the coil windings. By optimizing the trace widths to vary from inner to outer turns, the magnetic flux efficiency is improved without increasing the device thickness.
4Productivity
If coil geometry is optimized for transmit function, then transmit efficiency is improved, but receive compatibility deteriorates
Solution Approach 1:
The coil is segmented into inner and outer regions with different geometric properties. Inner turns have narrower widths optimized for transmit efficiency, while outer turns have wider widths optimized for receive compatibility. This segmentation allows the single coil to perform both functions effectively.
Solution Approach 2:
The coil structure is designed with universal functionality to serve both transmit and receive modes. By incorporating varying trace widths across different portions of the coil, the structure achieves multi-functionality, performing transmit operations with narrow inner traces and receive operations with wide outer traces.
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 design achieves improved efficiency and compatibility with other wireless standards by reducing coil resistance and enhancing mutual inductance, allowing for effective wireless power transfer in both transmit and receive modes while maintaining a compact form factor.
Implementation Method 1
a transmitter driving a transmit coil and a receiver with a receiver coil placed proximate to the transmit coil. The receiver coil receives the wireless power generated by the transmit coil
Implementation Method 2
optimization of wireless power coil designs (transmit coils and receive coils) and coil designs that can be used as both transmit and a receive coil (a TRx coil)
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
In accordance with embodiments of the present invention, a coil design for the transmission of wireless power. In some embodiments, the coil can include a winding with one or more turns of conductive traces mounted on a substrate, wherein the one or more turns include characteristics that enhance operation of the coil. In some embodiments, the winding includes a transmit coil and a receive coil, each coupled to terminals that provide for a transmit functionality and a receive functionality. In some embodiments, the traces are varied in width and/or thickness in order to optimize the inductance and the coil resistance. In some embodiments, parameters of a control circuit coupled to the coil to affect a transmit functionality or a receive functionality can be optimized.