Wireless Power Coil Monitoring for Foreign Object Heat Detection
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Solution Overview
Problem
Foreign objects between the transmitter and receiver coils in wireless power transfer systems cause unnecessary power dissipation, reducing efficiency and posing safety risks due to heat generation.
Innovation Solution
A method involving power loss calibration, Q factor measurement, and coupling factor analysis to detect foreign objects by comparing measured values with predetermined thresholds, and halting power transfer upon relative position changes or excessive power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless power transfer is enabled between transmitter and receiver coils, then power transfer efficiency is improved, but foreign objects may cause unnecessary power dissipation and heat generation
Solution Approach 1:
The patent performs foreign object detection before enabling power transfer by measuring the Q factor of the transmitter coil. This preliminary action identifies foreign objects in advance, preventing them from causing heat generation during power transfer, thus resolving the contradiction between maintaining power transfer efficiency and preventing harmful thermal effects.
Solution Approach 2:
The system continuously monitors the Q factor and coupling factor during operation, comparing measured values against reference thresholds. This feedback mechanism enables real-time detection of foreign objects or position changes, allowing the system to adjust or halt power transfer to prevent excessive power dissipation and heat generation while maintaining efficient operation under normal conditions.
2Reliability
If foreign object detection is performed using Q factor measurement, then foreign objects can be detected, but the system complexity increases
Solution Approach 1:
The system uses the existing transmitter coil and its inherent electrical properties (Q factor) for foreign object detection, rather than requiring separate dedicated detection sensors. The transmitter coil serves dual purposes: power transfer and foreign object detection, reducing overall system complexity while maintaining detection reliability.
Solution Approach 2:
The same transmitter coil infrastructure is utilized for both wireless power transfer and foreign object detection functions. By measuring the Q factor using the existing coil and control circuitry, the system achieves multi-functionality without adding separate detection hardware, thus resolving the contradiction between detection accuracy and system complexity.
3Measurement precision
If power loss calibration is performed to detect foreign objects, then detection accuracy is improved, but the measurement time increases
Solution Approach 1:
The system performs power loss calibration and establishes reference Q factor values before normal power transfer operations begin. This preliminary calibration ensures accurate baseline measurements for detecting foreign objects, improving detection precision while minimizing time loss during actual power transfer by having references pre-established.
Solution Approach 2:
Once calibration is complete, the system continuously monitors Q factor and coupling factor during normal operation without requiring repeated full calibration sequences. This maintains high measurement precision for foreign object detection while minimizing time loss, as the system only performs quick comparative measurements against established references rather than repeated full calibrations.
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
Accurately detects foreign objects, ensuring efficient and safe power transfer by preventing power dissipation and temperature rises, and maintaining system integrity.
Implementation Method 1
The primary side transmitter is configured to generate an alternating current on the primary side coil to form a varying magnetic field, thereby generating a voltage in the secondary side coil
Implementation Method 2
measuring a coupling factor between a transmitter coil and a receiver coil of the wireless power transfer system
Data Source
AI summary
A method includes performing a power loss calibration on a wireless power transfer system, enabling a wireless power transfer on the wireless power transfer system, calculating a power loss of the wireless power transfer system based on the power loss calibration, measuring a coupling factor between a transmitter coil and a receiver coil of the wireless power transfer system, and determining whether to continue the wireless power transfer of the wireless power transfer system based on the calculated power loss and the measured coupling factor.