Wireless Power Receiver Abnormal State Detection Circuit
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Solution Overview
Problem
Existing wireless power supply systems face challenges in detecting abnormal states, such as foreign objects or misalignment between coils, which lead to power loss and heating issues, requiring comparison of transmitted and received power for detection.
Innovation Solution
A power receiving apparatus that detects abnormal states based on relative changes in received power, allowing for precise detection without requiring high precision in measuring absolute values of transmitted and received power, and includes a control circuit for adjusting sensitivity and communicating with the transmission apparatus to suspend power supply when an abnormal state is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If foreign object detection is performed by comparing transmitted and received power, then detection capability is provided, but the system requires high precision measurement of absolute power values and complex coordination between transmission and reception apparatus
Solution Approach 1:
The power receiving apparatus independently performs abnormal state detection by monitoring changes in received power during power reception, without requiring coordination with or data from the power transmission apparatus. The control circuit detects abnormal states autonomously based on power changes exceeding a threshold, eliminating the need for complex inter-apparatus communication and high-precision absolute power measurement.
Solution Approach 2:
The foreign object detection function is extracted from the transmission apparatus and relocated to the reception apparatus. This separates the detection responsibility from the transmission side, allowing the reception apparatus to independently monitor its own power reception status and detect abnormalities without relying on transmitted power data or complex system-wide coordination.
2Measurement precision
If absolute power values are measured with high precision, then detection accuracy is improved, but measurement system complexity and cost increase
Solution Approach 1:
The detection approach changes from measuring absolute power values to detecting relative changes in received power. The control circuit monitors variations in power reception over time and detects abnormal states when changes exceed a predetermined threshold, eliminating the need for high-precision absolute power measurement instruments and reducing measurement system complexity.
Solution Approach 2:
Instead of measuring absolute power values with high precision across the entire range, the system only needs to detect significant changes or deviations from normal power reception levels. This partial measurement approach focuses on detecting abnormal variations rather than characterizing the complete power state, reducing measurement requirements.
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
Enables stable and precise abnormal state detection by the power receiving apparatus itself, improving detection speed and precision, and allowing the system to operate without relying on the transmission apparatus for foreign object detection.
Implementation Method 1
The wireless power supply that conforms to the Qi standard uses electromagnetic induction between a transmission coil and a reception coil
Implementation Method 2
The rectifier circuit 34 and the smoothing capacitor 36 rectify and smooth a current S4 induced at the reception coil 32 according to the electric power signal S2, thereby converting the current S4 into a DC voltage
Data Source
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AI summary
A control circuit 400 is employed for controlling a wireless power receiving apparatus 300 that receives an electric power signal from a wireless power transmission apparatus. An electric power detection unit 402 detects the received electric power PRX received by the wireless power receiving apparatus 300. A control unit 404 generates a control signal CE for controlling the electric power PTX to be transmitted by the wireless power transmission apparatus. When the received electric power PRX detected by the electric power detection unit 402 falls despite the control signal CE not indicating an instruction to lower the electric power PTX to be transmitted, an abnormal state judgment unit 406 judges that an abnormal state has occurred.