Wireless Power Coil Control for Stop-Period Object Detection
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Solution Overview
Problem
The WPC standard for wireless power transmission does not allow for object detection during the power transmission and reception stop period, leading to inefficiencies and potential damage to NFC tags, as it cannot determine the state of the power receiving device without communication during this time.
Innovation Solution
A power transmission device with multiple coils that can detect objects using a detection process during the stop period by receiving a request from the power receiving device, allowing for the use of a specific power transmission coil for object detection, even when power is not being transmitted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If power transmission and reception are stopped during the stop period to allow NFC tag detection, then NFC tag safety is improved, but object detection capability deteriorates
Solution Approach 1:
The system segments the detection function by assigning different detection tasks to different coils: the first coil performs object detection during power transmission, while the second coil performs object detection during the stop period. This segmentation allows both functions to coexist without interference, resolving the contradiction between NFC tag safety and object detection capability.
2Reliability
If the power transmission device waits until the end of the stop period to detect object state, then communication protocol compliance is improved, but response time deteriorates
Solution Approach 1:
The system performs preliminary object detection during the stop period using the second coil before the stop period ends. This preliminary action allows the device to detect object state changes (such as power receiving device removal) during the stop period while still complying with the communication protocol, thereby reducing detection response time without sacrificing protocol compliance.
3Measurement precision
If analog ping is transmitted during the stop period to detect object state, then detection accuracy is improved, but energy consumption increases
Solution Approach 1:
The system applies local quality by using different detection methods for different time periods: during power transmission, continuous object detection is performed; during the stop period, analog ping transmission is used specifically for object detection. This localized approach ensures detection accuracy during the stop period while minimizing overall energy consumption by only activating detection during necessary periods.
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
Enables accurate detection of the power receiving device's state during the stop period, enhancing safety and efficiency by allowing for immediate restart or adjustment of power transmission, preventing potential damage and ensuring reliable charging.
Implementation Method 1
power transmission and reception and control communication therefor are performed by magnetic induction
Implementation Method 2
An NFC tag does not have a battery and is driven using energy of electromagnetic waves transmitted from a communication partner during communication
Data Source
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AI summary
Provided is a power transmission device including: a plurality of power transmission coils; a power transmission means for wirelessly transmitting power to a power receiving device using at least one of the plurality of power transmission coils; a detection means for performing a process of detecting an object using at least one of the plurality of power transmission coils; and a reception means for receiving a signal from the power receiving device, wherein, in a case where the reception means receives a request to stop power transmission from the power receiving device, the detection means performs, in a period of stop of a power transmission, a process of detecting an object using a power transmission coil which was used for the power transmission.