Wireless Power Transfer Coil Control for Foreign Object Heating
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Solution Overview
Problem
Existing wireless power transfer systems face challenges in safely and efficiently transferring power due to the risk of unintentional power transfer to foreign objects, leading to potential overheating and unsafe operation.
Innovation Solution
A power transmitter system that measures a loading parameter indicative of the transmitter coil's loading during inactive power transfer intervals, determines a maximum electromagnetic signal level based on this parameter, and constrains the drive signal to prevent excessive electromagnetic field strength during active power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless power transfer is implemented to eliminate wired connections, then ease of operation is improved, but risk of unintentional power transfer to foreign objects increases causing safety issues
Solution Approach 1:
The system performs foreign object detection by measuring the loading parameter during an inactive time interval before power transfer begins. This preliminary action identifies potential foreign objects in advance, allowing the system to constrain or prevent power transfer to avoid heating and safety hazards while maintaining the convenience of wireless power transfer.
Solution Approach 2:
The system continuously monitors the loading parameter of the transmitter coil and uses this feedback to determine whether to constrain the electromagnetic signal level. The feedback mechanism allows real-time adjustment of power transfer based on detected foreign objects, balancing ease of operation with safety by dynamically controlling power delivery.
2Object-affected harmful factors
If foreign object detection is performed by reducing transmit power, then safety is improved, but power transfer efficiency decreases
Solution Approach 1:
The system performs foreign object detection during an inactive time interval before power transfer begins, rather than continuously during active transfer. This timing strategy allows complete power transfer without constraint when no foreign objects are present, maximizing efficiency while still ensuring safety through preliminary detection.
Solution Approach 2:
The system applies power constraint only partially - specifically when foreign objects are detected through loading parameter measurement. When no foreign objects are present, full power transfer efficiency is maintained. The constraint is excessive only when necessary for safety, not continuously applied.
3Object-affected harmful factors
If maximum electromagnetic signal level is constrained to prevent foreign object heating, then safety is improved, but power transfer capability is reduced
Solution Approach 1:
The system dynamically adjusts the electromagnetic signal level based on real-time loading parameter measurements. The maximum signal level constraint is not fixed but adapts according to detected foreign objects and their characteristics. This dynamic control maintains safety by constraining power only when necessary while preserving full power transfer capability when the transfer path is clear.
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 safer and more flexible power transfer operations, enabling power transfer even when foreign objects are present while preventing unacceptable heating and ensuring safe operation.
Implementation Method 1
a power transmitter for wirelessly providing power to a power receiver via an electromagnetic signal... an output resonance circuit comprising a transmitter coil and at least one capacitor; a driver arranged to generate a drive signal for the output resonance circuit to generate the electromagnetic signal
Implementation Method 2
an output resonance circuit comprising a transmitter coil and at least one capacitor
Data Source
AI summary
A power transmitter (101) providing power to a power receiver (105) via an electromagnetic signal generated by an output resonance circuit comprising a transmitter coil (103) and at least one capacitor (303). A measurer (307) measures a loading parameter which is indicative of a loading of the transmitter coil (103) during a time interval where power transfer is inactive. A determiner (309) determines a maximum electromagnetic signal level for the electromagnetic signal during power transfer in response to the loading parameter. A driver (301) generates a drive signal for the output resonance circuit (103) to generate the electromagnetic signal. The driver (301) is arranged to constrain the drive signal such that the electromagnetic field signal does not exceed the maximum electromagnetic signal level during power transfer.