Foreign Object Detection in Wireless Charging Systems
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Solution Overview
Problem
Wireless charging systems face the challenge of detecting conductive foreign objects proximate the transmitting coil, which can induce currents and cause overheating, potentially damaging materials and posing a burn risk to users.
Innovation Solution
A system that includes a wirelessly chargeable battery with a receiving coil and a controller configured to switch between charging and foreign object detection modes, measuring voltage and electrical characteristics to determine if a foreign object is present by comparing expected and actual electrical consumptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If wireless charging is performed using a transmitting coil, then power transfer efficiency is improved, but foreign objects proximate the coil can induce currents causing overheating and safety hazards
Solution Approach 1:
The system performs foreign object detection before initiating the charging process. The controller measures electrical characteristics (voltage, current, impedance) of the transmitting coil and compares them against predetermined thresholds or baseline values. If foreign objects are detected based on anomalous electrical characteristics, the charging process is prevented from starting, thereby eliminating the overheating hazard before it can occur.
Solution Approach 2:
The system continuously monitors electrical characteristics of the transmitting coil during charging operations. The controller adjusts charging parameters or terminates charging based on real-time feedback from the measurement circuit. This closed-loop control enables dynamic detection of foreign objects and prevents overheating by modulating the charging process in response to detected conditions.
2Measurement precision
If foreign object detection is implemented by measuring electrical characteristics of the transmitting coil, then detection accuracy is improved, but system complexity increases
Solution Approach 1:
The system uses the transmitting coil's own electrical characteristics as the detection mechanism. The controller measures voltage, current, and impedance of the coil itself, which naturally change when foreign objects are present. This self-diagnostic approach eliminates the need for separate detection sensors or additional hardware, maintaining simple system architecture while achieving accurate foreign object detection through inherent electrical property changes.
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
Effectively detects foreign objects proximate the wireless charging device, preventing overheating and ensuring user safety by disabling charging operations when a foreign object is detected.
Implementation Method 1
a receiving coil for receiving power from the wireless charging device when the receiving coil is proximate the wireless charging device
Implementation Method 2
When a conductive foreign object is positioned proximate the transmitting coil of a wireless charging system, the transmitting coil can induce a current in the foreign object that causes the foreign object to increase in temperature
Data Source
AI summary
Wireless charging systems and methods for detecting foreign objects proximate the wireless charging systems. A wireless charging system (10) includes a wirelessly chargeable battery (14) that receives power from a wireless charging device (16) when the wirelessly chargeable battery (14) is proximate the wireless charging device (16). The wireless charging device (16) determines an actual electrical consumption of the wireless charging system (10), and the wirelessly charging battery (14) measures a voltage induced in the wirelessly chargeable battery (14) by the wireless charging device (16). The wireless charging device (16), the wirelessly chargeable battery (14), or a combination of the two determines an expected electrical consumption of the wireless charging system (10) based on the measured voltage, and determines whether a foreign object (12) is proximate the wireless charging system (10) based on the expected and actual electrical consumptions.