Variable Inductance Wireless Power Resonator

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Solution Overview

Problem

Resonant magnetic coupling wireless power transmission systems face challenges in maintaining high efficiency across multiple operating conditions without increasing the overall length of wiring, particularly when dealing with impedance variations in power sources and loads.

Innovation Solution

A wireless power transmission system incorporating a series resonant circuit with a variable inductor and capacitors, where the inductance is adjusted by selectively turning on switches connected to extended wires, maintaining a constant resonant frequency and optimizing impedance matching between the power transmitter and receiver.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the overall length of wiring is increased to cope with multiple different operating conditions, then the system can adapt to impedance variations, but the transmission efficiency decreases

Engineering Contradiction:
Improveimpedance adaptation capabilityVSAvoidtransmission efficiency
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the resonator's inductance variable rather than fixed. The inductor includes multiple connection points with switches that allow selective connection to different tap points, enabling the inductance to be dynamically adjusted based on operating conditions. This dynamic adjustment allows the system to adapt to impedance variations without requiring increased wiring length, thereby maintaining transmission efficiency while achieving versatility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the inductance parameter of the resonator by providing an inductor with multiple tap points at different positions along its winding. By selectively connecting to different tap points via switches, the effective inductance value is changed to match different operating conditions. This parameter change approach enables impedance adaptation without physically extending the wiring, thus avoiding the efficiency loss that would result from increased wiring length.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If impedance matching is maintained between power transmitter and resonator, and between power receiver and resonator, then high-efficiency energy transfer is achieved, but the system cannot cope with impedance variation

Engineering Contradiction:
Improveenergy transfer efficiencyVSAvoidimpedance variation tolerance
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamics by providing variable inductance capability in the resonator through multiple connection points. This allows the system to dynamically adjust the inductance value to maintain impedance matching under varying operating conditions. The control unit selectively activates different switches to change the inductance, ensuring continuous optimal impedance matching despite impedance variations in the power source or load, thereby maintaining high energy transfer efficiency across different scenarios.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent achieves universality by designing the resonator with multi-tap inductor and switch matrix that can accommodate multiple operating conditions through a single configuration. The same resonator structure can adapt to different impedance requirements by changing its inductance value, making it universally applicable to various power sources and loads without requiring separate dedicated configurations for each scenario.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Loss of energy

If a resonant magnetic coupling method is used to achieve longer range and higher efficiency power transmission, then power transmission performance is improved, but the system requires strict impedance matching which reduces adaptability

Engineering Contradiction:
Improvepower transmission efficiencyVSAvoidapplicability to different power sources and loads
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics to the resonant magnetic coupling system by enabling variable inductance in the resonator. This allows the system to maintain optimal impedance matching across different operating conditions while preserving the benefits of resonant magnetic coupling. The dynamic adjustment capability ensures that the system can adapt to different power sources and loads without sacrificing transmission efficiency, thereby resolving the contradiction between achieving high efficiency and maintaining adaptability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the inductance parameter of the resonator to enable adaptation to different power sources and loads. By providing multiple tap points on the inductor and selectively connecting them, the system can adjust its inductance value to match different impedance requirements while maintaining resonant magnetic coupling operation, thus achieving both high transmission efficiency and broad applicability.

Inventive Principle:
Principle #35Parameter changes

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 system maintains high transmission efficiency across varying impedance conditions without increasing the length of wiring, ensuring efficient power transfer to a wide range of devices, including electronic devices, electric vehicles, and solar or fuel cell systems.

Implementation Method 1

a resonant magnetic coupling method has been proposed in Patent Document No. 1. According to such a method, resonant mode coupling between resonant antennas is used to realize longer range and higher efficiency power transmission than the conventional electromagnetic induction method

Methodology Applied
Scientific EffectResonant magnetic coupling: Resonance

Implementation Method 2

The resonant magnetic coupling power transmission system may be regarded as an electromagnetic induction system that does not have a coupling coefficient k of one

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2555376B1Wireless power transmission system
Publication Date: 2019.08.07 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP2555376B1 patent drawingFigure 1~2
  • EP2555376B1 patent drawingFigure 3
  • EP2555376B1 patent drawingFigure 4

AI summary

The wireless power transmission system of this invention transmits power over a resonant magnetic field. The system includes a power-transmitting resonator 105 and a power-receiving resonator 107, at least one of which is a series resonant circuit with an inductor including spiral wiring 201 and extended wires 213, 207a, 207b and 207c. The extended wire 213 connects a point 203 of the spiral wiring 201 to a power supplying structure, while the extended wires 207a, 207b and 207c connect other points of the spiral wiring 201 to the power supplying structure. Capacitors 209a, 209b and 209c and switches 211a, 211b and 211c are connected to the extended wires 207a, 207b and 207c, respectively. The series resonant circuit has its inductance varied according to which current path has been chosen by selectively turning ON one of the switches. A wiring portion 201a of the spiral wiring 201 has a low-resistance portion 2010, of which the wiring resistance per unit length at a resonant frequency is set to be lower than in at least a part of the rest of the spiral wiring.