Inductive Sensing Coil for Ferromagnetic Foreign Object Detection
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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 and heating in ferromagnetic objects within the electromagnetic field, potentially causing hazards such as fires or damage.
Innovation Solution
An inductive sensing coil is used to generate a magnetic field, with a controller detecting changes in electrical characteristics caused by the presence of ferromagnetic objects, allowing for the determination of object presence and enabling safe power transfer by adjusting or halting the charging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless charging systems use electromagnetic fields to transfer power, then charging convenience is improved, but ferromagnetic objects may heat up or cause hazards
Solution Approach 1:
The system performs foreign object detection before initiating wireless power transfer by measuring the electrical characteristic of a sensing coil in the absence of a time-varying magnetic field. This preliminary detection identifies ferromagnetic objects that could heat up during charging, allowing the system to prevent hazardous conditions before they occur while maintaining charging convenience.
Solution Approach 2:
A sensing coil serves as an intermediary detection mechanism between the power transfer system and ferromagnetic objects. The coil's electrical characteristic changes in response to nearby ferromagnetic materials, providing a safe indirect method to detect potential hazards without directly exposing the system to the harmful heating effects.
2Productivity
If electromagnetic fields are applied for power transfer, then power transfer efficiency is improved, but eddy currents are induced in ferromagnetic objects causing heating
Solution Approach 1:
The system measures the sensing coil's electrical characteristic before applying the time-varying magnetic field for power transfer. This preliminary measurement detects the presence of ferromagnetic objects that would experience eddy current heating, allowing the system to maintain high power transfer efficiency only when safe operating conditions are confirmed.
3Reliability
If foreign object detection is implemented, then safety is improved, but system complexity increases
Solution Approach 1:
The sensing coil serves multiple functions: it is used for both normal power transfer operations and foreign object detection. By measuring the coil's electrical characteristic in the absence of a time-varying magnetic field, the system achieves safety detection without requiring separate dedicated detection hardware, thereby improving reliability while minimizing the increase in 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
The system effectively detects ferromagnetic foreign objects, preventing potential hazards by ensuring safe and efficient wireless power transfer to electric vehicles, reducing the risk of overheating or fires.
Implementation Method 1
an inductive sensing coil that is configurable to generate a first magnetic field
Implementation Method 2
using electromagnetic fields may induce eddy currents in a well conducting (e.g., metallic or ferromagnetic) object located within the field, potentially causing the object to heat up
Implementation Method 3
potentially causing the object to heat up
Data Source
AI summary
An apparatus for detecting a presence of an object includes an inductive sensing coil that is configurable to generate a magnetic field. The inductive sensing coil is configured to have an electrical characteristic that is detectable when generating the magnetic field. The apparatus comprises a controller configured to detect a change in the electrical characteristic and determine a presence of the object based on the detected change in the electrical characteristic.