Foreign Object Detection in Wireless Power Systems
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Solution Overview
Problem
Existing power systems fail to effectively detect foreign objects, such as dust or moisture, in power transmission lines, leading to potential overheating, electrolysis, and damage to electronic devices due to abnormal resistance changes.
Innovation Solution
A method and system that adaptively adjust the current level from the power supplier to the receiver side by monitoring voltage differences before and after supplying power, using a pull-down resistor and pull-up circuit to determine foreign object presence and implement protective measures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high level current is continuously supplied to the electronic device, then power delivery efficiency is improved, but the connection port or transmission line may be damaged by overheat or electrolysis reaction
Solution Approach 1:
The patent applies preliminary action by performing foreign object detection before power delivery begins. The system detects foreign objects in the power transmission line by measuring resistance during a detection phase, and only proceeds with power delivery if no foreign object is present, thereby preventing overheat and electrolysis damage before they can occur.
Solution Approach 2:
The patent implements feedback by continuously monitoring the resistance in the power transmission line during operation. When a foreign object is detected or resistance changes indicate potential damage, the system provides feedback to stop or reduce power delivery, creating a closed-loop control system that prevents harmful effects while maintaining efficient power transfer under normal conditions.
2Reliability
If foreign object detection capability is added to the power system, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The patent merges the foreign object detection function with the existing power delivery control circuitry. The same controller that manages power delivery also performs resistance measurement and foreign object detection, eliminating the need for separate dedicated detection hardware and reducing overall system complexity while maintaining high detection reliability.
Solution Approach 2:
The patent applies universality by designing the power transmission line to serve multiple functions: it acts as both the power delivery path and the sensing path for foreign object detection. The existing transmission infrastructure is utilized for dual purposes, avoiding additional complex detection equipment while achieving reliable foreign object identification.
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
Prevents damage by accurately detecting foreign objects and adjusting current levels to prevent overheating and electrolysis, ensuring safe operation of power systems.
Implementation Method 1
When a foreign object (which may be a solid object such as dust or a liquid object such as moisture) or rust exists in the current loop, such as in the power transmission line or signal transmission line, or between the lines, the equivalent resistance is changed. Hence, the present invention detects whether a foreign object or rust exists, by detecting a change of the equivalent resistance
Implementation Method 2
The power supplier 10 and the electronic device 20 are coupled to each other through the cable 70. The power supplier 10 at least includes a power control switch (not shown), and the electronic device 20 at least includes a load (not shown). The cable 70 includes a positive power transmission line 71, a negative power transmission line 73, and a signal transmission line 72.
Implementation Method 3
When such an abnormal condition occurs, if the power supplier 10 continues supplying high level current to the electronic device 20, the connection port or the transmission line may be damaged by overheat, or an electrolysis reaction may be triggered to rust the connection port or the transmission line
Data Source
AI summary
A power system capable of detecting a foreign object includes a power supplier side, a power receiver side and a cable. The power supplier side includes a power control switch, a power control circuit and a pull-up circuit. The power control circuit controls the power control switch to provide a supply voltage to the power receiver side. The pull-up circuit provides a supplier transmission current to generate a supplier transmission voltage for determining whether the power supplier side and the power receiver side are coupled properly. The power control circuit determines whether a foreign object exists between the power supplier side and the power receiver side according to a voltage difference of the supplier transmission voltage before and after the supply voltage VBUS is provided. The power control circuit adaptively controls the power control switch and adjusts the transmission current according to whether a foreign object exists.