Wireless Power Feeding Foreign Substance Detection
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Solution Overview
Problem
Existing wireless power feeding systems face challenges in accurately detecting foreign substances in magnetic fields due to fluctuations in electric characteristic values like the Q factor, which are influenced by the quantity of conductors in the power receiving apparatus, making it difficult to set appropriate thresholds for detection across various types of apparatuses.
Innovation Solution
A power feeding apparatus and method that includes a power feeding unit, a measuring unit, and a foreign substance detection unit, which sets and compares a threshold value based on the quantity of conductors in the power receiving apparatus, using measurement values from electric characteristic changes to accurately detect foreign substances in the magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed threshold is used for foreign substance detection based on electric characteristic values, then the detection method is simple, but the detection accuracy deteriorates due to variations in conductor quantity across different power receiving apparatus types
Solution Approach 1:
The patent implements dynamic threshold adjustment by detecting the type of power receiving apparatus and selecting appropriate threshold values from multiple predetermined thresholds. This allows the foreign substance detection system to adapt to different conductor quantities in various apparatus types, resolving the contradiction between simple detection methods and accurate detection across diverse devices.
Solution Approach 2:
The system changes the detection parameter (threshold value) based on the detected type of power receiving apparatus. By storing multiple predetermined thresholds corresponding to different apparatus types and selecting the appropriate threshold based on apparatus type detection, the system maintains high detection accuracy across different conductor quantities without increasing overall system complexity.
2Measurement precision
If the threshold is adjusted for each type of power receiving apparatus, then detection accuracy improves, but the system complexity increases due to multiple threshold settings
Solution Approach 1:
The patent applies preliminary action by pre-storing multiple predetermined thresholds in the power feeding apparatus, each corresponding to a specific type of power receiving apparatus. This preparation is done in advance, so when a particular apparatus type is detected, the appropriate threshold is already available for immediate use, improving detection accuracy without adding operational complexity.
Solution Approach 2:
The system achieves universality by creating a detection framework that handles multiple apparatus types through a single unified process. The power feeding apparatus maintains a set of predetermined thresholds that can serve any apparatus type, and the detection mechanism universally applies the same logic of selecting and comparing against the appropriate threshold, thereby managing complexity efficiently.
3Use of energy by moving object
If electromagnetic induction system is used for wireless power feeding, then power feeding efficiency is high, but heat generation from foreign substances becomes a serious safety problem
Solution Approach 1:
The patent converts the harmful effect of foreign substances (which alter electric characteristic values) into a beneficial detection mechanism. By monitoring changes in electric characteristic values such as impedance or Q-factor, the system detects the presence of foreign substances and can prevent or mitigate heat generation, thus transforming a safety hazard into a detection opportunity while maintaining high power feeding efficiency.
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
Enables accurate detection of foreign substances in magnetic fields, preventing heat generation and ensuring safe operation by setting appropriate threshold values tailored to the specific power receiving apparatus, thereby improving the reliability of wireless power feeding systems.
Implementation Method 1
a power feeding unit configured to supply electric power to a power receiving apparatus through a magnetic field
Implementation Method 2
when a foreign substance of a conductor (such as metal) enters into the magnetic field, an eddy current may flow through the foreign substance and the foreign substance may generate heat
Data Source
AI summary
A power feeding apparatus is provided. The power feeding apparatus includes a power feeding unit configured to supply electric power to a power receiving apparatus through a magnetic field; a measuring unit configured to measure an electric characteristic value and to generate a measurement value; a power receiving unit configured to provide a set value; and a foreign substance detection unit configured to detect a foreign substance in the magnetic field based on the set value and the measurement value. A power receiving apparatus, a power feeding system, and a method of controlling power feeding are also provided.