Wireless Power Receiver Foreign Object Detection
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Solution Overview
Problem
Existing wireless power systems face challenges in accurately detecting foreign objects between the transmitter and receiver, which can disrupt power transfer and pose safety hazards, especially in higher-power systems where traditional methods are difficult to implement effectively.
Innovation Solution
A power receiver unit controller is introduced that generates a measurement request, enables a modulator during a predetermined time window, and processes resonant circuit signals to determine the presence of foreign objects, allowing for foreign object detection without interrupting power delivery to the load and eliminating blind spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wireless power transmitter shuts down to detect foreign objects, then foreign object detection capability is improved, but power delivery continuity deteriorates
Solution Approach 1:
The patent inverts the traditional foreign object detection approach by moving the detection function from the transmitter side to the receiver side. The receiver performs self-detection of foreign objects in its vicinity without requiring transmitter shutdown, thereby maintaining continuous power delivery while achieving detection capability. This is accomplished through the receiver analyzing reflected or scattered electromagnetic signals from the foreign objects.
Solution Approach 2:
The receiver continuously monitors the electromagnetic environment and performs foreign object detection in advance before foreign objects can cause harmful effects. By maintaining constant detection capability without interrupting power transfer, the system proactively identifies foreign objects and can take preventive measures, rather than reacting after shutdown is required.
2Device complexity
If traditional foreign object detection methods are used in higher-power systems, then system simplicity is maintained, but detection accuracy deteriorates
Solution Approach 1:
The patent introduces an intermediary detection mechanism where the receiver uses the electromagnetic signals already present in the power transfer path to detect foreign objects. Instead of requiring complex dedicated detection hardware, the system utilizes the existing electromagnetic field as a mediator for detection, achieving accurate foreign object detection in high-power systems without proportionally increasing system complexity.
3Measurement precision
If the receiver enables modulator during measurement window, then foreign object detection precision is improved, but power transfer efficiency deteriorates
Solution Approach 1:
The receiver enables the modulator periodically during specific measurement windows to perform foreign object detection. By confining modulator activation to brief periodic intervals rather than continuous operation, the system achieves necessary detection precision while minimizing energy loss and maintaining overall power transfer efficiency. The periodic measurement windows are strategically timed to cause minimal disruption to continuous power delivery.
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 solution enables precise foreign object detection on the receiver side, reducing power interruption risks and eliminating blind spots, thereby enhancing the safety and efficiency of wireless power transfer systems.
Implementation Method 1
receive a measurement signal corresponding to a resonant circuit signal in a resonant circuit of the wireless power receiver; process the measurement signal and determine whether a foreign object is present between the wireless power receiver and the wireless power transmitter from the processed measurement signal
Data Source
AI summary
A system and method to detect the presence of conductive foreign objects for a multi-coil wireless power system is described. A wireless power receiver resonant circuit quality information may be obtained without any costly hardware or termination of power delivery to the power receiver load. The power receiver free-running coil current or voltage may be measured during a very short time window. In this time window, the measurement may be unaffected by transmitter and receiver load due to the transmitter coil disconnection and because the wireless power receiver has sufficient DC-bus capacitance.