Wireless Charging Foreign Object Detection via Oscillation Sampling
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Solution Overview
Problem
Existing wireless charging systems face inaccuracies in detecting foreign objects due to noise interference and value deviations in calculating the Q factor, leading to potential damage from metal objects.
Innovation Solution
A method involving temporary interruption of electricity signal transmission to sample oscillation waveforms, perform integral operations, and calculate integrated average values and oscillation frequencies to accurately detect foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Q factor calculation method is used to detect foreign objects, then the detection can be performed, but the accuracy is reduced due to noise interference and value deviations
Solution Approach 1:
The patent applies preliminary action by temporarily interrupting the power transmission before performing the Q factor measurement. This interruption isolates the measurement process from the ongoing power transfer, preventing noise and interference from affecting the measurement accuracy. The system captures the oscillation waveform during this brief interruption period, ensuring a clean measurement environment that eliminates the harmful effects of active power transmission on detection reliability.
2Productivity
If power transmission is continuous, then the wireless charging efficiency is maintained, but foreign object detection accuracy deteriorates due to noise and interference
Solution Approach 1:
The patent implements periodic action by introducing brief, periodic interruptions in the power transmission cycle. These interruptions occur at predetermined intervals to capture oscillation waveforms for foreign object detection. The system balances the duration of transmission and interruption, ensuring that detection accuracy is improved without significantly reducing overall charging efficiency. This periodic measurement approach allows the system to maintain productivity while periodically verifying safety conditions.
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
Improves the accuracy of foreign object detection by reducing the impact of noise and value deviations, effectively preventing damage from metal objects during wireless power transfer.
Implementation Method 1
a coil of the power transmitter has an oscillation frequency as the same as or similar to that of the coil of the power receiver such that they can be effectively coupled to each other
Implementation Method 2
If a metal object is placed close to the power transmitter and receiver during the power transmitter supplies power to the power receiver, the power transmitter, the power receiver and the metal object may be damaged by the heat generated by the metal object
Data Source
AI summary
A method of foreign object detecting during wireless power transfer and a power transmitter are provided. The power transmitter includes: a control circuit, configured to temporarily interrupt transmission of an electricity signal; a signal sampling circuit, configured to sample, during the transmission of the electricity signal is temporarily interrupted, a signal generated by an oscillation circuit of the power transmitter; the control circuit is further configured to: obtain an oscillation waveform based on sampled values; perform an integral operation on the oscillation waveform and average the result of the integral operation to obtain an integrated average value; obtain an oscillation frequency of the oscillation waveform; and determine whether there is a foreign object based on the integrated average value and the oscillation frequency. The power transmitter can effectively improve the accuracy of determining whether there is a foreign object approaching the power transmitter during the wireless power transfer.