Wireless Power Transmitter Foreign Object Detection via Q Plane
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Solution Overview
Problem
Existing wireless charging technologies face inefficiencies and safety issues due to the presence of metal foreign objects, which can lead to power loss, overheating, and interrupted transmission, particularly in inductive coupling methods, where detecting such objects is challenging, especially with small metal materials or those inside device cases.
Innovation Solution
A method and apparatus that utilize a Q factor detection system, including a Q frequency and Q value, to determine the presence of foreign objects by adjusting a foreign object boundary line in a Q plane, allowing for effective detection and prevention of overheating and fire risks during wireless power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless power transmission is performed using inductive coupling or resonance coupling, then power can be transmitted wirelessly to charging devices, but metal foreign objects between the transmitting and receiving devices cause power loss and overheating risks
Solution Approach 1:
The system performs foreign object detection before initiating full power transmission by measuring Q factor characteristics. This preliminary detection identifies metal foreign objects in advance, preventing power loss and overheating issues before they occur during charging operation.
Solution Approach 2:
The patent replaces physical inspection methods with electromagnetic field-based Q factor measurement for foreign object detection. By monitoring changes in the resonant circuit's Q factor caused by metal objects, the system detects foreign objects without mechanical contact or additional sensors.
2Difficulty of detecting and measuring
If existing foreign object detection methods are used, then detection can be performed, but the detection accuracy decreases when the metal material size is small or when foreign objects are inside device cases
Solution Approach 1:
The patent employs two-dimensional Q factor space (Q frequency vs. Q value) instead of single-parameter detection. This dimensional approach enhances detection sensitivity by analyzing the combined effect of frequency and amplitude changes, making it possible to detect small or enclosed foreign objects that cause subtle variations in both parameters simultaneously.
Solution Approach 2:
The system monitors changes in Q factor parameters (frequency and value) caused by foreign objects. By tracking parameter variations rather than relying on fixed thresholds, the detection system adapts to different foreign object sizes and positions, improving accuracy for small or enclosed objects.
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 enables accurate detection of metal foreign objects, ensuring stable and efficient wireless power transmission by distinguishing between chargeable and non-chargeable states, thereby preventing overheating and fire hazards.
Implementation Method 1
a primary coil for transmitting power by magnetic induction coupling with a secondary coil of a receiving device
Implementation Method 2
a resonance circuit including a primary coil for transmitting power by magnetic induction coupling with a secondary coil of a receiving device, a Q factor detection unit configured to detect a Q frequency and a Q value of the resonance circuit
Data Source
AI summary
The method for transmitting power wirelessly may comprise: transmitting power wirelessly to a receiving device, receiving, from the receiving device, a first Q factor including a Q frequency and a Q value measured by the receiving device while transmitting the power, and obtaining a second foreign object boundary line by adjusting a first foreign object boundary line based on a first Q point corresponding to the first Q factor in a Q plane with a Q frequency and a Q value as two axes. The method may detect, as a second Q factor, a Q frequency and a Q value of a resonance circuit included in a transmitting apparatus, and continue or stop a power transmitting operation based on a comparison of a second Q point corresponding to the second Q factor and the second foreign object boundary line in the Q plane.