Foreign Object Detection in Wireless Power Transfer Coils
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Solution Overview
Problem
Existing foreign object detection systems in wireless power transfer systems face challenges in accurately detecting conductive objects due to dead zones and reduced magnetic flux interlinkage, leading to lower detection precision.
Innovation Solution
A foreign object detection system utilizing first and second detection coils with a selector and controller to perform both short circuit and magnetic flux interlinkage-based determination processes, improving detection precision by addressing dead zones and ensuring accurate foreign object detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single detection coil is used for foreign object detection, then the device complexity is low, but the detection precision is reduced due to dead zones and magnetic flux interlinkage issues
Solution Approach 1:
The detection system is divided into multiple detection coils (first detection coil and second detection coil) with different configurations. Each coil detects foreign objects in its specific detection region, eliminating dead zones and improving overall detection precision without requiring a single complex detection mechanism
Solution Approach 2:
The patent uses two detection coils instead of one, providing redundant detection coverage. The first detection coil detects foreign objects in its detection region, and the second detection coil detects foreign objects in its detection region, ensuring that no dead zones remain undetected
2Measurement precision
If detection coils are placed close to the power transmission coil, then the detection sensitivity increases, but the magnetic flux interlinkage with the power reception coil decreases leading to erroneous detections
Solution Approach 1:
Different detection coils are designed with different characteristics suitable for their specific detection regions. The first detection coil has its terminals connected to specific switching unit outputs, while the second detection coil has its terminals connected to different switching unit outputs, allowing each coil to optimize its detection performance in its local region
Solution Approach 2:
The switching unit dynamically connects different detection coils to the measurement unit based on operational requirements. The controller can select which detection coil to use or switch between coils, allowing the system to adapt to different operational conditions and eliminate dead zones dynamically
3Adaptability or versatility
If the power transmission coil and power reception coil are arranged with a gap, then the wireless power transfer flexibility increases, but foreign objects can enter the gap causing power feeding efficiency deterioration
Solution Approach 1:
The detection system performs foreign object detection before and during the wireless power transfer process. By detecting foreign objects in advance and continuously monitoring during operation, the system can prevent power feeding efficiency deterioration caused by foreign objects entering the gap between coils
Solution Approach 2:
The detection coils continuously monitor the magnetic field in the gap region and provide feedback to the controller. When a foreign object is detected, the controller can adjust the power transmission or alert the user, preventing efficiency loss and ensuring safe operation throughout the power transfer process
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 detection precision of foreign objects by utilizing dual detection methods, preventing erroneous detections and ensuring reliable operation even in dead zones, thereby improving the overall efficiency of wireless power transfer systems.
Implementation Method 1
determine whether there is the foreign object depending on a change in an amount of magnetic flux interlinking with the same detection coil
Implementation Method 2
A wireless power transfer system includes a power transmission coil device and a power reception coil device and realizes wireless power transmission using electromagnetic induction
Data Source
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AI summary
A foreign object detection device for a coil device including a second coil to transmit power to a first coil wirelessly or receive power from the first coil wirelessly including: a foreign object detection coil configured to be located between the first coil and the second coil; and a cover configured to cover an upper portion of the foreign object detection coil, wherein a top surface of the cover includes at least one inclined surface inclined relative to a coil plane of the second coil, and the inclined surface is inclined downward from a low sensitivity region where detection sensitivity of the foreign object detection coil is relatively lower to a high sensitivity region where the detection sensitivity of the foreign object detection coil is relatively higher.