Wireless Power Coil Foreign Object Detection via Inductance and Quality Factor
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Solution Overview
Problem
Current wireless power transmission systems face challenges in accurately detecting foreign objects on charging surfaces, particularly due to the complexity and cost of separate detection coils, and the inaccuracies caused by one-dimensional foreign object detection methods that do not comprehensively consider inductance and quality factor variations.
Innovation Solution
A wireless power transmission apparatus utilizing multiple coils that partially overlap each other, equipped with sensors to measure inductance and quality factor changes, and a controller to calculate feature values for accurate foreign object detection without a separate detection module, by displaying these values on a coordinate plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate detection coil is added to detect foreign objects, then foreign object detection capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The power transmission coil is designed to serve dual purposes: transmitting power wirelessly and detecting foreign objects. By monitoring changes in the coil's electrical characteristics (inductance, quality factor, resonant frequency) during power transmission, the system can identify the presence of foreign objects without requiring separate detection coils, thereby reducing device complexity while maintaining detection capability
Solution Approach 2:
The detection function is merged with the power transmission function by using the same coil and control circuitry. The controller analyzes variations in electrical parameters of the power transmission coil to detect foreign objects, combining what were previously separate functions into a unified system that reduces component count and manufacturing cost
2Ease of operation
If only peak frequency is used for foreign object detection, then detection process is simplified, but detection accuracy deteriorates
Solution Approach 1:
The system transitions from one-dimensional detection (using only peak frequency) to two-dimensional detection by incorporating multiple electrical characteristics simultaneously. The controller monitors both resonant frequency shifts and quality factor changes, creating a more comprehensive detection space that improves accuracy while maintaining relatively simple implementation through multi-parameter analysis
3Measurement precision
If multiple coils are used for comprehensive detection, then detection coverage and accuracy are improved, but device complexity increases
Solution Approach 1:
The charging surface is divided into multiple detection zones, each corresponding to a specific coil's effective detection area. By segmenting the detection space and using multiple coils with overlapping coverage, the system achieves comprehensive detection across the entire charging surface while maintaining manageable complexity through modular coil arrangement and zone-based analysis
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 enables more accurate and comprehensive two-dimensional foreign object detection across a wider range, reducing manufacturing costs and simplifying the circuit structure, while preventing potential overheating or explosion risks.
Implementation Method 1
A wireless power transmission system may include a wireless power transmission apparatus for supplying power through a single coil or multiple coils
Implementation Method 2
a first sensor configured to sense a change in inductance of each of the coils
Implementation Method 3
a second sensor configured to sense a change in a quality factor of each of the coils
Data Source
AI summary
A wireless power transmission apparatus can include a resonant circuit including a plurality of coils and a plurality of capacitor elements respectively connected to the plurality of coils; a first sensor configured to sense a change in inductance of each of the plurality of coils; a second sensor configured to sense a change in a quality factor of each of the plurality of coils; and a controller configured to calculate feature values based on an inductance variation and a quality factor variation for detecting a foreign object, and determine the foreign object is present on a charging surface of the wireless power transmission apparatus based on whether a feature value combination selected from among the feature values falls within a reference region on a coordinate plane formed by an intersection of a first axis and a second axis, in which the first axis is based on inductance variation and the second axis is based on quality factor variation.