Steering Coil Magnetic Field Phase Control for Wireless Charging

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Solution Overview

Problem

Inductive charging systems for devices like power toothbrushes, which use a cup receptacle charger, face inefficiencies due to the lack of close alignment between the primary and secondary coils, resulting in extended charging times, often by 50% or more, as the secondary coil is angled relative to the primary coil in such arrangements.

Innovation Solution

A charging system with a receptacle charger containing a primary coil and a plurality of steering coils around it, controlled to adjust the magnetic field phase, ensuring optimal alignment and power transfer between the primary and secondary coils, even when the device is not perfectly aligned, by determining the phase pattern that maximizes energy transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a cup receptacle charger is used to allow easy insertion of the target device, then ease of operation is improved, but charging efficiency deteriorates due to misalignment between primary and secondary coils

Engineering Contradiction:
Improveease of insertionVSAvoidcharging efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent applies dynamics by making the magnetic field configuration adjustable rather than fixed. The control system dynamically modifies the phase and amplitude of currents in steering coils to adapt to different target device positions, enabling the system to maintain high charging efficiency regardless of alignment variations caused by easy insertion into the cup receptacle

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes magnetic field parameters (phase and amplitude) by controlling the steering coils. The control system varies these parameters to optimize the magnetic field distribution, allowing the system to compensate for misalignment between coils and maintain efficient power transfer even when the target device is loosely positioned in the cup receptacle

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the secondary coil is positioned at an angle relative to the primary coil in a cup receptacle, then adaptability is improved, but charging time increases by 50% or more

Engineering Contradiction:
Improvecoil positioning flexibilityVSAvoidcharging time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The system dynamically adjusts the magnetic field configuration through the control system, which modifies steering coil parameters in real-time based on detected target device positions. This dynamic adaptation allows the system to maintain efficient charging across various coil angular positions, preventing the 50%+ time extension that would otherwise occur with fixed-field systems

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system employs feedback by detecting the position and orientation of the target device's secondary coil relative to the primary coil, then using this information to adjust the steering coil parameters. This closed-loop control enables the system to compensate for angular misalignment and maintain optimal charging efficiency regardless of how the target device is positioned in the cup receptacle

Inventive Principle:
Principle #23Feedback

3Productivity

If steering coils are added to optimize magnetic field alignment, then power transfer efficiency is improved, but device complexity increases

Engineering Contradiction:
Improvepower transfer efficiencyVSAvoidcharging system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the magnetic field generation function by separating the primary coil from multiple steering coils, each with independent control. This segmentation allows the system to optimize power transfer efficiency by independently adjusting each steering coil's contribution to the overall magnetic field, while the modular structure makes the added complexity manageable and controllable

Inventive Principle:
Principle #1Segmentation

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 solution significantly reduces charging time by optimizing power transfer, achieving efficiency comparable to conventional charging systems, even when the secondary coil is not aligned with the primary coil, thereby enhancing the usability of cup receptacle chargers.

Implementation Method 1

wherein in operation energy is inductively transferred between the primary coil and secondary coil to charge a battery in the target device

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a control system for controlling the magnetic field phase of the steering coils relative to the magnetic field of the primary coil so as to focus the magnetic field lines of the primary coil for aligning the magnetic field of the primary coil with the position of the secondary coil

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP2795761B1Charging coil system for a drop-in target device such as a toothbrush
Publication Date: 2018.02.21 KONINKLIJKE PHILIPS NV
  • EP2795761B1 patent drawingFigure 1~3
  • EP2795761B1 patent drawingFigure 4~5
  • EP2795761B1 patent drawingFigure 6

AI summary

A system and method for charging at least one target device (29) having a secondary coil (27) positionable in a charging receptacle (25) having a primary coil (23) connected to a source of electrical power, wherein the secondary coil of the target device is out of precise alignment with the primary coil when the target device is positioned in the receptacle. A plurality of steering coils (22-22) are arranged around the primary coil. A control circuit (24) changes the magnetic field phase pattern of the steering coils relative to the phase of magnetic field of the primary coil in a selected sequence until the maximum power transfer between the primary coil and the secondary coil is determined. Charging of the target device is continued with the maximum power transfer steering coil phase pattern.