Resonator Coil Topology for Large-Gap Wireless Power Efficiency
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Solution Overview
Problem
Current resonator coil designs for large gap wireless power transfer systems suffer from low efficiency and poor thermal performance, particularly at extended ranges, leading to energy losses and overheating due to non-uniform magnetic field distribution and weak coupling between transmitter and receiver coils.
Innovation Solution
The design incorporates a dielectric substrate with conductive traces forming a coil topology featuring non-uniform turn dimensions and a capacitor arrangement, including series and shunt capacitors, to optimize resonant frequency, input impedance, and efficiency, minimizing magnetic field variance over a target area and enhancing coil-to-coil and system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional resonator coil designs are used for large gap WPT, then the system can operate over extended ranges, but efficiency drops rapidly and thermal performance deteriorates
Solution Approach 1:
The patent applies local quality by implementing non-uniform turn dimensions within the coil structure. Different sections of the coil have differently sized turns, creating localized variations in magnetic field strength. This non-uniform distribution optimizes the magnetic field across the entire gap distance, maintaining higher efficiency at extended ranges by concentrating field strength where needed rather than using a uniform coil design.
Solution Approach 2:
The patent employs parameter changes by systematically varying the turn dimensions (radius, width, spacing) of the coil segments. By changing these geometric parameters across different turns, the coil achieves optimized magnetic coupling over large gaps. The capacitor values are also adjusted to tune the resonant frequency and impedance matching, further enhancing efficiency at extended operating ranges.
2Length of stationary object
If conventional resonator coil designs are used for large gap WPT, then the system can transfer power over extended ranges, but thermal performance becomes poor due to non-uniform magnetic field distribution
Solution Approach 1:
The non-uniform turn dimensions create localized magnetic field optimization that distributes power transfer more evenly across the coil structure. This prevents concentration of excessive magnetic field strength in single areas, thereby reducing hot spots and improving overall thermal performance during extended gap operation.
Solution Approach 2:
The patent creates a more dynamic and adaptable magnetic field distribution through varied turn dimensions. This dynamic field distribution adjusts the magnetic coupling characteristics across different spatial zones, enabling better thermal management by avoiding static, concentrated field patterns that lead to overheating at extended ranges.
3Loss of energy
If resonator coils are optimized for a specific gap distance, then efficiency is maximized at that distance, but efficiency falls off rapidly when the receiver coil is moved away
Solution Approach 1:
The patent achieves universality by designing a coil structure that performs effectively across multiple gap distances rather than being optimized for a single distance. The non-uniform turn dimensions enable the coil to maintain efficient magnetic coupling whether the receiver is positioned close to or far from the transmitter, providing versatile operation across a range of gap distances without significant efficiency loss.
Solution Approach 2:
The varied geometric parameters of different turns create a multi-functional coil that adapts to different operating conditions. By incorporating turns of different sizes and spacings, the coil can effectively couple with receiver coils at various distances, maintaining efficiency across a broader operational range rather than being constrained to a single optimized gap distance.
4Device complexity
If lower efficiency coils are used, then system complexity can be reduced, but energy losses increase and cause overheating
Solution Approach 1:
The patent reduces heat generation through local quality optimization rather than requiring complex active cooling or control systems. By strategically varying turn dimensions to create optimized local magnetic field distributions, the design achieves higher efficiency and reduces energy losses that would otherwise convert to harmful heat, thereby addressing thermal issues through geometric optimization rather than added 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
This approach results in improved coil-to-coil efficiency, reduced energy losses, and enhanced thermal performance, enabling efficient wireless power transfer over larger gaps, such as through-wall applications, with efficiencies exceeding 90% and extended power ranges.
Implementation Method 1
resonant-based power sources inject an oscillating current into a highly resonant coil to create an oscillating electromagnetic field
Implementation Method 2
A second coil with the same resonant frequency receives power from the electromagnetic field and converts it back into an electrical current
Implementation Method 3
two coils, tuned to resonate at the same frequency
Data Source
AI summary
High efficiency resonator coils for large gap resonant wireless power transfer (WPT), and a coil design methodology are disclosed. Resonator coils comprise a coil topology defined by coil parameters in which turn dimensions, such as trace widths and spacings of each turn, are configured to reduce or minimize a variance of the z component of magnetic field, over an area of a charging plane at a specified distance, or distance range, from the coil. A Tx resonator coil comprises a capacitor arrangement of tuning and network-matching capacitors for improved coil-to-coil efficiency and end-to-end WPT system performance, e.g. for applications such as through-wall WPT, in the range of tens of watts to at least hundreds of watts. Planar resonator coil topologies are compatible with fabrication using low cost PCB technology, e.g. with multi-layer metal, to reduce losses and improve thermal performance.