Wireless Power Foreign Object Detection via Temperature Monitoring
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Solution Overview
Problem
Wireless power transfer systems face inefficiencies due to foreign objects intercepting energy, causing eddy currents and ohmic losses, making it difficult to determine if energy is being transferred to the intended receiving device or a foreign object, and variations in coil placement further complicate system efficiency.
Innovation Solution
The system employs methods such as detuning, monitoring load impedance, using satellite coils to determine coil alignment, and measuring temperature and capacitance changes to detect foreign objects, allowing for adjustments to prevent overheating and ensure efficient power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If wireless power transfer is performed between transmitter and receiver coils, then power transfer capability is improved, but foreign objects may intercept energy causing eddy currents and ohmic losses that reduce system efficiency
Solution Approach 1:
The system performs foreign object detection before initiating full power transfer by measuring temperature rise or impedance changes during a preliminary detection phase. This preliminary action identifies foreign objects that would cause energy losses, allowing the system to prevent or adjust power transfer accordingly.
Solution Approach 2:
The system continuously monitors parameters such as temperature, impedance, or coupling coefficient during power transfer and uses this feedback to detect foreign objects. When foreign objects are detected through these monitoring mechanisms, the system adjusts or terminates power transfer to prevent energy losses from eddy currents and ohmic heating.
2Difficulty of detecting and measuring
If foreign object detection is implemented through temperature monitoring, then foreign object detection capability is improved, but detection time and system complexity increase
Solution Approach 1:
The system uses multiple detection methods simultaneously, with temperature monitoring as one component. By combining temperature monitoring with impedance measurement or coupling coefficient detection, the system achieves reliable foreign object detection without requiring extended temperature measurement periods, thus reducing overall detection time.
Solution Approach 2:
The system employs a multi-functional detection approach where the same sensing mechanisms (temperature sensors, impedance measurement circuits) serve both power transfer optimization and foreign object detection functions. This multi-functionality allows comprehensive foreign object detection without significantly increasing system complexity or detection time.
3Loss of energy
If coil placement is optimized for maximum power transfer, then power transfer efficiency is improved, but variations in placement make foreign object detection more difficult
Solution Approach 1:
The system continuously monitors the coupling coefficient or impedance between transmitter and receiver coils to detect changes that indicate foreign object presence. This feedback mechanism works independently of coil placement optimization, allowing the system to maintain high power transfer efficiency while simultaneously detecting foreign objects through parameter monitoring.
Solution Approach 2:
The system monitors changes in electrical parameters such as impedance, coupling coefficient, or resonant frequency that occur when foreign objects are introduced. These parameter changes provide foreign object detection capability that is independent of coil placement, allowing the system to maintain optimized power transfer while detecting foreign objects through parameter variations.
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
Effective detection and prevention of foreign object interference improve the efficiency of wireless power transfer by reducing energy loss and ensuring accurate communication between the transmitter and receiver coils.
Implementation Method 1
Power transfer is intended to occur between a transmitting device and a receiving device
Implementation Method 2
These foreign objects may provide a path which generates eddy currents causing electrically induced thermal dissipation
Implementation Method 3
generates eddy currents causing electrically induced thermal dissipation
Data Source
AI summary
A wireless power transfer foreign object detector having, at least one secondary receiver coil, an adjustable load electrically coupled to the at least one secondary receiver coil, and at least one temperature sensor providing at least one temperature detection signal, wherein the at least one temperature sensor responsive to at least one thermal state of the at least one secondary receiver coil, and wherein foreign object detection is based at least in part upon the at least one temperature detection signal.