Methods and systems for detecting foreign objects in a wireless charging system
First Claim
Patent Images
1. A wireless power charging system for charging a separate device having a power receiver coil, the wireless power charging system comprising:
- at least one power transmitter coil configured to;
transmit, during a first time period, electromagnetic energy to pre-charge the power charging system through the power receiver coil in the separate device,transmit, based on an indication of an absence of a foreign object disposed between the power transmitter coil and the power receiver coil, power by inductive coupling to the power receiver coil in the separate device, the power transmitter coil characterized by a transmitter coil dimension that is a lateral dimension of the power transmitter coil; and
a foreign object sensor including at least one foreign object detection (FOD) coil positioned at the center of the power transmitter coil, the FOD coil characterized by a FOD coil dimension that is the lateral dimension of the FOD coil and that is smaller than the transmitter coil dimension, the foreign object sensor configured to;
determine an initial amplitude level of an electromagnetic foreign object detection signal during a calibration operation when the foreign object is not disposed between the power transmitter coil and the power receiver coil,generate, during a second time period subsequent to the first time period, the electromagnetic foreign object detection signal having a current amplitude level,determine whether the current amplitude level of the electromagnetic foreign object detection signal is lower than the initial amplitude level, andgenerate an indication of the presence of the foreign object disposed between the power transmitter coil and the power receiver coil responsive to a determination that current amplitude level is lower than the initial amplitude level, and otherwise generate the indication of the absence of the foreign object disposed between the power transmitter coil and the power receiver coil.
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Abstract
Methods and systems are described for using detection coils to detect metallic or conductive foreign objects that can interfere with the wireless transfer of power from a power transmitter to a power receiver. In particular, the detection coils are targeted to foreign objects that are smaller than a power transmitter coil in the power transmitter.
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Citations
20 Claims
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1. A wireless power charging system for charging a separate device having a power receiver coil, the wireless power charging system comprising:
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at least one power transmitter coil configured to; transmit, during a first time period, electromagnetic energy to pre-charge the power charging system through the power receiver coil in the separate device, transmit, based on an indication of an absence of a foreign object disposed between the power transmitter coil and the power receiver coil, power by inductive coupling to the power receiver coil in the separate device, the power transmitter coil characterized by a transmitter coil dimension that is a lateral dimension of the power transmitter coil; and a foreign object sensor including at least one foreign object detection (FOD) coil positioned at the center of the power transmitter coil, the FOD coil characterized by a FOD coil dimension that is the lateral dimension of the FOD coil and that is smaller than the transmitter coil dimension, the foreign object sensor configured to; determine an initial amplitude level of an electromagnetic foreign object detection signal during a calibration operation when the foreign object is not disposed between the power transmitter coil and the power receiver coil, generate, during a second time period subsequent to the first time period, the electromagnetic foreign object detection signal having a current amplitude level, determine whether the current amplitude level of the electromagnetic foreign object detection signal is lower than the initial amplitude level, and generate an indication of the presence of the foreign object disposed between the power transmitter coil and the power receiver coil responsive to a determination that current amplitude level is lower than the initial amplitude level, and otherwise generate the indication of the absence of the foreign object disposed between the power transmitter coil and the power receiver coil. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A wireless power charging system for charging a separate device having a power receiver coil, the wireless power charging system comprising:
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at least one power transmitter coil configured to; transmit, during a first time period, electromagnetic energy to pre-charge the power charging system through the power receiver coil in the separate device, transmit, based on an indication of an absence of a foreign object disposed between the power transmitter coil and the power receiver coil, power by inductive coupling to the power receiver coil in the separate device, the power transmitter coil characterized by a transmitter coil dimension that is a lateral dimension of the power transmitter coil; and a foreign object sensor including at least one foreign object detection (FOD) coil positioned at the center of the power transmitter coil, the FOD coil characterized by a FOD coil dimension that is the lateral dimension of the FOD coil and that is smaller than the transmitter coil dimension, the foreign object sensor configured to; determine an initial oscillation duration of an electromagnetic foreign object detection signal during a calibration operation when a foreign object is not disposed between the power transmitter coil and the power receiver coil, generate, during a second time period subsequent to the first time period, the electromagnetic foreign object detection signal having a current oscillation duration, determine whether the current oscillation duration of the electromagnetic foreign object detection signal is shorter than the initial oscillation duration, and generate an indication of the presence of the foreign object disposed between the power transmitter coil and the power receiver coil responsive to a determination that current oscillation duration is shorter than the initial oscillation duration, and otherwise generate the indication of the absence of the foreign object disposed between the power transmitter coil and the power receiver coil.
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Specification