LC Q-Factor Detection Circuit for Fast Foreign Object Sensing
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Solution Overview
Problem
Current wireless charging technologies have limited foreign object detection capabilities, leading to potential damage of objects like bank cards or identity cards during charging due to inaccurate detection, which hinders the industry's development.
Innovation Solution
A quality factor measurement circuit and method based on an oscillating circuit are employed to quickly and precisely measure the quality factor of an inductor coil, using a voltage sampling technique to calculate the quality factor without requiring frequency sweep or damped oscillation frequency measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional quality factor measurement methods are used, then measurement accuracy can be maintained, but measurement time increases and productivity decreases
Solution Approach 1:
The patent extracts only the essential information needed for quality factor measurement by sampling the voltage waveform at specific key points (peak points and zero-crossing points) rather than measuring the entire waveform. This extraction approach maintains measurement accuracy while significantly reducing the data processing burden and measurement time, directly resolving the contradiction between measurement precision and productivity.
Solution Approach 2:
The patent performs preliminary identification of key waveform characteristics (peak points and zero-crossing points) during the oscillation process, and uses these pre-identified points for quality factor calculation. This preliminary action allows the system to prepare measurement data in advance, enabling faster computation and improving overall measurement speed without sacrificing accuracy.
2Reliability
If comprehensive foreign object detection is implemented, then safety improves, but device complexity increases
Solution Approach 1:
The patent makes the quality factor measurement circuit serve multiple functions: it measures the quality factor of the transmit coil, detects foreign objects, and monitors charging status. By making this single circuit multi-functional, the system achieves comprehensive detection capability without proportionally increasing device complexity, as the same hardware infrastructure supports multiple detection objectives.
Solution Approach 2:
The system uses its own oscillating circuit and naturally occurring voltage waveforms to perform self-diagnosis and foreign object detection. The transmit coil's own operational characteristics are utilized for monitoring purposes, eliminating the need for separate dedicated detection hardware and reducing overall system complexity while maintaining reliable detection capability.
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 allows for rapid and accurate detection of foreign objects, enhancing safety and enabling faster, more reliable wireless charging processes.
Implementation Method 1
connect the inductor and the capacitor to form an oscillating circuit; sample a voltage of the capacitor in the oscillating circuit formed by the inductor and the capacitor
Data Source
Figure 1~2
Figure 3
Figure 4~5b
AI summary
Embodiments of this application provide a quality factor measurement circuit and measurement method based on an oscillating circuit, and an electronic device, and relate to the field of electronic technologies, so as to obtain a Q value quickly with high precision. The quality factor measurement circuit based on an oscillating circuit includes: the oscillating circuit, a measurement control circuit, and a voltage sampling circuit, where the measurement control circuit is connected to a power supply, and the measurement control circuit is connected to the oscillating circuit; and the oscillating circuit includes an inductor and a capacitor connected in series, where a first terminal of the inductor is connected to the measurement control circuit, a second terminal of the inductor is connected to a first terminal of the capacitor, and a second terminal of the capacitor is connected to a common voltage terminal or the measurement control circuit; the measurement control circuit is configured to connect the inductor and the capacitor to the power supply in series to form a charging loop to charge the capacitor; and further configured to: connect the inductor and the capacitor to form an LC oscillating loop; or connect the inductor and the capacitor to form an LC oscillating loop, and connect a predetermined resistor in series to the LC oscillating loop; and the voltage sampling circuit is connected to the first terminal of the capacitor.