Wireless Power Transfer Foreign Object Detection
Solution Overview
Problem
Existing wireless power supply systems face inefficiencies due to foreign matter interference, such as metal objects, which can cause eddy currents and heat generation, leading to decreased power transmission efficiency and incorrect detection of foreign matter.
Innovation Solution
A dual detection method is employed in the power reception apparatus, using a first detection method before power supply initiation and a second method during power supply, involving Q-value measurement, effective resistance, and power efficiency analysis to accurately identify and mitigate foreign matter interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single detection method is used to detect foreign matter, then the detection process is simple, but the detection accuracy is insufficient and cannot differentiate between displacement and foreign matter
Solution Approach 1:
The detection process is divided into two distinct phases: a first detection method executed before power supply to detect initial foreign matter, and a second detection method executed during power supply to detect foreign matter that affects power transmission. This segmentation allows each detection method to be optimized for its specific purpose, improving overall detection accuracy without requiring a single complex system to handle all scenarios
Solution Approach 2:
The first detection method is performed as a preliminary action before power supply begins. This preliminary detection identifies foreign matter in advance, allowing the system to prevent incorrect power transmission decisions. By performing detection before the main operation, the system avoids the complexity of trying to detect foreign matter during active power transmission while maintaining high accuracy
2Productivity
If power supply continues without accurate foreign matter detection, then power transmission efficiency may decrease due to undetected foreign matter, but stopping power supply for detection causes interruption
Solution Approach 1:
The first foreign matter detection is performed as a preliminary action before power supply begins. This ensures that foreign matter is detected in advance, preventing energy loss from incorrect power transmission, while allowing power supply to proceed continuously without interruption once started. The preliminary detection eliminates the need to interrupt ongoing power transmission for detection
Solution Approach 2:
The second detection method operates periodically during power supply transmission. Rather than continuously interrupting power supply, the system performs detection at periodic intervals, allowing power transmission to continue while still monitoring for foreign matter that may affect efficiency. This periodic approach balances productivity maintenance with energy efficiency monitoring
3Loss of energy
If foreign matter is not detected, then power supply efficiency decreases due to eddy currents and heat generation, but detection methods may incorrectly identify displacement as foreign matter
Solution Approach 1:
The detection system is segmented into two methods with different functions: the first method detects foreign matter before power supply to establish a baseline, while the second method detects foreign matter during power supply by comparing against that baseline. This segmentation allows the system to distinguish between actual foreign matter (which would cause efficiency loss) and normal displacement variations, improving both energy efficiency and detection reliability
Solution Approach 2:
The system uses feedback from the first detection method to inform the second detection method. By comparing detection results during power supply against the preliminary detection data, the system can reliably identify actual foreign matter while filtering out false positives from displacement. This feedback mechanism ensures both energy efficiency is maintained and detection reliability is high
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 matter detection and maintains high power supply efficiency by differentiating between displacement and foreign matter-induced efficiency drops, ensuring reliable and efficient wireless power transmission.
Implementation Method 1
Electromagnetic induction methods are already being widely used. In the methods, the degree of coupling between a power transmission apparatus which transmits power and a power reception apparatus which receives power is very high, and power can be supplied highly efficiently.
Implementation Method 2
Magnetic-field resonance methods are methods in which a resonance phenomenon is actively used, and are characterized in that the number of lines of magnetic induction shared by a power transmission apparatus and a power reception apparatus may be small.
Implementation Method 3
If foreign matter capable of receiving energy from a magnetic field, such as metal, is between the power transmission coil and the power reception coil which are magnetically coupled to each other, an eddy current flows through the foreign matter and thereby heat is generated.
Implementation Method 4
an eddy current flows through the foreign matter and thereby heat is generated
Data Source
AI summary
Methods and apparatus for detecting the presence of undesirable foreign matter in a region between a wireless power transmission apparatus and a power reception apparatus are described. First and second detection methods, based on different detection schemes, may be used to detect and distinguish the presence of foreign matter from misalignment during power transfer operation. A first detection method may be used before power is transferred to a load in a power reception apparatus, and a second detection method may be used while power is supplied to the load.