Wireless Power Coil Q-Factor Checks During Transmission Pauses
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Solution Overview
Problem
Existing wireless power transmission systems lack an effective method for accurately detecting foreign objects using the Q factor measurement, particularly when power transmission is ongoing, leading to inefficiencies and potential damage from foreign objects.
Innovation Solution
A method for foreign object detection using a Q factor measurement based on the transmission power waveform when power transmission is stopped, allowing for precise determination of the presence of foreign objects by comparing measured Q factors with reference values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Q factor measurement is performed during power transmission, then foreign object detection can be conducted in real-time, but switching noise increases and measurement accuracy deteriorates
Solution Approach 1:
The system performs Q factor measurement periodically by temporarily stopping power transmission at specific intervals. This allows accurate measurement during the stop period while maintaining power transmission during normal operation, thus achieving both measurement accuracy and real-time monitoring without continuous noise generation
Solution Approach 2:
The system performs Q factor measurement in advance during the power transmission stop period before resuming power transmission. This preliminary measurement ensures foreign object detection is completed before the next transmission cycle begins, preventing noise interference during critical measurement phases
2Measurement precision
If power transmission is stopped for Q factor measurement, then measurement accuracy improves, but power transmission efficiency decreases
Solution Approach 1:
The system implements periodic Q factor measurements at predetermined intervals during power transmission. By limiting measurements to specific time windows rather than continuous monitoring, the system maintains high measurement accuracy while minimizing interruptions to power transmission and preserving overall transmission efficiency
Solution Approach 2:
The system performs Q factor measurement for a limited duration during power transmission stops rather than requiring complete transmission cessation. This partial action approach achieves sufficient measurement accuracy for foreign object detection while reducing the impact on power transmission efficiency
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 and timely detection of foreign objects without increasing switching noise, ensuring safe and efficient power transmission by utilizing a Q factor measurement in the time domain.
Implementation Method 1
a power transmitting unit configured to wirelessly transmit power to a power receiving apparatus via a power transmission coil
Implementation Method 2
measuring a Q factor from a time-rate change of a voltage in the power transmission coil
Data Source
AI summary
A power transmission apparatus 100 wirelessly transmits power to a power receiving device 102 via a power transmission coil 304, measures a Q factor of the power transmission coil 304 in the time domain, and determines presence or absence of an object (foreign object) different from the power receiving apparatus 102 based on the Q factor measured in the time domain and a reference value of the Q factor which is based on information obtained from the power receiving apparatus 102.