Wireless Charging Foreign Object Detection With Adaptive Ping Thresholds
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Solution Overview
Problem
Current wireless power transfer systems struggle to accurately detect foreign objects and friendly metal interactions due to variance in energy absorption, which limits operational range and can cause overheating, especially with large lateral offsets or misalignment.
Innovation Solution
The system employs a method involving analog and digital pings to measure decay rates and oscillation times, differentiating between friendly foreign objects and real foreign objects by adjusting thresholds and resonance frequencies, allowing for more precise detection and efficient power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmitter uses a high detection threshold to avoid false detection of friendly foreign objects, then false detection is reduced, but real foreign objects may not be detected properly
Solution Approach 1:
The system dynamically adjusts the detection threshold based on the measured coupling coefficient. When coupling is strong (indicating proper alignment), a higher threshold is used to tolerate friendly foreign objects. When coupling is weak (indicating misalignment), a lower threshold is used to detect real foreign objects that would cause dangerous overheating.
Solution Approach 2:
The detection threshold parameter is changed based on the coupling coefficient measurement. The system calculates an adjusted threshold that scales with the coupling strength, allowing the same hardware to adapt its detection sensitivity to the operational conditions.
2Reliability
If the system activates foreign object detection for large offsets, then safety is improved, but the operational range is limited
Solution Approach 1:
The detection threshold is dynamically adjusted based on the measured coupling coefficient, which varies with offset distance. This allows the system to maintain safe detection at large offsets while permitting acceptable operation at smaller offsets where friendly foreign object effects are minimal.
3Measurement precision
If the system uses a low detection threshold to detect real foreign objects, then detection sensitivity is improved, but friendly foreign objects may be falsely detected
Solution Approach 1:
The detection threshold dynamically adapts to the coupling coefficient. At strong coupling (small offsets), the threshold is raised to tolerate friendly foreign objects. At weak coupling (large offsets), the threshold is lowered to detect real foreign objects with high sensitivity.
Solution Approach 2:
The system changes the detection threshold parameter based on the measured coupling conditions, transforming a static detection system into an adaptive one that optimizes sensitivity based on operational context.
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 foreign object detection accuracy, preventing overheating and improving operational range by distinguishing between friendly and real foreign objects, enabling safer and more efficient wireless charging.
Implementation Method 1
transfer power from a transmitting coil in a transmitter to a receiving coil in a receiver. The power is transferred via an alternating magnetic field induced by the transmitting coil.
Implementation Method 2
Foreign objects in the presence of a magnetic field may overheat and may cause fire or burns.
Implementation Method 3
measuring a decay rate and an oscillation time of the measured decay pattern
Data Source
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AI summary
A power transmitter (101) may send a digital ping to a receiver. The power transmitter (101) may transfer power to the receiver (102). The power transmitter may receive a report from the receiver which may comprise a received power value. The power transmitter may determine a transmitted power parameter value, which may be based on a threshold value subtracted from a transmitter power and based on transmitter losses subtracted from the transmitter power. The power transmitter may determine that the received power value is less than the determined transmitted power parameter value and may send an analog ping to the receiver in response to a determination that the received power value is less than the determined transmitted power parameter value. The power transmitter may measure a decay pattern of the analog ping. The power transmitter may determine that the receiver comprises a friendly foreign object. The power transmitter may update the threshold value.