Foreign Matter Detection in Wireless Power Transfer Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional foreign matter detection devices in non-contact power supply systems face challenges in detecting foreign matter due to the large inductance of power supply coils, which results in a small change in magnetic flux, making it difficult to detect foreign objects, especially in high-power applications like automobiles.
Innovation Solution
The foreign matter detection device incorporates a separate magnetic field generation unit that generates a magnetic field for the sensor coil, independent of the power supply and reception units, allowing for high sensitivity detection without relying on an external magnetic field environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power supply coils with large inductance are used in high-power non-contact power supply systems, then power transmission capability is improved, but foreign matter detection sensitivity deteriorates due to small magnetic flux changes
Solution Approach 1:
The patent segments the magnetic field generation function into two separate sources: the power supply coil for power transmission and a dedicated detection coil for foreign matter detection. This segmentation allows each coil to be optimized for its specific function, resolving the contradiction between power transmission capability and detection sensitivity
Solution Approach 2:
The patent introduces a detection coil as an intermediary element that specifically generates magnetic flux for foreign matter detection purposes. This intermediary coil enables sensitive detection without compromising the power transmission function of the main power supply coil
2Device complexity
If detection relies on magnetic flux from power supply and reception coils, then system complexity is reduced, but detection sensitivity becomes dependent on external magnetic field environment
Solution Approach 1:
The detection coil serves multiple functions: it generates magnetic flux for foreign matter detection and its signal is processed through the existing sensor coil and control circuitry. This multi-functionality approach enables independent detection capability while utilizing existing system components
Solution Approach 2:
The detection coil creates its own magnetic field environment for detection purposes, making the detection system self-sufficient and independent of external magnetic field conditions. The system serves its own detection needs without relying on the magnetic flux from power transmission coils
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
This solution enhances the detection sensitivity of foreign matter, enabling accurate detection of both conductive and insulative foreign objects, even in regions with low magnetic flux, thereby improving safety and reliability in non-contact power supply systems.
Implementation Method 1
a magnetic field generation unit that generates a magnetic field
Implementation Method 2
presence of foreign matter is determined by detecting an electrical change in the sensing coil that due to the foreign matter
Implementation Method 3
foreign matter such as a metal or a magnetic substance may be heated due to magnetic flux passing through the foreign matter
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
A foreign matter detection device is mounted on a non-contact power supply system that supplies power in a non-contact manner from a power supply unit to a power reception unit. The foreign matter detection device includes a magnetic field sensor and a magnetic field generation unit. The magnetic field sensor detects an amount of magnetic flux that changes due to foreign matter existing between the power supply unit and the power reception unit. The magnetic field generation unit is provided separately from the power supply unit and the power reception unit, includes a magnetic field generation coil unit, and generates a magnetic field for driving the magnetic field sensor.