Wireless Charging FOD Using Peak Frequency and Resonant Thresholds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wireless charging systems face challenges in accurately detecting foreign objects, which can lead to reduced charging efficiency, overheating, and potential damage due to increased ambient temperature, resulting in power waste and equipment damage.
Innovation Solution
A method and apparatus for detecting foreign objects in wireless charging systems by measuring quality factor and inductance values of a resonant circuit before the ping phase, determining threshold values based on reference factors, and dynamically adjusting these thresholds using weights that increase with reference quality factor values, and comparing measured values with determined thresholds to accurately identify foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If wireless power transmission is performed using electromagnetic induction or resonance, then power can be transferred wirelessly to devices, but foreign objects in the charging area may be heated due to induced electromagnetic signals
Solution Approach 1:
The system performs foreign object detection before initiating full wireless power transmission by measuring quality factor and inductance values during a preliminary detection phase. This preliminary action identifies potential foreign objects that could be heated, allowing the system to prevent power transmission to areas with foreign objects present
Solution Approach 2:
The system continuously monitors quality factor and inductance values during charging operations and compares them against threshold values. When deviations indicate foreign object presence, the system provides feedback to adjust or terminate power transmission, preventing foreign object heating while maintaining efficient wireless charging when safe
2Reliability
If foreign object detection sensitivity is increased to prevent heating, then safety improves, but false detections may reduce charging availability
Solution Approach 1:
The system dynamically adjusts detection threshold values based on reference quality factor and inductance values obtained during device identification. By adapting thresholds to specific receiver characteristics rather than using fixed values, the system achieves high detection sensitivity while minimizing false positives that would reduce charging availability
Solution Approach 2:
The detection system transitions from static threshold comparison to dynamic threshold adjustment based on real-time measurements of quality factor and inductance. The system adapts its detection criteria during different charging phases and based on receiver characteristics, maintaining high reliability while preserving charging productivity
3Measurement precision
If quality factor and inductance measurements are performed continuously to improve detection accuracy, then foreign object identification improves, but energy consumption and system complexity increase
Solution Approach 1:
The detection process is segmented into distinct phases: initial quality factor measurement, inductance measurement, threshold determination, and foreign object detection. Each phase performs specific measurements and comparisons, reducing the need for continuous full-parameter monitoring and simplifying the overall system architecture while maintaining high detection precision
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 approach enhances the accuracy of foreign object detection, minimizing power waste and equipment damage by effectively identifying and removing foreign objects, thereby improving charging efficiency and safety.
Implementation Method 1
The electromagnetic resonance method uses an electric field or a magnetic field instead of using electromagnetic waves or current
Implementation Method 2
The magnetic induction method uses a phenomenon that, when two coils are located adjacent to each other and then current is applied to one coil, a magnetic flux is generated to cause an electromotive force in the other coil
Implementation Method 3
If a conductor which is not a wireless power receiver, that is, a foreign object (FO), is present in a wireless charging area, an electromagnetic signal received from a wireless power transmitter may be induced in the FO, thereby increasing in temperature
Data Source
AI summary
A wireless power transmitter that transmits power to a wireless power receiver, the wireless power transmitter including a communication unit configured to communicate with the wireless power receiver; and a controller, wherein the communication unit receives a plurality of packets including a foreign object detection (FOD) status packet from the wireless power receiver, wherein the controller determines whether a foreign object is present in a charging area of the wireless power transmitter on the basis of the FOD status packet, wherein the communication unit transmits, to the wireless power receiver, a response signal indicating whether the foreign object is present in the charging area of the wireless power transmitter on the basis of a result of the determination, wherein the response signal is determined using a measured peak frequency of a power signal transmitted by the wireless power transmitter and a reference peak frequency included in the FOD status packet received from the wireless power receiver, and wherein the plurality of packets further include at least one of a signal strength packet, an end power transfer packet, a power control hold-off packet, a configuration packet, an identification packet for transmitting receiver identification information, an extended identification packet, a general request packet, a special request packet, a control error packet, a renegotiation packet, a 24-bit received power packet, an eight-bit received power packet, and a charging status packet.