Inductive Thermal Sensing for Foreign Object Detection in Wireless Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless charging systems for electric vehicles face challenges in safely and efficiently transferring power due to the risk of inducing eddy currents in metallic objects, which can lead to heating and potential hazards such as fires.
Innovation Solution
The implementation of an inductive-thermal sensing method that detects foreign objects by measuring temperature changes in a sense coil, allowing for the identification of hazardous objects and adjusting power levels or shutting down the system to prevent accidents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless charging systems transfer power using electromagnetic fields, then power transfer efficiency is improved, but metallic objects may heat up due to induced eddy currents
Solution Approach 1:
The system performs foreign object detection before initiating full power transfer by applying a preliminary magnetic field and measuring temperature changes in sense coils. This preliminary action identifies metallic objects that could heat up, allowing the system to adjust or prevent power transfer to avoid harmful heating while maintaining efficient charging when safe.
Solution Approach 2:
The system continuously monitors temperature changes in sense coils during power transfer and uses this feedback to control the charging process. When temperature increases indicate the presence of metallic objects, the system adjusts power levels or shuts down to prevent harmful heating, while allowing efficient operation when no foreign objects are detected.
2Reliability
If foreign object detection is implemented using traditional methods, then safety is improved, but system complexity increases
Solution Approach 1:
The sense coils serve dual purposes: they are part of the wireless power transfer system and simultaneously function as temperature sensors for foreign object detection. This multi-functionality enables safety monitoring without adding separate complex detection hardware, reducing overall system complexity while maintaining high safety standards.
Solution Approach 2:
The system uses its own electromagnetic field and existing sense coils to perform self-diagnosis for foreign object detection. The magnetic field exposure and temperature measurement are integrated into the normal charging operation, allowing the system to monitor itself without requiring external complex detection equipment.
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
Enhances safety by automatically detecting and preventing the heating of metallic objects within the charging area, ensuring safe and efficient power transfer to electric vehicles.
Implementation Method 1
using an alternating magnetic field to expose a metallic object to be heated by eddy currents
Implementation Method 2
heated by eddy currents
Implementation Method 3
inductively detecting a temperature increase of the metallic object
Data Source
Figure 1
Figure 2
Figure 3
AI summary
This disclosure provides systems, methods and apparatus for detecting foreign objects. An apparatus for detecting a presence of an object is provided. The apparatus includes a coil configured to inductively sense a presence of an object based on an electrical characteristic of the coil that varies as a function of a temperature of the object when the object is exposed to an alternating magnetic field. The apparatus further includes a controller configured to detect a change in the electrical characteristic.