Apparatus and method for performing foreign object detection in wireless power transfer system

• US 11,050,300 B2
• Filed: 04/04/2019
• Issued: 06/29/2021
• Est. Priority Date: 04/18/2018
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Kim, Kyunghwan, Park, Yongcheol, Lee, Jihyun, Yook, Gyunghwan
• Primary Examiner(s): Skibinski, Tomi
• Application Number:
  US16/375,823
• Publication Number:
  US 20190326786A1
• Time in Patent Office: 817 Days
• Field of Search: 307104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/402 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 Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

Provided are an apparatus and method for performing foreign object detection in a wireless power transfer system. The present specification discloses a method comprising receiving a digital ping from the wireless power transmitter; transmitting an identification and configuration packets to the wireless power transmitter; transmitting a foreign object detection (FOD) state packet which indicates a reference Q factor of the wireless power receiver to the wireless power transmitter; and receiving wireless power through magnetic coupling from the wireless power transmitter based on the foreign object detection result of the wireless power transmitter using the reference Q factor. Irrespective of individual characteristics of a wireless power receiver, accuracy and reliability of detecting a foreign object may be improved.

Claims

1. A method for testing foreign object detection performance of a wireless power receiver in a wireless power transfer system, the method comprising:

measuring a Q factor with respect to a wireless power receiver at a predetermined test position on a reference wireless power transmitter;

comparing the measured Q factor with a reference Q factor provided by the wireless power receiver; and

if the reference Q factor is larger than or equal to the minimum reference Q factor (Q_{ref min}) required for an arbitrary wireless power receiver compatible with the reference wireless power transmitter, and the measured Q factor belongs to an error range of the reference Q factor, determining a foreign object detection performance test of the wireless power receiver as being successful.

2. The method of claim 1, wherein if the first Q factor is denoted as a threshold Q factor (Q_ref,OX) by which the representative foreign object is detected where a first Q factor (Q_RX) of a reference wireless power transmitter with respect to the arbitrary wireless power receiver in the absence of a nearby foreign object is the same as a second Q factor (Q_RX,RFO) of the reference wireless power transmitter with respect to the arbitrary wireless power receiver in the presence of a nearby representative foreign object (RFO), the minimum Q factor value is defined based on the threshold Q factor.

3. The method of claim 2, wherein the minimum reference Q factor is defined as a value compensating the threshold Q factor for a Q factor measurement error.

4. The method of claim 3, wherein the threshold Q factor ranges from 22 to 23, the Q factor measurement error lies within 10% of the threshold Q factor, and the minimum reference Q factor ranges from 24 to 26.

5. The method of claim 4, wherein the threshold Q factor is 22.2.

6. The method of claim 1, wherein, when Δ

Q factor=second Q factor−

first Q factor, the minimum reference Q factor is defined based on the first Q factor which satisfies Δ

Q factor=0;

the first Q factor is a Q factor of a reference wireless power transmitter with respect to the arbitrary wireless power receiver in the absence of a nearby foreign object; and

the second Q factor is a Q factor of the reference wireless power transmitter with respect to the arbitrary wireless power receiver in the presence of a nearby representative foreign object.