Foreign Matter Detection in Wireless Power Receiving Devices
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Solution Overview
Problem
Existing non-contact power supply systems fail to correctly detect foreign matter, often misidentifying voltage amplitude decreases due to factors other than foreign material presence, leading to incorrect judgments and potential damage.
Innovation Solution
A power receiving device equipped with a measurement coil that measures the electromagnetic field near the power receiving coil, allowing for accurate detection of foreign matter by analyzing induced voltage and current parameters, and a detection circuit that controls charging current based on these measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a circuit judges foreign matter presence based on voltage amplitude threshold, then foreign matter detection is simplified, but false detection occurs when voltage decreases due to other causes
Solution Approach 1:
The patent divides the detection function into two independent circuits: one for detecting voltage amplitude and another for detecting current amplitude. By segmenting the detection task, the system can analyze both parameters separately and make a more accurate judgment about foreign matter presence, reducing false detections while maintaining reasonable circuit complexity.
Solution Approach 2:
The patent changes the detection parameter from single-parameter voltage amplitude detection to dual-parameter detection (voltage amplitude and current amplitude). This parameter expansion allows the system to distinguish between voltage decreases caused by foreign matter versus those caused by other factors like power supply issues, thereby improving detection accuracy.
2Reliability
If power supply amount or transmission efficiency decreases, then voltage amplitude decreases, but existing systems cannot distinguish this from foreign matter presence
Solution Approach 1:
The patent implements a feedback mechanism where the detection circuit continuously monitors both voltage and current amplitudes and uses this information to determine foreign matter presence. By feedback-based dual-parameter analysis, the system can identify whether voltage decrease is due to foreign matter (which would show specific voltage-current relationship changes) or other causes, improving both reliability and detection precision.
3Ease of operation
If power supply device fails or deteriorates, then power supply efficiency decreases and voltage amplitude drops, leading to erroneous foreign matter detection
Solution Approach 1:
The patent segments the detection judgment into two independent amplitude measurements (voltage and current) that can be evaluated separately. This segmentation allows the system to maintain simple operation while improving accuracy, as the judgment logic can systematically compare both parameters without requiring complex analysis.
Solution Approach 2:
The patent introduces current amplitude as an additional detection parameter to complement voltage amplitude measurement. This parameter change enables the system to distinguish between genuine foreign matter presence and power supply issues, maintaining ease of operation through straightforward dual-threshold comparison while significantly improving detection accuracy.
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
Enables precise detection of foreign matter, preventing damage by distinguishing between foreign material presence and other causes of voltage decrease, ensuring reliable power transmission.
Implementation Method 1
a power receiving coil which receives power supplied by electromagnetic waves
Implementation Method 2
a measurement coil which is disposed near the power receiving coil and measures an electromagnetic field
Implementation Method 3
when foreign matter of a conductor is mixed into a magnetic field, an eddy current arises in the foreign matter
Implementation Method 4
the foreign matter sometimes generates heat under the influence of Joule heat generated by the eddy current
Data Source
AI summary
Provided is a power receiving device including a power receiving coil which receives power supplied by electromagnetic waves, and a measurement coil which is disposed near the power receiving coil and measures an electromagnetic field.