Wireless Charging Case Detection for Accurate Foreign Object Sensing
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Solution Overview
Problem
Existing wireless power transfer (WPT) systems face challenges in accurately estimating 'friendly metal' losses due to unknown parameters such as relative positioning of devices, leading to inefficiencies and potential unnecessary power delivery to foreign objects.
Innovation Solution
Incorporating a machine-readable tag, such as an NFC tag, on the case of a wireless power receiver device to provide information about its properties, including friendly metal loss modeling parameters, which are used by the controller and communication circuitry to estimate and account for these losses during foreign object detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional FOD systems estimate friendly metal losses without case information, then the system structure remains simple, but the measurement precision of loss estimation deteriorates due to unknown parameters
Solution Approach 1:
The case information including friendly metal loss modeling parameters is pre-stored in a machine readable tag attached to the case. During wireless power transfer, the transmitter interrogates this tag to obtain the parameters in advance, eliminating the need for complex real-time measurement and calculation of case-related losses.
Solution Approach 2:
A machine readable tag serves as an intermediary carrier between the case and the wireless power transmitter. The tag stores and transmits case information including friendly metal loss modeling parameters, enabling the transmitter to accurately estimate losses without direct physical contact or complex sensing of the case.
2Measurement precision
If the system interrogates machine readable tags for case information, then the measurement precision of friendly metal losses improves, but the loss of time increases due to additional interrogation steps
Solution Approach 1:
Case information including friendly metal loss modeling parameters is pre-stored in the machine readable tag during manufacturing. When the case is attached to the wireless power receiver, the information is already prepared and readily available for interrogation, eliminating the need for time-consuming measurements during power transfer.
Solution Approach 2:
The physical measurement and calculation process for determining case-related losses is replaced by electronic interrogation of the machine readable tag. This substitution reduces the time required from potentially lengthy measurement procedures to rapid electronic data retrieval.
3Reliability
If foreign object detection uses basic power loss measurement, then the device complexity remains low, but the reliability of foreign object detection deteriorates due to inaccurate friendly metal loss estimation
Solution Approach 1:
The system uses feedback from the machine readable tag to continuously update the friendly metal loss estimation. The controller compares the tag-provided parameters with actual power loss measurements, enabling accurate differentiation between case-related losses and foreign object losses, thereby improving detection reliability.
Solution Approach 2:
By pre-obtaining case information from the machine readable tag before or during power transfer initiation, the system establishes an accurate baseline for friendly metal losses. This preliminary knowledge enables more reliable foreign object detection throughout the power transfer process without requiring complex real-time analysis.
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 friendly metal loss estimation, reducing errors in detecting foreign objects and improving the efficiency of power transfer by allowing for precise control of power delivery and mitigating measures.
Implementation Method 1
a coil that couples to a corresponding coil of a counterpart device to facilitate wireless power transfer
Implementation Method 2
The machine readable tag can be an NFC tag
Data Source
AI summary
A wireless power transfer device can include a coil that couples to a corresponding coil of a counterpart device to facilitate wireless power transfer, a power converter coupled to the coil, and controller and communication circuitry that monitors one or more observable parameters associated with the wireless power transfer to detect a presence of a foreign object that is not the counterpart device and controls the power converter responsive to detection of the foreign object. The controller and communication circuitry can perform foreign object detection based on power accounting that includes estimating friendly metal losses associated with the counterpart device. The controller and communication circuitry can interrogate a machine readable tag associated with a case of the counterpart device and can receive from the machine readable tag information about the presence or properties of the case. The machine readable tag can be an NFC tag.