Wireless Charging Foreign Object Detection Using Segmented Coils
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Solution Overview
Problem
Current wireless charging systems face inefficiencies and increased costs due to the complexity of foreign object detection, particularly the induced voltage method, which requires equal magnetic fluxes through detection coils and suffers from blind spots, necessitating complex coil structures and high costs to mitigate these issues.
Innovation Solution
A foreign object detection apparatus using two or three detection coils and an excitation coil, where the coils are arranged to ensure equal induced voltages under normal conditions, allowing for the detection of foreign objects by comparing voltages generated in the time-varying magnetic field, thereby eliminating blind spots and simplifying the coil structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the induced voltage method is used for foreign object detection, then detection precision can be adjusted by adjusting the size of the detection coil, but the detection coil has a detection blind spot and requires complex multi-layer staggered coils to eliminate blind spots, significantly increasing system complexity and cost
Solution Approach 1:
The detection system is segmented into multiple detection coils with different areas (first detection coil with smaller area, second detection coil with larger area). Each coil is responsible for detecting foreign objects in its specific detection range, and by segmenting the detection task across multiple coils with different characteristics, the system eliminates blind spots without requiring complex multi-layer staggered arrangements
Solution Approach 2:
Different detection coils are designed with different local qualities (different areas and detection ranges). The first detection coil covers a smaller area while the second covers a larger area, creating complementary detection zones. This local differentiation allows each coil to optimize for its specific detection range, eliminating the need for uniform complex multi-layer structures
2Measurement precision
If equal magnetic fluxes through detection coils are required to ensure detection precision, then detection accuracy is improved, but the detection coils need to be precisely processed and the detection system becomes relatively complex
Solution Approach 1:
Instead of requiring equal magnetic fluxes through all detection coils, the system changes the parameter approach by using detection coils with different areas and different numbers of turns. The product of turns and area is kept equal (N1×S1=N2×S2) to maintain equal induced voltages under normal conditions, but this is achieved through parameter design rather than precise flux control, simplifying the system
Solution Approach 2:
The conventional approach requires equal fluxes through coils, but this invention inverts the approach: it allows different fluxes through different area coils while maintaining equal induced voltages by adjusting the number of turns proportionally. This inversion simplifies the requirement from flux control to a simpler turns-area product relationship
3Reliability
If multi-layer staggered detection coils are laid to eliminate detection blind spots, then blind spots are eliminated, but costs of the detection system are significantly increased
Solution Approach 1:
The detection system is divided into multiple coils with different areas working in parallel on the same plane. This segmentation approach eliminates blind spots by ensuring comprehensive coverage through the combination of different detection ranges, without requiring the costly multi-layer staggered configuration
Solution Approach 2:
Instead of adding layers (vertical dimension) to eliminate blind spots, the invention uses another approach: placing multiple coils with different areas on the same plane (horizontal dimension). This dimensional shift achieves complete coverage without increasing system layers, reducing complexity and cost
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 effectively detects foreign objects without blind spots, reducing system complexity and costs, while ensuring accurate detection of metal objects that could otherwise cause inefficiencies or damage in wireless charging systems.
Implementation Method 1
Both of the two technical solutions are based on an electromagnetic induction principle. A high-frequency magnetic field is generated through a high-frequency alternating current of a transmitter coil
Implementation Method 2
A principle of the induced voltage method is to place a detection coil in the high-frequency magnetic field, and determine whether an induced voltage of the detection coil is abnormal
Implementation Method 3
because metal has an eddy current effect in a time-varying magnetic field, an induced eddy current is generated inside the metal
Data Source
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AI summary
This application provides a wireless charging foreign object detection apparatus, applied to the field of wireless charging technologies. The detection apparatus includes: an excitation coil configured to provide a time-varying magnetic field, detection coils configured to detect a foreign object, and a processor configured to determine whether a foreign object exists. The detection coils may include two detection coils, or may include at least three detection coils. The at least three detection coils may be further configured to eliminate a detection blind spot.