Foreign Object Detection in Wireless Power Transmission
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Solution Overview
Problem
Conventional wireless power transmission systems face challenges in detecting foreign objects, which can disrupt power transmission and potentially cause damage or safety issues due to the presence of metallic objects between the transmitting and receiving apparatuses.
Innovation Solution
A method and apparatus for detecting foreign objects in a wireless power transmission system by monitoring current induced in a primary coil, using communication protocols (one-way or two-way) to identify foreign objects before or during charging, and implementing power limiting mechanisms to prevent damage, including the use of temperature sensors to manage heat-related risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless power transmission is used to eliminate cables and contacts, then ease of operation and workspace organization are improved, but the risk of foreign object insertion and associated safety hazards increases
Solution Approach 1:
The system performs foreign object detection during the initial recognition stage, before power transmission begins. By detecting foreign objects in advance and preventing power transmission when foreign objects are present, the system resolves the contradiction by maintaining the wireless convenience while preemptively eliminating the safety hazard through early detection and prevention mechanisms
Solution Approach 2:
The system continuously monitors parameters such as current induced in the primary coil and temperature during power transmission. When foreign objects are detected through these feedback mechanisms, the system automatically limits or stops power transmission, thereby maintaining ease of wireless operation while dynamically responding to and mitigating foreign object risks
2Reliability
If foreign object detection is performed continuously during power transmission, then detection reliability is improved, but energy consumption and system complexity increase
Solution Approach 1:
The system performs foreign object detection at specific intervals and stages: during the initial recognition stage before power transmission, and at periodic intervals during power transmission by monitoring parameters such as primary coil current. This periodic detection approach maintains reliable foreign object detection while avoiding continuous monitoring, thereby resolving the contradiction between detection reliability and energy consumption
Solution Approach 2:
The system utilizes existing operational parameters (such as current induced in the primary coil during normal power transmission) for foreign object detection purposes. By repurposing parameters already being measured for power control, the system achieves reliable detection without requiring additional dedicated detection resources, thus maintaining detection reliability while minimizing energy consumption
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
Enhances the safety and efficiency of wireless power transmission by autonomously detecting foreign objects, preventing damage and ensuring compatibility with various products, while reducing the risk of overheating and improving power transmission reliability.
Implementation Method 1
a wireless power transmitting apparatus which transmits power wirelessly to a wireless power receiving apparatus by generating an induced magnetic field or magnetic resonance through a primary coil
Implementation Method 2
a wireless power receiving apparatus which receives electric energy provided wirelessly from the wireless power transmitting apparatus
Implementation Method 3
a method for detecting a foreign object by a wireless power transmitting system... based on a current induced to a primary coil
Data Source
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AI summary
An apparatus and a method for detecting foreign objects in a wireless power transmitting system are disclosed. The wireless power transmitting apparatus or the wireless power receiving apparatus determines whether a foreign object is detected prior to initial charging (S205). When a foreign object is detected, the wireless power transmitting apparatus or the wireless power receiving apparatus performs a power limit operation in response to the detection of the foreign object (S225). If a foreign object is not detected prior to the initial charging, the wireless power transmitting apparatus or the wireless power receiving apparatus performs an operation of foreign object detection during charging, after charging starts (S210). If a foreign object is not detected during charging, a problem may arise in power transmission due to a fine foreign object which has not been detected, and thus, the wireless power transmitting apparatus of the wireless power receiving apparatus limits power based on a temperature sensor (S220).