Wireless Power Reception Coil With Switchable Winding Regions
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Solution Overview
Problem
Existing wireless power feeding systems face challenges in efficiently matching impedance between the power transmission and reception coils due to changes in positional relationships and load fluctuations, leading to reduced power transmission efficiency and potential system failures.
Innovation Solution
The system employs a power reception coil capable of selecting multiple coil regions with different numbers of windings, and a controller that adjusts the inductance of the power reception coil by switching terminals to mitigate impedance differences. Additionally, the system includes a driving unit with a driver coil that can change its coupling strength with the power transmission coil to further adjust impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a variable inductor or variable capacitor is used to adjust impedance while maintaining resonant state, then impedance matching can be achieved, but the responsiveness is insufficient and it is difficult to meet both resonant state conditions and impedance matching conditions concurrently
Solution Approach 1:
The power reception coil is divided into multiple discrete coil regions with different numbers of windings. By switching between these segmented regions, the inductance can be changed in discrete steps, providing faster and more responsive impedance adjustment compared to continuous adjustment methods while maintaining resonant state.
Solution Approach 2:
The system dynamically switches between different coil regions based on real-time impedance requirements. This dynamic switching capability allows the system to rapidly adapt to changing impedance conditions, meeting both resonant state maintenance and impedance matching requirements concurrently.
2Reliability
If high-performance elements are added to achieve impedance matching function, then impedance matching performance improves, but the device becomes costly and complex
Solution Approach 1:
The power reception coil serves multiple functions: it is both the resonant element and the impedance adjustment mechanism. By incorporating multiple coil regions with different windings into a single coil structure, the system achieves impedance matching capability without adding separate high-performance elements, thus avoiding increased cost and complexity.
Solution Approach 2:
The impedance adjustment function is merged with the power reception coil itself rather than being implemented through separate components. The multiple coil regions are integrated into a single unified structure, simplifying the overall device architecture while maintaining effective impedance matching performance.
3Reliability
If multiple driver coils are switched to change magnetic field coupling strength for impedance matching, then impedance can be adjusted, but power feeding speed slows down during switching
Solution Approach 1:
The power reception coil is segmented into multiple coil regions that can be independently selected. This segmentation allows for rapid switching between regions without the mechanical or electrical complexity of switching multiple driver coils, thereby maintaining high power feeding speed while achieving impedance matching.
4Reliability
If the power reception device is equipped with complex impedance matching mechanism, then impedance matching performance improves, but weight, size, and heat generation increase making it impractical for mobile devices
Solution Approach 1:
The power reception coil is designed to perform both power reception and impedance matching functions simultaneously. The multiple coil regions are integrated into the existing coil structure without requiring additional components, thereby avoiding increases in weight, size, and heat generation that would make the device unsuitable for mobile applications.
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 effectively reduces the generation of reflected waves at the input end, maintaining high power transmission efficiency and preventing system failures caused by impedance mismatches.
Implementation Method 1
transmits and receives power between the power transmission coil and the power reception coil using a magnetic field resonance method
Implementation Method 2
An electromagnetic coupling (electromagnetic inducing) method and a magnetic field resonance method are known as such power feeding methods using magnetism
Implementation Method 3
the controller changes an inductance of the power reception coil by switching the plurality of terminals to mitigate a difference between a load side impedance and an input side impedance
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
[Problem] To provide a wireless power feeding system, a wireless power feeding method, and a wireless power receiving system that can easily execute impedance matching even in the case of fluctuations of impedances of a load side circuit. [Solution] In a wireless power feeding system (1) that transmits and receives power between a power transmission coil (32) and a power reception coil (41) using the magnetic field resonance method, the power reception coil (41) is configured to be capable of selecting a plurality of coil regions (41A, 41B, 41C) that have different numbers of coil windings in accordance with the connecting positions of a plurality of terminals provided at the power reception coil (41), and a controller (92) changes an inductance of the power reception coil (41) by switching the plurality of terminals to mitigate the difference between a load side impedance, which is an impedance from the input end (IE) of the power transmission device (3) to a circuit on the load (8) side, and an input side impedance, which is an impedance from the input end (IE) of the power transmission device (3) to a circuit on the AC power source (5) side.