Wireless Charging Coil Array Foreign Object Detection
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Solution Overview
Problem
Wireless charging systems face challenges in accurately distinguishing between compatible devices and foreign objects, leading to potential undesirable heating of metallic objects during power transmission.
Innovation Solution
The system employs signal measurement circuitry and control circuitry to analyze inductance and other measurements from a coil array, using image-processing-based and machine-learning-based foreign object detection to identify valid segments corresponding to wireless power receiving devices, and compares these with received device-identifiers to determine if foreign objects are present, thereby controlling wireless power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless power transmission is performed using a coil array, then power transmission efficiency is improved, but foreign objects may be heated causing safety issues
Solution Approach 1:
The system performs foreign object detection by analyzing inductance measurements before initiating wireless power transmission. The control circuitry identifies segments with abnormal inductance values that indicate foreign objects, and prevents power transmission to those segments, thereby avoiding foreign object heating while maintaining efficient power transmission to safe segments
2Object-affected harmful factors
If foreign object detection is performed using inductance measurements, then safety is improved, but device complexity increases
Solution Approach 1:
The wireless power receiving device performs self-detection by measuring the inductance of each coil in the array and automatically identifying segments with foreign objects. The device uses its own measurement circuitry and control logic to detect foreign objects and prevent power transmission to affected segments, eliminating the need for separate complex external detection systems
3Speed
If the entire coil array is used for power transmission, then power transmission speed is improved, but foreign object detection capability deteriorates
Solution Approach 1:
The coil array is divided into multiple independent segments, each with its own inductance measurement capability. The control circuitry measures inductance for each segment individually and identifies segments containing foreign objects based on abnormal inductance values. Power transmission is then performed only on segments without foreign objects, maintaining both detection capability and transmission speed
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 effectively prevents undesirable heating of foreign objects by accurately differentiating between compatible devices and incompatible objects, ensuring safe and efficient wireless power transfer.
Implementation Method 1
a wireless power receiving device that is located on a charging surface of a wireless power transmitting device. The wireless power receiving device has a wireless power receiving coil and the wireless power transmitting device has a wireless power transmitting coil array. Control circuitry may use inverter circuitry in the wireless power transmitting device to supply alternating-current signals to coils in the coil array, thereby transmitting wireless power signals.
Implementation Method 2
Signal measurement circuitry coupled to the coil array may make measurements while the control circuitry uses the inverter circuitry to apply excitation signals to each of the coils. The control circuitry can analyze measurements made with the signal measurement circuitry to determine the values of inductances and other measurements associated with the coils in the coil array.
Implementation Method 3
Foreign objects on the coil array such as metallic objects without wireless power receiving coils can be detected using image-processing-based foreign object detection. For example, control circuitry may use inductance measurements and other measurements from the coils in the coil array to identify valid segments of the coil array that correspond to potential wireless power receiving devices.
Data Source
AI summary
A wireless power transmission system has a wireless power receiving device with a wireless power receiving coil that is located on a charging surface of a wireless power transmitting device with a wireless power transmitting coil array. Control circuitry in the wireless power transmitting device may use inverter circuitry to supply alternating-current signals to coils in the coil array, thereby transmitting wireless power signals. The control circuitry may also be used to detect foreign objects on the coil array such as metallic objects without wireless power receiving coils. For example, control circuitry may use inductance measurements from the coils in the coil array to identify segments of the coil array that correspond to potential wireless power receiving devices. The control circuitry may control wireless power transmission based on a comparison between the number of identified segments corresponding to potential wireless power receiving devices and a number of received device-identifiers.