Wireless Power Transmitter Sensing Array for Foreign Object Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High power devices require higher charging rates than conventional wireless charging systems can efficiently provide, while also facing challenges such as efficiency, metallic Foreign Object Detection (FOD), and Electromagnetic Interference (EMI).
Innovation Solution
A wireless power system that includes a sensing array with sensors to detect foreign metallic objects and a controller to manage the electromagnetic field, using a class-E amplifier and resonant capacitor to improve efficiency and EMI performance, and a transformer to adjust the resonance frequency for optimal power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher charging rates are used to charge high power devices quickly, then charging speed is improved, but efficiency and safety deteriorate due to metallic foreign object detection challenges and electromagnetic interference
Solution Approach 1:
The sensing array performs foreign object detection before power transfer begins. The controller activates sensors to scan for metallic objects in the electromagnetic field, and only initiates charging when the area is confirmed safe, preventing overheating and safety hazards before they occur
Solution Approach 2:
The sensing array continuously monitors the electromagnetic field during charging operations. When metallic objects are detected or field anomalies occur, the controller receives real-time feedback and dynamically adjusts or terminates power transfer to maintain safety while enabling high-speed charging
2Reliability
If sensing arrays are added to detect foreign metallic objects, then safety is improved, but device complexity increases
Solution Approach 1:
The sensing array serves multiple functions: detecting foreign metallic objects, mapping electromagnetic field distribution, identifying optimal power transfer zones, and monitoring charging safety. This multi-functionality reduces the need for separate systems and minimizes overall device complexity while comprehensively addressing safety concerns
Solution Approach 2:
The sensing array is integrated directly into the wireless charging system architecture, with sensors positioned between the transmitting antenna and charging surface. The controller combines sensing data with power management functions, merging detection and control operations into a unified system that reduces complexity compared to separate independent systems
3Loss of energy
If class-E amplifier and resonant capacitor are used to improve efficiency, then energy loss is reduced, but device complexity increases
Solution Approach 1:
The system employs a class-E amplifier with resonant capacitor to operate at optimized frequency and impedance parameters. By tuning the resonant frequency and adjusting circuit parameters dynamically, the system achieves maximum efficiency with minimal energy loss while managing the complexity through parameter optimization rather than additional components
4Productivity
If transformer is added to adjust resonance frequency, then power transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The transformer enables dynamic adjustment of resonance frequency based on real-time conditions. The controller modifies the transformer's operating parameters to optimize power transfer efficiency across varying loads and distances, allowing the system to adapt dynamically rather than requiring fixed-frequency operation that would limit 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
The system effectively detects and manages foreign metallic objects, enhancing efficiency and safety by reducing energy transfer and minimizing EMI, allowing for higher power charging rates in high power devices.
Implementation Method 1
a transmitting antenna configured to generate an electromagnetic field extending above the charging surface
Implementation Method 2
a receiving antenna configured to receive an electromagnetic field extending through the receiver surface
Implementation Method 3
Each sensor of the plurality of sensors is configured to generate a respective signal indicative of a strength of the electromagnetic field
Data Source
AI summary
In accordance with an embodiment, a wireless power transmitter includes a charging surface, a transmitting antenna configured to generate an electromagnetic field extending above the charging surface, a sensing array disposed between the transmitting antenna and the charging surface, and a controller coupled to the sensing array. The sensing array includes a plurality of sensors. Each sensor of the plurality of sensors is configured to generate a respective signal indicative of a strength of the electromagnetic field. The controller is configured to detect a presence of a metallic object, other than a receiving antenna of a power receiver, in the electromagnetic field based on the respective signal generated by one or more sensors of the plurality of sensors.