APPARATUS AND METHOD FOR PERFORMING FOREIGN OBJECT DETECTION IN WIRELESS POWER TRANSFER SYSTEM

• US 20190326786A1
• Filed: 04/04/2019
• Published: 10/24/2019
• 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
• Granted Patent: US 11,050,300 B2
• Time in Patent Office: Days
• 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 receiving wireless power from a wireless power transmitter by a wireless power receiver based on foreign object detection in a wireless power transfer system, the 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 state packet which indicates a reference Q factor (Q_ref) of the wireless power receiver to the wireless power transmitter; and

receiving wireless power through magnetic coupling with the wireless power transmitter based on a foreign object detection result of the wireless power transmitter using the reference Q factor,

wherein the reference Q factor is a Q factor of a reference wireless power transmitter with respect to the wireless power receiver in the absence of a nearby foreign object,

wherein 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.

2. The method of claim 1, wherein if a first Q factor is denoted as a threshold Q factor (Q_ref,OX) by which the representative foreign object is detected where the 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 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.

4. The method of claim 1, wherein the minimum reference Q factor is defined as a value compensating the threshold Q factor for a Q factor measurement error.

5. The method of claim 4, 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.

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

7. The method of claim 6, wherein the minimum reference Q factor ranges from 24.7 to 25.

8. The method of claim 2, wherein the representative foreign object is a representative foreign object which maximizes the threshold Q factor among various types of representative foreign objects.

9. A method for transferring wireless power to a wireless power receiver by a wireless power transmitter based on foreign object detection in a wireless power transfer system, the method comprising:

transmitting a digital ping to the wireless power receiver;

receiving an identification and configuration packets from the wireless power receiver;

receiving a foreign object detection state packet which indicates a reference Q factor (Q_ref) of the wireless power receiver from the wireless power receiver;

performing foreign object detection by using the reference Q factor; and

transferring wireless power through magnetic coupling to the wireless power receiver based on the foreign object detection result.

wherein the reference Q factor is a Q factor of a reference wireless power transmitter with respect to the wireless power receiver in the absence of a nearby foreign object,

wherein 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.

10. The method of claim 9, 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.

11. The method of claim 9, 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.

12. The method of claim 11, wherein the minimum reference Q factor is defined as a value compensating the threshold Q factor for a Q factor measurement error.

13. The method of claim 12, 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.

14. The method of claim 13, wherein the threshold Q factor is 22.2.

15. 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.

16. The method of claim 15, 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.

17. The method of claim 15, 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.

18. The method of claim 16, wherein the minimum reference Q factor is defined as a value compensating the threshold Q factor for a Q factor measurement error.

19. The method of claim 18, 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.

20. The method of claim 19, wherein the threshold Q factor is 22.2.