Wireless Charger Foreign Object Detection Using Adaptive Peak Frequency

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Solution Overview

Problem

Existing wireless charging systems face challenges in accurately detecting foreign objects, which can lead to reduced efficiency and potential damage due to overheating, as they are not effectively differentiated from intended charging devices.

Innovation Solution

A method and apparatus for detecting foreign objects in wireless charging systems by measuring the quality factor and inductance values of a resonant circuit before a ping phase and comparing them to dynamically determined threshold values based on reference values received from the wireless power receiver, using a weight that increases according to the reference quality factor value to enhance detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If wireless power transmission is performed using electromagnetic induction or resonance, then power can be transferred wirelessly to devices, but foreign objects in the charging area may be heated due to induced electromagnetic signals

Engineering Contradiction:

Improvewireless power transfer efficiencyVSAvoidforeign object heating

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The system performs foreign object detection before initiating full wireless power transmission by measuring quality factor and inductance values during a preliminary ping phase. This preliminary detection prevents foreign object heating by identifying contaminants before high-power transmission begins.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors quality factor and inductance values during charging operations and compares them against dynamically determined thresholds. When foreign objects are detected through these feedback measurements, the system adjusts or terminates power transmission to prevent harmful heating.

Inventive Principle:

Principle #23Feedback

2Ease of operation

If traditional foreign object detection methods are used, then detection can be performed, but accuracy is insufficient leading to false differentiation between foreign objects and intended charging devices

Engineering Contradiction:

Improvedetection operationVSAvoidforeign object detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system uses multiple electrical parameters (quality factor Q and inductance L) instead of single-parameter detection. By measuring changes in both Q and L values and comparing them against dynamically determined thresholds, the system achieves higher detection accuracy and reduces false positives.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The detection thresholds are dynamically determined based on reference quality factor values received from the wireless power receiver. This dynamic adaptation allows the system to adjust to different charging scenarios and device types, improving detection accuracy while maintaining ease of operation.

Inventive Principle:

Principle #15Dynamics

3Productivity

If foreign objects are not accurately detected, then charging can proceed without interruption, but power waste and equipment damage occur

Engineering Contradiction:

Improvecharging continuityVSAvoidpower waste

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The system performs foreign object detection during the ping phase before committing to full power transmission. This preliminary check prevents energy waste by identifying foreign objects early, while the system can still resume charging if no foreign objects are present, maintaining productivity.

Inventive Principle:

Principle #10Preliminary action

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 minimizes unnecessary power waste and equipment damage by accurately identifying foreign objects, ensuring safe and efficient charging operations.

Implementation Method 1

A method and apparatus for detecting foreign objects in wireless charging systems by measuring the quality factor and inductance values of a resonant circuit

Methodology Applied

Scientific EffectElectromagnetic resonance: Resonance

Implementation Method 2

wireless power transmission technology... uses a phenomenon that, when two coils are located adjacent to each other and then current is applied to one coil, a magnetic flux is generated to cause an electromotive force in the other coil

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS12176731B2Method for detecting foreign material, and device and system therefor

Publication Date: 2024.12.24 LG INNOTEK CO LTD

AI summary

A wireless power transmitter including a reception unit configured to receive a foreign object detection (FOD) status packet from a wireless power receiver; and a transmission unit configured to transmit a response indicating whether a foreign object is present in a charging area of the wireless power transmitter to the wireless power receiver, wherein the FOD status packet includes a mode bit field, wherein the mode bit field indicates whether the FOD status packet includes a reference peak frequency of the wireless power receiver, wherein the reference peak frequency is pre-allocated to the wireless power receiver, and wherein the response is determined using a measured peak frequency of a transmitted power signal and an adaptive threshold frequency based on the reference peak frequency included in the FOD status packet.