Wireless Power Receiver Q Factor Reporting for Foreign Object Detection

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Solution Overview

Problem

Wireless power transfer systems face challenges in accurately detecting foreign objects due to differences in characteristics among wireless power receivers, leading to potential power transfer issues, overload, or even fire and explosion risks.

Innovation Solution

The method involves using a reference Q factor to improve foreign object detection reliability by transmitting digital pings, identification packets, and foreign object detection state packets between the wireless power transmitter and receiver, with the receiver reporting a reference Q factor to the transmitter for accurate foreign object detection based on magnetic coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If wireless power transfer is performed using contactless charging, then convenience and mobility are improved, but foreign objects may lie between the transmitter and receiver causing power transfer issues, overload, or fire damage

Engineering Contradiction:

Improveconvenience of wireless chargingVSAvoidforeign object interference

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The system performs foreign object detection before initiating full power transfer by measuring the Q-factor of the transmitter coil. This preliminary measurement allows the system to identify foreign objects and prevent power transfer that could cause overheating or damage, while still maintaining the convenience of contactless charging.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the Q-factor during the charging process and uses this feedback to detect changes in the electromagnetic environment. When the Q-factor changes indicate the presence of a foreign object, the system adjusts or stops power transfer to prevent harmful effects, thereby maintaining safety without compromising the ease of wireless charging operation.

Inventive Principle:

Principle #23Feedback

2Reliability

If foreign object detection methods are introduced, then safety is improved, but detection accuracy is reduced due to differences in individual wireless power receiver characteristics

Engineering Contradiction:

Improvesafety of power transferVSAvoidforeign object detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system uses the Q-factor as an intermediary parameter to indirectly detect foreign objects. Instead of directly detecting foreign objects, the system measures changes in the transmitter coil's Q-factor, which are affected by both foreign objects and receiver characteristics. By establishing baseline Q-factor values and detecting deviations from these baselines, the system achieves reliable foreign object detection that accounts for individual receiver differences.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system monitors changes in the Q-factor parameter rather than relying on a fixed threshold. By comparing the current Q-factor against baseline values established during system initialization or previous operations, the system can detect foreign objects while adapting to different receiver characteristics. This dynamic parameter-based approach improves both detection accuracy and reliability across different device types.

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

This approach enhances the accuracy and reliability of foreign object detection, ensuring safe and efficient power transfer by compensating for individual receiver characteristics and minimizing the risk of power-related accidents.

Implementation Method 1

receiving wireless power through magnetic coupling from the wireless power transmitter

Methodology Applied

Scientific EffectMagnetic coupling: Electromagnetic Induction

Implementation Method 2

a first Q factor which is a Q factor of a reference wireless power transmitter with respect to the wireless power receiver in a state in which no representative foreign object is present around the reference wireless power transmitter, and a second Q factor which is a Q factor of the reference wireless power transmitter with respect to the wireless power receiver in a state in which the representative foreign object is present around the reference wireless power transmitter

Methodology Applied

Scientific EffectQ factor measurement: Resonance

Data Source

PatentUS11569692B2Apparatus and method for performing foreign object detection in wireless power transfer system

Publication Date: 2023.01.31 LG ELECTRONICS INC

AI summary

Provided are an apparatus and method for performing foreign object detection in a wireless power transfer system. The present specification discloses a method comprising receiving a digital ping from the wireless power transmitter; transmitting an identification and configuration packets to the wireless power transmitter; transmitting a foreign object detection (FOD) state packet which indicates a reference Q factor of the wireless power receiver to the wireless power transmitter; and receiving wireless power through magnetic coupling from the wireless power transmitter based on the foreign object detection result of the wireless power transmitter using the reference Q factor. Irrespective of individual characteristics of a wireless power receiver, accuracy and reliability of detecting a foreign object may be improved.