Heat-Sensitive And Inductive Foreign Object Detection In Wireless Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless charging systems face challenges in detecting foreign objects, which can heat up and potentially damage the transmitter due to eddy current and hysteresis effects, especially when flux density levels exceed critical levels, and existing detection methods may be costly or ineffective for small objects.
Innovation Solution
A foreign object detection system combining heat sensitive materials that change properties with temperature and inductive sensing using sense coils, where a controller determines the presence of foreign objects based on changes in these properties or electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If foreign object detection is performed using conventional methods, then detection capability is limited, but system cost increases or detection effectiveness decreases for small objects
Solution Approach 1:
The patent combines heat sensitive material detection with inductive sensing using sense coils into a unified foreign object detection system. The heat sensitive material changes its electrical characteristic in response to temperature changes caused by foreign objects, while the inductive sensing system detects changes in electrical characteristics of the sense coils, providing complementary detection mechanisms that work together to improve overall detection capability without proportionally increasing system complexity
Solution Approach 2:
The heat sensitive material acts as an intermediary between the wireless power transfer field and the detection system. When a foreign object is present, it heats the heat sensitive material, which in turn changes its electrical characteristic, allowing the controller to detect the foreign object's presence through this intermediate thermal and electrical response mechanism
2Productivity
If wireless power transfer operates at high flux density levels, then power transfer efficiency improves, but foreign objects heat up to dangerous temperatures
Solution Approach 1:
The system performs foreign object detection before initiating high-power wireless power transfer and continuously monitors during operation. The heat sensitive material and inductive sensing system detect the presence of foreign objects in advance, allowing the controller to prevent or reduce power transfer before dangerous heating occurs, thus maintaining safe operation while enabling efficient power transfer when no foreign objects are present
Solution Approach 2:
The detection system provides continuous feedback to the controller about the presence of foreign objects. When foreign objects are detected through changes in the heat sensitive material's electrical characteristic or changes in the sense coils' electrical characteristics, the controller adjusts or terminates power transfer to prevent excessive heating, creating a closed-loop control system that balances power transfer efficiency with safety
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
Effectively detects foreign objects, preventing damage to the wireless power transfer system by identifying changes in heat sensitive materials and electrical characteristics, allowing for appropriate actions such as reducing power or alerting users to remove the object.
Implementation Method 1
a heat sensing system including a heat sensitive material having a property configured to change as a function of temperature
Implementation Method 2
an inductive sensing system including one or more sense coils, wherein a change in an electrical characteristic of the one or more sense coils is indicative of presence of a foreign object
Implementation Method 3
it may reach high temperatures (e.g., over 200 degrees C), for example due to eddy current and hysteresis effects caused by the wireless charging field
Implementation Method 4
it may reach high temperatures (e.g., over 200 degrees C), for example due to eddy current and hysteresis effects caused by the wireless charging field
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In certain aspects, a method and apparatus for detecting foreign objects using heat sensitive material and inductive sensing is disclosed. In certain aspects, a foreign object detection system includes a heat sensing system comprising a heat sensitive material having a property configured to change as a function of temperature. The foreign object detection system further includes an inductive sensing system comprising one or more sense coils, wherein a change in an electrical characteristic of the one or more sense coils is indicative of presence of a foreign object. The foreign object detection system further includes a controller coupled to the heat sensing system and the inductive sensing system, wherein the controller is configured to determine presence of the foreign object based on at least one of a measure of the property of the heat sensitive material or a measure of the electrical characteristic of the one or more sense coils.