Wireless Power Transfer Foreign Object Detection via Initial Learning
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Solution Overview
Problem
Existing contactless power transfer systems fail to accurately detect foreign objects between the power transfer device and the power reception device, leading to potential overheating of foreign objects due to uncontrolled power transfer during initial value resets, especially after power outages.
Innovation Solution
A power transfer device equipped with a sensor and controller that executes initial learning to determine the presence of foreign objects by comparing detection results before and after learning, and reduces power transfer when initial learning is not properly executed, ensuring safe operation by preventing large power transfers without proper detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foreign object detection is performed by comparing sensor output changes from initial value, then foreign object detection capability is provided, but detection accuracy deteriorates when initial value is measured in presence of foreign object
Solution Approach 1:
The system performs preliminary actions (reducing power transfer) before the main action (accurate foreign object detection) can be safely executed. By detecting abnormal temperature rises or sensor output changes during a preliminary low-power phase, the system prepares to prevent inaccurate detection results that would occur if full power were applied in the presence of foreign objects.
Solution Approach 2:
The system applies partial action by initially reducing power transfer to a lower level before attempting normal power transfer. This partial power application allows the system to detect foreign objects through sensor output changes without the excessive power that would cause temperature rises or detection failures, thereby resolving the contradiction between detection capability and measurement accuracy.
2Productivity
If power transfer is maintained at normal level, then power transfer efficiency is improved, but foreign object temperature increase occurs undetected
Solution Approach 1:
The system continuously monitors sensor output during power transfer and uses this feedback to detect foreign objects. When sensor output changes indicate the presence of a foreign object, the system responds by reducing power transfer, thereby preventing foreign object temperature rises while maintaining normal power transfer efficiency under normal conditions.
Solution Approach 2:
The system prepares compensatory measures in advance by reducing power transfer when sensor output changes indicate potential foreign object presence. This beforehand cushioning prevents the harmful effect of foreign object temperature rises by detecting and responding to foreign objects before they can be heated by sustained high-power transfer.
3Loss of time
If initial learning is executed automatically, then system initialization speed is improved, but detection reliability deteriorates when foreign object is present during learning
Solution Approach 1:
The system performs preliminary checks during the initial learning phase by monitoring sensor output changes. When changes indicate foreign object presence, the system aborts the automatic initial learning process and transitions to manual initialization, thereby preventing unreliable detection results while still maintaining relatively fast initialization when no foreign objects are present.
Solution Approach 2:
The system dynamically adjusts the initialization process based on real-time sensor feedback. The initial learning mode can automatically transition to manual initialization mode when foreign objects are detected during learning, making the system flexible and adaptive to different conditions while maintaining both speed and reliability.
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 solution effectively suppresses large power transfers to the power reception device even in the presence of foreign objects, preventing overheating and ensuring user safety by allowing controlled initial learning only when confirmed that no foreign objects are present.
Implementation Method 1
a sensor that detects a foreign object present between the power transfer part and the power reception part
Implementation Method 2
a power transfer part that contactlessly transfers power to a power reception part of a power reception device
Implementation Method 3
a magnetic field that is generated along with the power transfer may affect the foreign object and, for example, increase the temperature of the foreign object
Data Source
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AI summary
A power transfer device (100) includes a power transfer part configured to contactlessly transfer power to a power reception part of a power reception device, a sensor configured to detect a foreign object (500) that is present between the power transfer part and the power reception part, and a controller (170) configured to control the power transfer part and the sensor. The controller (170) is configured to execute initial learning that learns an initial state of a detection result of the sensor before initiation of foreign object detection using the sensor. The controller (170) is configured to determine presence of the foreign object (500) by using a difference between the initial state and the detection result of the sensor after execution of the initial learning. The controller (170) is configured to control the power transfer part to reduce power to be transferred to the power reception part when the initial learning is not normally executed.