Resonant Network Foreign Object Detection Using Phase Difference Signals

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Solution Overview

Problem

Conventional foreign object detection in magnetically coupled wireless charging systems suffers from low detection precision and high system complexity, posing safety risks due to the inability to accurately identify metal foreign objects within the charging gap.

Innovation Solution

A foreign object detection apparatus comprising a controller, a first resonant network, a signal coupler, and a phase difference detector, which extracts a phase difference signal to determine the presence of foreign objects by coupling a carrier signal with the resonance current signal, reducing system complexity and improving detection precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional foreign object detection methods using analog circuits to detect current or voltage parameters are employed, then the detection system can be implemented, but the detection precision is low and system complexity increases

Engineering Contradiction:

Improveforeign object detection precisionVSAvoiddetection system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional analog circuit detection methods with a digital signal processing approach. Specifically, it substitutes the mechanical/analog measurement system with a digital system that uses signal coupling and phase difference detection algorithms, thereby improving measurement precision while reducing system complexity through software-based processing rather than complex hardware circuits

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transforms the detection approach by changing from direct current or voltage parameter measurement to phase difference parameter measurement. By coupling a carrier signal with the resonance current signal and detecting the phase difference between them, the system achieves higher detection precision for foreign objects while simplifying the overall detection system architecture

Inventive Principle:

Principle #35Parameter changes

2Reliability

If direct current or voltage parameter detection is used to identify foreign objects, then the detection process can be performed, but the reliability and applicability are low

Engineering Contradiction:

Improveforeign object detection reliabilityVSAvoiddetection method simplicity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces unreliable direct parameter detection with a more reliable phase difference detection system. By using signal coupling and extracting phase information through digital processing, the system achieves higher reliability in foreign object detection while maintaining ease of operation through automated algorithmic processing

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a carrier signal as an intermediary to facilitate reliable detection. The carrier signal couples with the resonance current signal, and the phase difference between them serves as an intermediary parameter that reliably indicates the presence of foreign objects, making the detection process both reliable and operationally simple

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution enables accurate and efficient foreign object detection, enhancing safety and reducing costs by directly processing phase difference signals, thus improving detection precision and reliability compared to conventional methods.

Implementation Method 1

a first resonant network, a signal coupler, and a phase difference detector. The signal coupler may be configured to obtain a resonance current signal corresponding to the first resonant network when the first resonant network operates normally under the action of an excitation signal

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

couple a preset carrier signal to the resonance current signal to obtain a coupled current signal

Methodology Applied

Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Implementation Method 3

extract a low-frequency signal component from the coupled current signal, determine a phase difference signal based on the low-frequency signal component

Methodology Applied

Scientific EffectPhase difference detection: Homodyne Detection

Data Source

PatentUS20230417945A1Foreign object detection apparatus and method, and wireless charging transmit-end device

Publication Date: 2023.12.28 CADENCE DESIGN SYST INC

AI summary

The technology of this application relates to a foreign object detection apparatus that includes a controller, a first resonant network, a signal coupler, and a phase difference detector. The signal coupler may obtain a resonance current signal corresponding to the first resonant network, and couple the resonance current signal to a preset carrier signal to obtain a coupled current signal. A frequency of the preset carrier signal can be the same as a frequency of an excitation signal. The phase difference detector may extract a low-frequency signal component from the coupled current signal, and determine a phase difference signal based on the low-frequency signal component. An amplitude of the phase difference signal correspondingly indicates a phase difference between the excitation signal and the resonance current signal. The controller may determine, based on the amplitude of the phase difference signal, whether a foreign object exists in a detection area corresponding to the first resonant network.