Wireless Charging Foreign Object Detection via Phase Difference
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Solution Overview
Problem
Conventional foreign object detection methods in magnetically coupled wireless charging systems suffer from low detection precision and high system complexity, posing a risk to safety and reliability.
Innovation Solution
A foreign object detection apparatus utilizing a controller, a first resonant network, a signal coupler, and a phase difference detector to determine the phase difference between an excitation signal and a resonance current signal, allowing for accurate detection of foreign objects by analyzing a phase difference signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional foreign object detection methods are used based on electrical parameter changes, then foreign object detection can be performed, but detection precision is low and system complexity is high
Solution Approach 1:
The patent changes the detection parameter from electrical parameters (current, voltage) to phase difference parameters. By measuring the phase difference between the excitation signal and the resonance current signal, the system achieves higher detection precision while simplifying the detection mechanism, as phase difference measurement directly indicates foreign object presence without complex electrical parameter analysis
Solution Approach 2:
The patent replaces complex electrical parameter detection and processing systems with a simpler phase difference measurement system. Instead of using analog circuits to detect current/voltage changes and process them through controllers, the system directly measures phase difference, substituting a complex electrical detection mechanism with a more straightforward phase comparison approach
2Measurement precision
If conventional foreign object detection methods are used, then foreign object detection can be performed, but detection precision is low
Solution Approach 1:
The patent changes the detection parameter from electrical parameters (current, voltage) to phase difference parameters. By measuring the phase difference between the excitation signal and the resonance current signal, the system achieves higher detection precision while simplifying the detection mechanism, as phase difference measurement directly indicates foreign object presence without complex electrical parameter analysis
3Device complexity
If conventional foreign object detection methods are used, then foreign object detection can be performed, but system complexity is high
Solution Approach 1:
The patent replaces complex electrical parameter detection and processing systems with a simpler phase difference measurement system. Instead of using analog circuits to detect current/voltage changes and process them through controllers, the system directly measures phase difference, substituting a complex electrical detection mechanism with a more straightforward phase comparison approach
Solution Approach 2:
The patent extracts only the essential detection function by focusing solely on phase difference measurement. It removes unnecessary complex electrical parameter detection, analog circuit processing, and controller-based analysis, keeping only the critical phase comparison mechanism that directly indicates foreign object presence
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 method reduces system complexity and costs while improving detection precision by directly measuring phase differences, enhancing the safety and reliability of wireless charging systems.
Implementation Method 1
a first resonant network, a signal coupler, and a phase difference detector. The signal coupler is 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
Implementation Method 2
The power transmission apparatus and the power receiving apparatus transfer energy through electromagnetic induction between a transmit coil and a receive coil
Implementation Method 3
The phase difference detector is configured to extract a low-frequency signal component from the coupled current signal, determine a phase difference signal based on the low-frequency signal component
Implementation Method 4
if a foreign object (especially a metal foreign object) such as a coin or tinfoil exists in the spatial gap, the foreign object causes eddy effect under the action of a high-frequency electromagnetic field. Consequently, temperature of the foreign object sharply increases
Data Source
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AI summary
Embodiments of this application provide a foreign object detection apparatus and a foreign object detection method. The foreign object detection apparatus 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. Herein, a frequency of the preset carrier signal is 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. With the apparatus and the method provided in embodiments of this application, costs of foreign object detection can be reduced, and precision of foreign object detection can be improved.