Slotted foreign object detection during wireless power transfer

Patent metadata

Field	Value
Publication number	US-12463470-B2
Application number	US-202519195504-A
Country	US
Kind code	B2
Filing date	Apr 30, 2025
Priority date	Feb 10, 2021
Publication date	Nov 4, 2025
Grant date	Nov 4, 2025

Abstract

A wireless power transmitter is configured to (i) detect a presence of a wireless power receiver that is couplable with the wireless power transmitter, (ii) after detecting the presence of the wireless power receiver, initiate wireless power transfer with the wireless power receiver, (iii) detect that a given amount of time has elapsed since a prior reference point, (iv) in response to detecting that the given amount of time has elapsed since the prior reference point, (a) pause the wireless power transfer with the wireless power receiver for a temporary period of time and (b) after the wireless power transfer is paused, perform a foreign object detection (FOD) process during the temporary period of time, and (v) after the FOD process is completed, resume the wireless power transfer with the wireless power receiver.

First claim

The invention claimed is:

1 . A wireless power transmitter comprising:
an inverter that is operable to (i) receive, as input, a direct current (DC) voltage signal having a voltage level and a drive signal having an operating frequency and (ii) produce an alternating current (AC) signal based on the DC voltage signal and the drive signal that are provided as input to the inverter; a tuning circuit that is operable to (i) receive the AC signal that is produced by the inverter and (ii) tune the AC signal; a transmission antenna that is operable to emit an alternating electromagnetic field in accordance with the AC signal that is produced by the inverter and tuned by the tuning circuit; and at least one processor; at least one non-transitory machine-readable medium; and executable code stored on the at least one non-transitory machine-readable medium that, when executed by the at least one processor, causes the wireless power transmitter to:
detect a presence of a wireless power receiver that is couplable with the wireless power transmitter;
after detecting the presence of the wireless power receiver, begin engaging in a period of wireless power transfer with the wireless power receiver during which the wireless power transmitter emits, via the transmission antenna, an alternating electromagnetic field that delivers a wireless power signal to the wireless power receiver;
while engaging in the period of wireless power transfer with the wireless power receiver:
determine whether a foreign object has been inserted into the alternating electromagnetic field that delivers the wireless power signal to the wireless power receiver by:
detecting that a given amount of time has elapsed since a prior reference point during the period of wireless power transfer with the wireless power receiver; and
in response to detecting that the given amount of time has elapsed since the prior reference point, (i) temporarily stopping emission of the alternating electromagnetic field that delivers the wireless power signal to the wireless power receiver for a temporary interval of time during the period of wireless power transfer with the wireless power receiver and (ii) after the wireless power transmitter has temporarily stopped emission of the alternating electromagnetic field that delivers the wireless power signal to the wireless power receiver, performing a foreign object detection (FOD) process during the temporary interval of time; and

after the FOD process is completed and the temporary interval of time has ended, resume emission of the alternating electromagnetic field that delivers the wireless power signal to the wireless power receiver during the period of wireless power transfer with the wireless power receiver.

2 . The wireless power transmitter of claim 1 , further comprising executable code stored on the at least one non-transitory machine-readable medium that, when executed by the at least one processor, causes the wireless power transmitter to:
while performing the FOD process, determine that a foreign object is present; and based on determining that the foreign object is present, modify the wireless power transmitter's operation during the resumed emission of the alternating electromagnetic field that delivers the wireless power signal to the wireless power receiver during the period of wireless power transfer with the wireless power receiver.

3 . The wireless power transmitter of claim 1 , wherein performing the FOD process comprises:
performing an analysis of a quality factor (Q) of the transmission antenna; and based on the analysis of the quality factor (Q), determining whether any foreign object is present.

4 . The wireless power transmitter of claim 3 , wherein performing the analysis of the quality factor (Q) of the transmission antenna comprises:
comparing a current value of the quality factor (Q) of the transmission antenna to a baseline value of the quality factor (Q) of the transmission antenna.

5 . The wireless power transmitter of claim 3 , wherein performing the FOD process further comprises:
emitting one or more pings of wireless power signals.

6 . The wireless power transmitter of claim 3 , wherein performing the FOD process further comprises:
performing an analysis of an impedance of the transmission antenna.

7 . The wireless power transmitter of claim 1 , further comprising:
a voltage regulator that is operable to (i) receive a supply DC voltage signal from a power supply and (ii) based on the supply DC voltage signal, produce the DC voltage signal that is provided as input to the inverter.

8 . The wireless power transmitter of claim 1 , wherein the operating frequency of the drive signal comprises an operating frequency defined by a Qi standard.

9 . The wireless power transmitter of claim 1 , wherein the executable code that, when executed by the at least one processor, causes the wireless power transmitter to detect the presence of the wireless power receiver that is couplable with the wireless power transmitter comprises executable code that, when executed by the at least one processor, causes the wireless power transmitter to:
detect a presence of an object; and after detecting the presence of the object, determine that the object comprises the wireless power receiver that is couplable with the wireless power transmitter.

10 . The wireless power transmitter of claim 1 , wherein the tuning circuit comprises at least two capacitors.

11 . A method of operating a wireless power transmitter comprising (i) an inverter that is operable to produce an alternating current (AC) signal based on a direct current (DC) voltage signal having a voltage level and a drive signal having an operating frequency that are provided as input to the inverter, (ii) a tuning circuit that is operable to tune the AC signal, and (iii) a transmission antenna that is operable to emit an alternating electromagnetic field in accordance with the AC signal that is produced by the inverter and tuned by the tuning circuit, the method comprising:
detecting a presence of a wireless power receiver that is couplable with the wireless power transmitter; after detecting the presence of the wireless power receiver, beginning to engage in a period of wireless power transfer with the wireless power receiver during which the wireless power transmitter emits, via the transmission antenna, an alternating electromagnetic field that delivers a wireless power signal to the wireless power receiver; while engaging in the period of wireless power transfer with the wireless power receiver:
determining whether a foreign object has been inserted into the alternating electromagnetic field that delivers the wireless power signal to the wireless power receiver by:
detecting that a given amount of time has elapsed since a prior reference point during the period of wireless power transfer with the wireless power receiver; and
in response to detecting that the given amount of time has elapsed since the prior reference point, (i) temporarily stopping emission of the alternating electromagnetic field that delivers the wireless power signal to the wireless power receiver for a temporary interval of time during the period of wireless power transfer with the wireless power receiver and (ii) after the wireless power transmitter has temporarily stopped emission of the alternating electromagnetic field that delivers the wireless power signal to the wireless power receiver, performing a foreign object detection (FOD) process during the temporary interval of time; and

after the FOD process is completed and the temporary interval of time has ended, resuming emission of the alternating electromagnetic fie

Assignees

• Nucurrent Inc

Inventors

• Melone Mark
• Peralta Alberto
• Katz Michael

Classifications

• H02J13/1335

  involving a local wireless network, e.g. Wi-Fi®, ZigBee® or Bluetooth® · CPC title

• H02J50/80

  involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices · CPC title

• H02J50/402

  the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas · CPC title

• H02J50/60 Primary

  responsive to the presence of foreign objects, e.g. detection of living beings · CPC title

• H02J50/40

  using two or more transmitting or receiving devices (H02J50/50 takes precedence) · CPC title