Wireless charging system with power level calculation circuit for foreign object detection

• US 10,763,706 B2
• Filed: 07/05/2018
• Issued: 09/01/2020
• Est. Priority Date: 12/12/2017
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Chen, Fei, Li, Gang, Zhao, Ping
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Pham, Duc M
• Application Number:
  US16/028,378
• Publication Number:
  US 20190181692A1
• Time in Patent Office: 789 Days
• 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

Abstract

In a wireless charging system, a power-transmitting node (TX) has a transmitter for transmitting power wirelessly to a power-receiving node (RX), and a signal receiver for receiving signals from the RX. During a power-transfer session, the TX accumulates data corresponding to its transmitted power level, detects an end of a received power (RP) packet from the RX, and then identifies a subset of the accumulated data. The TX calculates its transmitted power level using the subset of the accumulated data. The TX extracts a received power level of the RX from the received RP packet and compares its calculated transmitted power level with the RX'"'"'s received power level to determine a presence of a foreign object. Accuracy of FO detection when packets from the RX are not properly received by the TX is improved.

Claims

1. A power-transmitting node (TX) for transmitting power wirelessly to a power-receiving node (RX) in a wireless charging system, the TX comprising:

a processor that (i) accumulates data corresponding to transmitted power level of the TX, (ii) detects an end of a received power (RP) packet received from the RX, (iii) then identifies a subset of the accumulated data, and (iv) calculates the transmitted power level of the TX using the subset of the accumulated data;

a memory that stores the accumulated data;

a power transmitter that transmits power wirelessly to the RX; and

a signal receiver that receives the RP packet from the RX.

2. The TX of claim 1, wherein the processor further extracts a received power level of the RX from the received RP packet and compares the transmitted power level of the TX with the received power level of the RX to detect a presence of a foreign object (FO).

3. The TX of claim 1, wherein the processor identifies the subset of the accumulated data as the data within a timing window that ends a known duration before the end of the RP packet.

4. The TX of claim 1, wherein the processor identifies the subset of the accumulated data as the accumulated data within a timing window that ends a known duration before a detected beginning of the RP packet.

5. The TX of claim 1, wherein the processor continuously accumulates the data corresponding to the transmitted power level of the TX throughout a power-transfer session of the TX.

6. The TX of claim 1, wherein the processor stores the accumulated data in a buffer in the memory.

7. The TX of claim 1, wherein:

the processor extracts a received power level of the RX from the received RP packet and compares the transmitted power level of the TX with the received power level of the RX to detect a presence of a foreign object (FO);

the processor continuously accumulates the data corresponding to the transmitted power level of the TX throughout a power-transfer session of the TX; and

the processor stores the accumulated data in a buffer in the memory.

8. The TX of claim 7, wherein the processor identifies the subset of the accumulated data as the accumulated data within a timing window that ends a known duration prior to the end of the RP packet.

9. The TX of claim 7, wherein the processor identifies the subset of the accumulated data as the accumulated data within a timing window that ends a known duration prior to a detected beginning of the RP packet.

10. A method for a wireless transmitter (TX) transmitting power wirelessly to a receiver (RX) in a wireless charging system, the method comprising:

transmitting the power wirelessly by the TX to the RX;

accumulating data corresponding to a transmitted power level of the TX, by the TX and storing the accumulated data in a memory of the TX;

detecting an end of an RP packet received from the RX;

after detecting the end of the RP packet, identifying a subset of the accumulated data; and

calculating the transmitted power level of the TX based on the subset of the accumulated data.

11. The method of claim 10, further comprising extracting a received power level of the RX from the received RP packet and comparing the transmitted power level of the TX with the received power level of the RX to detect the presence of an FO.

12. The method of claim 10, wherein the subset of the accumulated data is identified as the accumulated data within a timing window that ends a known duration before the end of the RP packet.

13. The method of claim 10, wherein the subset of the accumulated data is identified as the accumulated data within a timing window that ends a known duration before a detected beginning of the RP packet.

14. The method of claim 10, wherein the data corresponding to the transmitted power level of the TX is continuously accumulated throughout a power-transfer session of the TX.

15. The method of claim 10, wherein the accumulated data is stored in a buffer in the memory.

16. The method of claim 10, further comprising extracting a received power level of the RX from the received RP packet and comparing the transmitted power level of the TX with the received power level of the RX to detect presence of an FO, wherein:

the data corresponding to the transmitted power level of the TX is continuously accumulated throughout a power-transfer session of the TX; and

the accumulated data is stored in a buffer in the memory.

17. The method of claim 16, wherein the subset of the accumulated data is identified as the accumulated data within a timing window that ends a known duration before the end of the RP packet.

18. The method of claim 16, wherein the subset of the accumulated data is identified as the accumulated data within a timing window that ends a known duration before a detected beginning of the RP packet.