Wireless Power Transmitter Coil Sensing for Foreign Object Detection
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Solution Overview
Problem
Existing wireless power transmission systems lack an effective method to sense foreign materials on the transmitter and determine whether they are power transmission targets, leading to decreased efficiency and potential damage.
Innovation Solution
The system employs a plurality of sensing coils and a processor to sequentially apply powers to a power transmission coil, identify induction voltages in the sensing coils, and determine the presence and type of external devices based on these voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless power transmission is performed without sensing foreign materials, then power transmission speed and convenience are improved, but wireless power transmission efficiency decreases and damage may occur to the transmitter
Solution Approach 1:
The system performs foreign material sensing before initiating power transmission by sequentially applying test powers to sensing coils and measuring induction voltages. This preliminary detection prevents efficiency loss and damage by identifying foreign materials in advance, allowing the system to avoid transmitting power to inappropriate targets while maintaining fast transmission when safe.
2Measurement precision
If foreign material sensing is performed continuously, then sensing accuracy and safety are improved, but device complexity and power consumption increase
Solution Approach 1:
The system performs foreign material sensing periodically at key moments (before power transmission, during transmission intervals) rather than continuously. The processor sequentially applies test powers to multiple sensing coils at discrete time points and compares induction voltages to reference values, achieving accurate detection while minimizing complexity and power consumption through timed, intermittent measurements.
3Measurement precision
If multiple sensing coils are used to improve sensing coverage, then sensing accuracy is improved, but device complexity increases
Solution Approach 1:
The sensing system is divided into multiple independent sensing coils arranged in different positions and orientations. Each coil independently contributes to detecting foreign materials in its specific zone, providing comprehensive coverage. The processor sequentially activates each coil and evaluates its induction voltage separately, achieving high sensing accuracy through distributed detection without requiring a single complex sensing mechanism.
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 allows for accurate sensing of external devices, preventing efficiency decreases and damage by appropriately determining the type of device and adjusting power transmission accordingly.
Implementation Method 1
an alternating magnetic field is generated around a coil included in a wireless power transmitter by an alternating current (AC) current flowing in the coil, and an eddy current is formed in a heating target according to Faraday's law by the alternating magnetic field
Implementation Method 2
an eddy current is formed in a heating target according to Faraday's law by the alternating magnetic field. Resistance to this eddy current causes heat
Data Source
AI summary
Disclosed is an electronic device including a plurality of sensing coils for sensing an external device; a power transmitting coil for transmitting power to the external device; and a processor configured to: sequentially apply, to the power transmitting coil, powers having magnitudes respectively set to correspond to the plurality of sensing coils, and during a period in which power corresponding to each sensing coil of the plurality of sensing coils among the powers is applied, identify induction voltages respectively induced in the plurality of sensing coils, and sense the external device located on a wireless power transmitting device, on the basis of the identified induction voltages.