Wheel Coils Enhance Magnetic Coupling for Wireless Power
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Solution Overview
Problem
Current wireless power transfer technologies face inefficiencies due to non-uniform magnetic flux patterns between transmitter and receiver coils, limiting power transfer to around 5 Watts over short distances, necessitating improvements in magnetic coupling for enhanced power transfer efficiency.
Innovation Solution
The use of a wheel coil structure with a magnetic core and solenoidal coils wound around spoke portions, which enhances magnetic coupling by creating a more uniform flux pattern, allowing for increased power transfer efficiency between wireless power transmitter and receiver coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single spiral receiver coil is placed in close proximity to a single spiral transmitter coil, then the device complexity is simple, but the magnetic coupling efficiency is poor resulting in non-uniform flux pattern
Solution Approach 1:
The wheel coil structure divides the magnetic core into multiple spoke portions (typically 3-6 spokes) arranged radially around a central axis. Each spoke portion acts as an independent magnetic flux path, segmenting the magnetic circuit to create multiple flux channels between transmitter and receiver coils, thereby improving magnetic coupling efficiency and flux uniformity.
Solution Approach 2:
The wheel coil structure transitions from a planar spiral coil configuration to a three-dimensional radial spoke configuration. The magnetic flux paths extend radially outward from the central axis through multiple spokes, adding a dimensional aspect that enhances flux distribution uniformity and coupling efficiency compared to traditional planar designs.
2Device complexity
If near-field WPT technology operates at 100-400 kHz frequency, then the device complexity is low, but the power transfer capability is limited to around 5 Watts
Solution Approach 1:
The wheel coil structure modifies key magnetic circuit parameters including increasing the effective magnetic path area through radial spoke configuration, optimizing magnetic flux density distribution, and enhancing inductance values. These parameter changes enable the system to transfer higher power levels while maintaining operation in the 100-400 kHz frequency range without requiring complex system modifications.
3Manufacturing precision
If the magnetic flux pattern between transmitter and receiver coils is non-uniform, then the manufacturing precision requirements are low, but the power transfer efficiency is poor
Solution Approach 1:
By segmenting the magnetic core into multiple radial spokes, the structure creates multiple independent flux channels that naturally distribute magnetic flux more uniformly across the air gap between transmitter and receiver coils. This segmentation approach achieves flux uniformity through geometric configuration rather than requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The wheel coil structure employs composite magnetic core designs that may combine different magnetic materials with varying permeability characteristics in different spoke portions. This allows optimization of flux distribution across the core structure, achieving uniform flux patterns that enhance power transfer efficiency without demanding ultra-precise manufacturing.
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 improves the efficiency of wireless power transfer by optimizing magnetic coupling, enabling higher power transfer capabilities beyond the limitations of existing near-field WPT technologies.
Implementation Method 1
Faraday's law of magnetic induction provides that if a time-varying current is applied to one coil (e.g., a transmitter coil) a voltage will be induced in a nearby second coil (e.g., a receiver coil)
Implementation Method 2
The flux pattern of the magnetic field between the transmitter coil and the receiver coil is commonly not uniform, or 'fuzzy,' and thus the transfer of power from the transmitter coil to the receiver coil is not very efficient
Data Source
AI summary
In one embodiment, a wireless power transfer coil structure comprises a wheel core comprising an annulus portion and at least two spoke portions arranged substantially symmetrically with respect to a geometric center of the annulus portion, the wheel core formed from a magnetic material, and a coil located on an outer surface of the annulus portion of the wheel core. In one embodiment, the wireless power transfer coil structure further comprises at least one solenoidal coil wound around the at least two spoke portions of the wheel core. In one embodiment, the at least one solenoidal coil is wound around one of the at least two spoke portions of the wheel core in a first direction and wound around another of the at least two spoke portions of the wheel core in the first direction. In one embodiment, the at least one solenoidal coil is wound around one of the at least two spoke portions of the wheel core in a first direction and wound around another of the at least two spoke portions of the wheel core in a second direction different from the first direction.