Wireless Power Coil Foreign Object Detection Interference
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Solution Overview
Problem
Wireless charging systems face interference from nearby wireless power transmitting devices during foreign object detection, which can reduce charging efficiency and accuracy in detecting foreign objects like coins or paperclips.
Innovation Solution
A wireless power system employs a separate sensing coil to measure and subtract noise signals from the wireless power transmitting coil, and adjusts the timing of foreign object detection periods based on signal quality metrics to minimize interference from adjacent transmitters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate sensing coil is used to detect foreign objects, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the detection function into two separate coils: a power transmitting coil for wireless power transfer and a separate sensing coil for foreign object detection. This segmentation allows each coil to be optimized for its specific function, improving detection precision while maintaining manageable device complexity through functional separation.
2Productivity
If foreign object detection is performed during power transmission, then productivity is improved, but measurement precision deteriorates due to interference
Solution Approach 1:
The patent implements periodic foreign object detection during the wireless power transmission process, where the system alternates between power transmission phases and detection phases. This periodic action allows the system to maintain high charging efficiency while periodically verifying foreign object absence, balancing productivity with measurement precision.
Solution Approach 2:
The separate sensing coil acts as an intermediary element that detects foreign objects without interfering with the primary power transmission function. By using this dedicated sensing coil, the system can perform detection during power transmission without the measurement interference that would occur if the power coil itself were used for detection.
3Measurement precision
If signal subtraction is used to remove interference, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces a separate sensing coil as an intermediary that captures only the interference signals from adjacent transmitters. These sensed interference signals are then subtracted from the total signals received by the power transmitting coil, effectively removing the interference component and improving measurement precision through relatively simple signal processing.
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 the accuracy of foreign object detection and reduces interference, ensuring reliable power transfer by effectively distinguishing between foreign objects and noise signals.
Implementation Method 1
the wireless power transmitting device gathers signals with a sensing coil that is separate from the wireless power transmitting coil
Implementation Method 2
The wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device
Data Source
AI summary
A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device during wireless power transmission periods. During alternating foreign object detection periods, the wireless power transmitting device gathers signals from the wireless power transmitting coil to detect foreign objects. Another wireless power transmitting device may transmit signals that can cause interference. To help reduce interference, the wireless power transmitting device gathers signals with a sensing coil that is separate from the wireless power transmitting coil and subtracts these signals from signals gathered with the wireless power transmitting coil. A signal quality metric may be used in adjusting the timing of the foreign object detection periods to help avoid interference from the other wireless power transmitting device.