Wireless Power Coil Q-Factor Detection for Foreign Objects
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Solution Overview
Problem
Existing wireless power transfer systems face challenges in accurately detecting foreign objects that can affect power transmission efficiency and cause heat generation, as current methods may result in detection errors or fail to identify objects within the transmission range.
Innovation Solution
A power transmission apparatus and reception apparatus that utilize Q factor measurements in both frequency and time domains, combined with power loss analysis, to enhance foreign object detection accuracy by comparing measured Q factors with reference values and power loss thresholds, enabling precise control of power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Q factor measurement is performed in a wireless power transfer system, then foreign object detection capability is improved, but measurement precision deteriorates due to detection errors
Solution Approach 1:
The patent applies preliminary action by measuring the Q factor during the negotiation phase before power transmission begins. This allows the system to establish baseline characteristics and detect foreign objects before actual power transfer, preventing detection errors that could occur during active transmission when power interference is present.
Solution Approach 2:
The patent uses communication packets as an intermediary to transmit Q factor measurement results from the power reception apparatus to the power transmission apparatus. This indirect measurement approach allows foreign object detection without requiring direct interference with the power transmission process, thereby maintaining measurement precision while improving detection reliability.
2Reliability
If foreign object detection is performed during power transmission, then safety is improved, but power transmission efficiency deteriorates due to interruptions
Solution Approach 1:
The system performs foreign object detection during the negotiation phase before power transmission starts. By completing safety checks in advance, the system avoids interruptions during actual power transfer, thereby maintaining high transmission efficiency while ensuring safety through prior detection.
Solution Approach 2:
The power reception apparatus measures the Q factor and provides feedback to the power transmission apparatus through communication packets. This feedback mechanism enables continuous monitoring without interrupting power transmission, as the measurement and communication occur in parallel with the power transfer process.
3Measurement precision
If multiple detection methods are used to improve accuracy, then detection precision is improved, but device complexity increases
Solution Approach 1:
The patent combines Q factor measurement with the existing negotiation phase communication protocol. By merging the detection function into the already-established communication framework, the system achieves improved detection accuracy without significantly increasing overall system complexity, as it reuses existing communication infrastructure.
Solution Approach 2:
The communication unit serves multiple functions: it enables power negotiation, transmits control signals, and conveys Q factor measurement results for foreign object detection. This multi-functionality allows the system to achieve enhanced detection capabilities without adding dedicated separate components, thereby avoiding excessive complexity increase.
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
The proposed method improves foreign object detection accuracy, reducing the likelihood of detection errors and ensuring safe and efficient power transfer by accurately identifying and responding to the presence of foreign objects.
Implementation Method 1
a power transmission unit configured to wirelessly transmit power to a power reception apparatus via a power transmission coil
Implementation Method 2
a measurement unit configured to measure a Q factor of the power transmission coil in a phase for performing power transmission from the power transmission apparatus to the power reception apparatus
Data Source
AI summary
A power transmission apparatus that can wirelessly transmit power to a power reception apparatus via a power transmission coil and communicate with the power reception apparatus determines presence/absence of an object different from the power reception apparatus based on a Q factor of the power transmission coil measured in a phase for performing power transmission. The power transmission apparatus controls whether to execute the determination of presence/absence of the object different from the power reception apparatus based on measurement of the Q factor of the power transmission coil, based on information received from the power reception apparatus through communication that represents whether the power reception apparatus can execute predetermined processing associated with the determination of presence/absence of the object different from the power reception apparatus based on the measurement of the Q factor of the power transmission coil.