Active Shielding Coil Placement for Wireless Charging Field Reduction

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Solution Overview

Problem

Wireless charging systems generate excess magnetic fields that can lead to impactful radiation exposure for humans, as the resonant inductive coupling between power transmit units (PTUs) and power receive units (PRUs) results in leakage magnetic fields exceeding safe exposure limits.

Innovation Solution

The implementation of active shielding coils and optimized coil placement algorithms to minimize magnetic field exposure, where active shielding coils carry current opposite to the primary turns, and the PTUs are positioned within furniture to maintain localized field exposure below regulatory limits, using an exponential decay model for coil placement to reduce radiated leakage magnetic fields.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If wireless charging coils are used for electromagnetic coupling to charge batteries, then wireless charging capability is improved, but magnetic field radiation exposure to humans increases

Engineering Contradiction:

Improvewireless charging capabilityVSAvoidmagnetic field radiation exposure

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

A shielding coil is introduced as an intermediary element between the primary transmitting coil and the surrounding environment. This shielding coil carries current in the opposite direction to generate a counteracting magnetic field that cancels out the harmful radiation, thereby maintaining wireless charging functionality while reducing magnetic field exposure to safe levels

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The shielding coil is configured to produce a magnetic field that opposes and neutralizes the harmful magnetic field from the primary coil before it can radiate into the surrounding environment. This preliminary anti-action prevents the harmful effect from propagating while preserving the useful electromagnetic coupling for charging

Inventive Principle:

Principle #9Preliminary anti-action

2Area of stationary object

If multiple wireless charging coils are deployed in furniture, then wireless charging coverage is improved, but superimposed magnetic field exposure increases

Engineering Contradiction:

Improvewireless charging coverage areaVSAvoidsuperimposed magnetic field exposure

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

Shielding coils are deployed with each primary transmitting coil in the furniture setup. These intermediary shielding coils individually manage the magnetic field from each primary coil, ensuring that when multiple coils operate simultaneously, their combined magnetic field exposure remains within safe limits through cumulative cancellation effects

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Each primary-coil combination in the furniture is equipped with its own dedicated shielding coil, creating localized field management zones. This allows each charging location to independently control its magnetic field exposure while collectively providing broad coverage across the entire furniture surface

Inventive Principle:

Principle #3Local quality

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 significantly reduces magnetic field exposure to safe levels, ensuring compliance with regulatory limits while maintaining effective wireless charging capabilities, with a notable reduction in magnetic field strength and improved user safety in environments with multiple wireless charging coils.

Implementation Method 1

a power transmit unit coil, including a set of main windings, positioned at a first location on a structure, to carry a first current in a first direction, wherein the first current is to cause an electromagnetic field to emanate from the power transmit unit coil

Methodology Applied

Scientific EffectElectromagnetic field generation: Electromagnetic Induction

Implementation Method 2

an active shielding coil, positioned at a second location on the structure, to carry a second current in a direction substantially opposite the first direction wherein the second current is to cause a reduction of the size of the electromagnetic field

Methodology Applied

Scientific EffectElectromagnetic field cancellation: Electromagnetic Induction

Data Source

PatentUS10516304B2Wireless charging coil placement for reduced field exposure

Publication Date: 2019.12.24 INTEL CORP

AI summary

An apparatus is described herein. The apparatus includes a power transmit unit coil and an active shielding coil. The power transmit unit coil includes a set of main windings, positioned at a first location on a structure, to carry a first current in a first direction, wherein the first current is to cause an electromagnetic field to emanate from the power transmit unit coil. The active shielding coil is positioned at a second location on the structure and is to carry a second current in a direction substantially opposite the first direction wherein the second current is to cause a reduction of the size of the electromagnetic field.