Wireless Charging Coil Voltage Detection for Foreign Object Heating
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Solution Overview
Problem
During wireless charging, foreign objects can cause improper heating due to magnetic field changes, posing a risk of accidents.
Innovation Solution
A foreign object detection device with a foreign object detection coil and a signal acquisition module that activates a reference voltage acquisition procedure to detect coil voltages, determining if they exceed a reference voltage, and triggers a protection procedure if they do, preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless charging is performed using electromagnetic induction, then charging efficiency is improved, but foreign objects may be improperly heated causing safety hazards
Solution Approach 1:
The patent performs foreign object detection before initiating the charging process by measuring the impedance of the charging coil. This preliminary detection identifies foreign objects in advance, preventing them from being heated during charging, thus resolving the contradiction between maintaining charging efficiency and preventing foreign object heating hazards
Solution Approach 2:
The patent implements a feedback mechanism where the controller continuously monitors coil impedance during charging and compares it against reference values. When impedance changes indicate the presence of foreign objects, the system provides feedback to stop or adjust charging, thereby preventing foreign object heating while maintaining efficient charging operation under normal conditions
2Measurement precision
If foreign object detection is performed continuously during charging, then detection accuracy is improved, but system complexity increases
Solution Approach 1:
The patent employs periodic foreign object detection at specific stages (before charging starts and at intervals during charging) rather than continuous monitoring. This periodic approach maintains adequate detection accuracy while significantly reducing system complexity and computational burden compared to continuous real-time monitoring
Solution Approach 2:
The patent uses impedance as a detection parameter that naturally changes when foreign objects are present. By monitoring this inherent electrical parameter change rather than requiring complex sensor arrays or multiple detection methods, the system achieves accurate foreign object detection with minimal additional 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 device effectively detects foreign objects, preventing damage by activating a protection procedure when coil voltages exceed the reference voltage, ensuring safe charging operations.
Implementation Method 1
The principle of wireless charging is based on electromagnetic induction. The alternating current first transmits through a coil in a charging disk (power transmitter) of the FOD (Foreign Object Detection) device to generate magnetic field changes.
Implementation Method 2
A coil of a to-be-charged device senses the magnetic field changes and generates an induced current to achieve the charging effect.
Implementation Method 3
If there are conductors (herein referred to as 'foreign objects') affected by magnetic momentum above the foreign object detection device, such magnetic materials will be improperly heated to a dangerous temperature due to changes in the magnetic field
Data Source
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AI summary
A foreign object detection device includes a foreign object detection coil, a voltage acquisition module and a controller. The voltage acquisition module is configured to activate a reference voltage acquisition procedure. The reference voltage acquisition procedure includes: when there is no to-be-charged device above the foreign object detection device, a voltage acquisition module obtains a foreign object detection reference voltage of the foreign object detection coil. The controller is configured to: when there is the to-be-charged device above the foreign object detection device, activate a first foreign object detection procedure. The first foreign object detection procedure includes: the controller obtains a coil voltage of the foreign object detection coil; the controller determines whether the coil voltage exceeds a foreign object detection voltage reference value; and, if the coil voltage of the foreign object detection coil exceeds the foreign object detection voltage reference value, the controller starts a protection procedure.