Wireless Inductive Power Transfer Foreign Object Detection
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Solution Overview
Problem
Current wireless power transfer systems, particularly those adhering to the Qi standard, face challenges in accurately detecting foreign objects at higher power levels, leading to potential overheating and unsafe conditions, as existing methods require calibration and user involvement, which are inconvenient and may result in false detections or missed detections.
Innovation Solution
A wireless power transfer system that operates in both test and power transfer modes, with a foreign object detection performed in the test mode to ensure accuracy, and parasitic power loss detection in the power transfer mode, using constrained loading in the test mode to enhance detection reliability and adapt parasitic power loss detection based on initial operating parameters to minimize false positives and negatives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foreign object detection is performed using existing methods in wireless power transfer systems, then detection capability is provided, but the system requires calibration and user involvement which reduces ease of operation and may result in false detections or missed detections reducing reliability
Solution Approach 1:
The system performs self-calibration by automatically determining calibration values through test power transfer operations without requiring user involvement. The power transmitter and power receiver autonomously execute the calibration process, storing the determined calibration values for subsequent foreign object detection operations, thereby eliminating the need for manual user calibration while maintaining detection accuracy
Solution Approach 2:
The system performs calibration operations in advance before normal power transfer operations. By executing test power transfer and determining calibration values during an initial phase, the system prepares the necessary detection parameters beforehand, ensuring accurate foreign object detection during subsequent operations without requiring user intervention at the time of detection
2Power
If wireless power transfer operates at higher power levels, then power transfer capability is improved, but foreign object detection accuracy deteriorates leading to potential overheating and unsafe conditions
Solution Approach 1:
The system dynamically adjusts detection parameters based on the current power transfer level. By determining calibration values that correspond to specific power levels and using these calibrated values to establish detection thresholds, the system maintains accurate foreign object detection across varying power levels, preventing both false detections and missed detections at high power operations
3Measurement precision
If calibration is performed to improve foreign object detection accuracy, then detection precision is improved, but the process requires user involvement and time which reduces productivity
Solution Approach 1:
The system autonomously performs calibration without requiring user involvement. The power transmitter and power receiver automatically execute test power transfer operations, determine calibration values, and store them for future use, eliminating the time users would need to spend on calibration while achieving accurate foreign object detection
Solution Approach 2:
The calibration values determined during test operations are stored and reused for subsequent foreign object detection operations. This allows the system to maintain high detection precision without repeating the calibration process, thereby eliminating ongoing time losses that would otherwise be required for repeated calibration procedures
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 provides a more reliable and user-friendly foreign object detection, reducing the risk of overheating and improving the accuracy of power transfer operations, allowing for safer and more efficient wireless charging without the need for extensive user calibration or involvement.
Implementation Method 1
a transmit power inductor (103) for generating a wireless inductive power signal
Data Source
AI summary
A wireless power transfer system includes a power transmitter (101) providing power to a power receiver (105) via an inductive power signal. The power transmitter (101) and receiver (105) can operate in different modes including a test mode and a power transfer mode. Operating parameters of the power receiver (105) are constrained in the test mode relative (and specifically the loading). A foreign object detector (209) generates a foreign object detection estimate from a comparison of a measured load to an expected load of the inductive power signal when the power receiver is operating in the test mode. A controller (211) enters the power transmitter (101) and receiver (103) into the power transfer mode when the foreign object detection estimate is indicative of no detection of a foreign object. In the power transfer mode, a parasitic power loss detector (207) generates a parasitic power loss detection for the power transfer if a parasitic power loss estimate is outside a range.