Foreign Object Detection Circuit for Wireless Power
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Solution Overview
Problem
Conventional foreign object detection methods in power supply systems are time-consuming as they require waiting for a voltage level to reach a steady state before determining the presence of a foreign object, which delays detection.
Innovation Solution
A foreign object detection method that discharges a capacitor via a function pin, provides a sensing current to charge it, and senses voltage variations over a predetermined period to determine if a foreign object exists, using a discharging circuit, current source circuit, and foreign object detection circuit to compare voltage variations with predetermined thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the conventional method waits for the voltage level to reach a steady state before determining foreign object presence, then the detection accuracy is improved, but the detection time increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor to a known voltage level before the actual detection process. This preparation step allows the system to immediately begin measuring voltage variations when a foreign object is introduced, eliminating the need to wait for steady state voltage establishment. The capacitor is charged in advance through a control circuit that sets a predetermined voltage, enabling rapid detection without sacrificing measurement accuracy.
2Reliability
If the system uses a comparator to compare voltage level with reference voltage, then the detection reliability is improved, but the system complexity increases
Solution Approach 1:
The patent introduces a capacitor as an intermediary element between the power supply and the comparator. This capacitor serves as a buffer that stores electrical charge and enables voltage variation detection without requiring direct continuous monitoring of the power supply voltage. The intermediary capacitor simplifies the detection mechanism by converting complex voltage level comparisons into simpler voltage variation measurements, thereby maintaining detection reliability while reducing overall system complexity.
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 rapid detection of foreign objects without waiting for a steady state voltage, allowing for quick identification within a short period, typically less than 100 milliseconds.
Implementation Method 1
a capacitor, wherein the switch is configured to operably discharge the capacitor via the function pin
Implementation Method 2
providing a sensing current flowing through the function pin, to charge the capacitor
Data Source
AI summary
A foreign object detection method for detecting whether a foreign object exists on a function pin of a power supplier side or a power receiver side, wherein the power supplier side and the power receiver side are coupled to each other in a detachable fashion. The foreign object detection method includes: discharging a capacitor via the function pin, wherein the capacitor is electrically connected to the function pin; providing a sensing current flowing through the function pin, to charge the capacitor; sensing a voltage variation of the function pin during a predetermined period; and comparing the voltage variation with a predetermined variation, so as to determine whether a foreign object exists on the function pin.