NFC Charging Transmitter Movement Detection for Overheat Prevention
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Solution Overview
Problem
Existing wireless charging solutions using large antennas are limited in charging small-size low-power electronic devices, and NFC-based wireless charging faces risks of overheating and damage when the power receiver is moved away from the charging transmitter due to mismatched impedance and delayed detection of movement.
Innovation Solution
A charging transmitter device equipped with a detection circuit that detects movement of the power receiver relative to the transmitter and a charging control circuit to stop charging immediately upon detection, using a radiofrequency signal to anticipate and prevent high-power generation that could damage the transmitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the charging transmitter emits maximum power when the power receiver is moved away, then the charging signal power is high, but the impedance is no longer matched causing the charging transmitter to heat up and potentially be damaged
Solution Approach 1:
The patent applies preliminary action by detecting movement of the power receiver before excessive heating occurs. The detection circuit monitors the coupling between transmitter and receiver antennas, and when movement is detected (indicating the receiver is being moved away), the control circuit proactively reduces or stops power emission before the transmitter can overheat or be damaged from impedance mismatch.
2Reliability
If temperature or current measurement means are used to detect overheating, then the charging signal generation can be stopped, but the stoppage occurs at a late stage after the charging transmitter has already heated up
Solution Approach 1:
The patent uses preliminary action by detecting receiver movement through changes in antenna coupling or reflected power before excessive heat is generated. This early detection allows the system to stop charging proactively, avoiding the delayed response inherent in temperature-based detection methods that only react after overheating has already occurred.
Solution Approach 2:
The patent implements feedback by continuously monitoring the coupling between transmitter and receiver antennas during charging. The detection circuit provides real-time feedback about receiver position or presence, allowing the control circuit to adjust power emission dynamically. This feedback mechanism enables timely detection of receiver movement and immediate response to prevent overheating.
3Volume of moving object
If NFC wireless charging is used for small electronic devices, then space occupancy is reduced and antennas can be placed on printed circuit boards, but impedance matching becomes critical when receiver movement occurs
Solution Approach 1:
The patent applies dynamics by implementing a dynamic power control system that adapts to changing coupling conditions. Rather than using fixed impedance matching, the system continuously monitors antenna coupling and dynamically adjusts power emission levels based on real-time feedback about receiver presence and position, making the system adaptable to movement in compact NFC charging applications.
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 solution effectively stops charging at the first movement of the power receiver, preventing overheating and extending the service life of the charging transmitter by anticipating and stopping high-power radiofrequency signal generation.
Implementation Method 1
an antenna configured, during charging, to emit a charging radiofrequency signal and to detect a radiofrequency signal outside the charging transmitter device
Data Source
AI summary
According to one aspect, a charging transmitter device is configured to carry out near-field wireless charging of a power receiver device, the charging transmitter device comprising a charging safeguarding circuit including a detection circuit configured to detect a movement of the power receiver device relative to the charging transmitter device, and a charging control circuit configured to stop charging when a movement of the power receiver device is detected.