Robust foreign objects detection
First Claim
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1. A foreign object detection method for a wireless power transmitter having a matching network and transmit coil, the method comprising:
- (A) energizing the matching network and transmit coil and exciting resonance between the matching network and transmit coil;
(B) allowing the resonance to decay;
(C) measuring a temporal characteristic of the decay; and
(D) analyzing the temporal characteristic to determine whether a foreign object is coupled to an electromagnetic field generated by the transmit coil,wherein (A) comprises switching an inverter of the wireless power transmitter, andwherein (A) transfers sufficient energy to a wireless power receiver to charge a rectifier filter capacitor of the wireless power receiver to a level sufficient to reverse bias rectifier diodes of the wireless power receiver prior to (B).
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Abstract
An apparatus and method for performing foreign object detection for a wireless power transmitter. A matching network and transmit coil are energized, and a resonance is excited. The resonance is allowed to decay. A temporal characteristic of the decay is measured. The temporal characteristic is analyzed to determine whether a foreign object is coupled to an electromagnetic field generated by the transmit coil.
22 Citations
20 Claims
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1. A foreign object detection method for a wireless power transmitter having a matching network and transmit coil, the method comprising:
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(A) energizing the matching network and transmit coil and exciting resonance between the matching network and transmit coil; (B) allowing the resonance to decay; (C) measuring a temporal characteristic of the decay; and (D) analyzing the temporal characteristic to determine whether a foreign object is coupled to an electromagnetic field generated by the transmit coil, wherein (A) comprises switching an inverter of the wireless power transmitter, and wherein (A) transfers sufficient energy to a wireless power receiver to charge a rectifier filter capacitor of the wireless power receiver to a level sufficient to reverse bias rectifier diodes of the wireless power receiver prior to (B). - View Dependent Claims (2, 3, 4, 5, 6)
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7. A foreign object detection method for a wireless power transmitter having a matching network and transmit coil, the method comprising:
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(A) energizing the matching network and transmit coil and exciting resonance between the matching network and transmit coil; (B) allowing the resonance to decay; (C) measuring a temporal characteristic of the decay; and (D) analyzing the temporal characteristic to determine whether a foreign object is coupled to an electromagnetic field generated by the transmit coil, wherein (A) comprises switching an inverter of the wireless power transmitter, and wherein (A) comprises switching the inverter for a first period of time and a second period of time after the first period of time, wherein the inverter transfers a lower energy level in the second period of time than in the first period of time. - View Dependent Claims (8, 9, 10, 11)
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12. A foreign object detection method for a wireless power transmitter having a matching network and transmit coil, the method comprising:
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(A) energizing the matching network and transmit coil and exciting resonance between the matching network and transmit coil; (B) allowing the resonance to decay; (C) measuring a temporal characteristic of the decay; and (D) analyzing the temporal characteristic to determine whether a foreign object is coupled to an electromagnetic field generated by the transmit coil, wherein (D) comprises determining a quality factor, and wherein (D) comprises comparing the quality factor to an acceptable quality factor for wireless power transmission. - View Dependent Claims (13)
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14. An apparatus for driving a wireless power transmitter and performing foreign object detection, the apparatus comprising:
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a drive circuit configured to energize a matching network and transmit coil of the wireless power transmitter, excite resonance between the matching network and transmit coil, and allow the resonance to decay; and a controller configured to control the drive circuit, measure a temporal characteristic of the decay and analyze the temporal characteristic to determine whether a foreign object is coupled to an electromagnetic field generated by the transmit coil, wherein the drive circuit comprises an inverter configured to energize and excite the resonance by switching in response to a control signal produced using the controller, and wherein the inverter is switched for a first period of time and a second period of time after the first period of time to energize and excite resonance of the matching network and transmit coil, wherein the inverter transfers a higher energy level in the first period of time than in the second period of time. - View Dependent Claims (15, 16, 17, 18)
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19. An apparatus for driving a wireless power transmitter and performing foreign object detection, the apparatus comprising:
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a drive circuit configured to energize a matching network and transmit coil of the wireless power transmitter, excite resonance between the matching network and transmit coil, and allow the resonance to decay; and a controller configured to control the drive circuit, measure a temporal characteristic of the decay and analyze the temporal characteristic to determine whether a foreign object is coupled to an electromagnetic field generated by the transmit coil, wherein the controller is configured to determine a quality factor, and wherein the controller is configured to compare the quality factor to an acceptable quality factor for wireless power transmission. - View Dependent Claims (20)
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Specification