Wireless Power Transmitter Q-Factor Sensing for Foreign Object Detection
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Solution Overview
Problem
Current wireless power transfer systems face challenges in accurately measuring the quality factor (Q factor) of wireless power transmitters and detecting objects or foreign matter within their operating space, which affects efficient power transfer and receiver safety.
Innovation Solution
A method where the wireless power transmitter temporarily stops power transmission to the primary coil, allowing for the measurement of the quality factor based on changes in voltage or current, enabling more accurate detection of objects and foreign substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous power transmission is maintained for efficient wireless power transfer, then power transfer efficiency is improved, but quality factor measurement accuracy deteriorates
Solution Approach 1:
The system implements periodic quality factor measurements by temporarily suspending power transmission at predetermined intervals during the wireless power transfer process. This allows the quality factor to be measured at multiple time points without continuously interrupting power transmission, thereby maintaining overall power transfer efficiency while obtaining accurate quality factor data for monitoring system state changes.
2Measurement precision
If quality factor measurement is performed by interrupting power transmission, then measurement accuracy is improved, but power transfer efficiency deteriorates
Solution Approach 1:
Instead of continuously interrupting power transmission for quality factor measurements, the system performs measurements periodically at predetermined time intervals during the power transfer process. This minimizes the total interruption time while ensuring quality factor is monitored at multiple stages, thus maintaining high power transfer efficiency while achieving accurate measurement.
Solution Approach 2:
The system measures quality factor in advance at the beginning of power transfer and at predetermined intervals thereafter. This preliminary and periodic measurement approach allows the system to establish a baseline quality factor and detect changes over time without requiring continuous measurement interruptions, thereby maintaining efficiency while ensuring measurement accuracy.
3Measurement precision
If quality factor measurement is performed continuously, then measurement accuracy is improved, but system complexity and power loss increase
Solution Approach 1:
The system performs quality factor measurements periodically at predetermined intervals rather than continuously. This reduces the complexity of the measurement system and minimizes power loss during measurements, while still providing sufficient data points to monitor quality factor changes and detect foreign objects or system state changes throughout the power transfer process.
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 quality factor measurement and foreign object detection, ensuring safer and more efficient wireless power transfer operations.
Implementation Method 1
The magnetic induction method corresponds to a method transmitting power by using electric currents that are induced to the coil of the receiver by a magnetic field, which is generated from a coil battery cell of the transmitter, in accordance with an electromagnetic coupling between a transmitting coil and a receiving coil
Implementation Method 2
The magnetic resonance method is similar to the magnetic induction method in that is uses a magnetic field. However, the magnetic resonance method is different from the magnetic induction method in that energy is transmitted due to a concentration of magnetic fields on both a transmitting end and a receiving end, which is caused by the generated resonance
Data Source
AI summary
A wireless power transmitting device according to an embodiment of the present specification relates to a wireless power transmitting device for transmitting wireless power to a wireless power receiving device, and comprises: a power conversion circuit including a primary coil for transmitting the wireless power to the wireless power receiving device; and a communication/control circuit for communicating with the wireless power receiving device and controlling the power conversion circuit, wherein, before transmitting the wireless power to the wireless power receiving device, the communication/control circuit temporarily applies driving power to the primary coil and then stops the transmission of the driving power, and obtains a quality factor on the basis of a change in the voltage or current of the primary coil during a period of time in which the transmission of the driving power is stopped.