FOREIGN SUBSTANCE DETECTION METHOD FOR WIRELESS CHARGING AND APPARATUS THEREFOR

• US 20190312468A1
• Filed: 12/08/2017
• Published: 10/10/2019
• Est. Priority Date: 12/08/2016
• Status: Active Grant

• Current Assignee: LG Innotek Company Limited (LG Corporation)
• Original Assignee: LG Innotek Company Limited (LG Corporation)
• Inventors: KWON, YONG IL, PARK, JAE HEE
• Granted Patent: US 11,056,924 B2
• Time in Patent Office: Days
• CPC Class Codes: H02J 50/12 of the resonant type
• 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 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

The present invention relates to a foreign substance detection method, and an apparatus and a system therefor. A foreign substance detection method in a wireless power transmitter, according to an embodiment of the present invention, may comprise the steps of: if an object placed in a charging area is detected, searching for a current peak frequency with a maximum quality factor value in an available frequency band; receiving, from a wireless power receiver, a foreign substance detection state packet including a reference peak frequency; determining a foreign substance detection reference frequency on the basis of the reference peak frequency; and determining whether or not a foreign substance is present by comparing the current peak frequency with the foreign substance detection reference frequency. Therefore, the present invention has an advantage of being capable of detecting a foreign substance more effectively and accurately.

Claims

1. A foreign object detection method of a wireless power transmitter, the foreign object detection method comprising:

detecting an object placed in a charging area to measure a peak frequency having a maximum quality factor value;

receiving a foreign object detection status packet including a reference peak frequency from a wireless power receiver;

determining a frequency for detecting a foreign object based on the reference peak frequency; and

comparing the peak frequency with the determined frequency to determine whether a foreign object is present.

2. The foreign object detection method according to claim 1, wherein the determining of the frequency for detecting the foreign object includes determining the frequency for detecting the foreign object by a sum of the reference peak frequency and a tolerance.

3. The foreign object detection method according to claim 1, wherein, when the peak frequency is greater than the frequency for detecting the foreign object, a determination is made that the foreign object is present.

4. The foreign object detection method according to claim 1, wherein the wireless power transmitter measures the peak frequency before the wireless power receiver receives a ping signal.

5. The foreign object detection method according to claim 1, wherein the reference peak frequency has a maximum quality factor value within an available frequency band in a state in which only the wireless power receiver is placed in the charging area.

6. The foreign object detection method according to claim 1, wherein the foreign object detection status packet further includes mode information, and the wireless power transmitter identifies the reference peak frequency included in the foreign object detection status packet based on the mode information.

7. A foreign object detection apparatus for detecting a foreign object placed in a charging area, the foreign object detection apparatus comprising:

a coil unit including an inductor and a resonant capacitor and configured to convert current into flux of magnetic force;

an inverter configured to receive and convert direct current (DC) power into alternating current (AC) power and to transmit the AC power to the coil unit; and

a controller configured to control a frequency of the AC power output from the inverter and to demodulate a signal using a voltage or current of the coil unit,

wherein the controller is configured to;

detect an object placed in the charging area to measure a peak frequency having a maximum quality factor value,

receive a foreign object detection status packet including a reference peak frequency from a wireless power receiver,

determine a frequency for detecting a foreign object based on the reference peak frequency, and compare the peak frequency with the determined frequency to determine whether a foreign object is present.

8. The foreign object detection apparatus according to claim 7, wherein the controller determines the frequency for detecting the foreign object by a sum of the reference peak frequency and a tolerance.

9. The foreign object detection apparatus according to claim 7, wherein the controller measures the peak frequency before the wireless power receiver receives a ping signal.

10. The foreign object detection apparatus according to claim 7, wherein the reference peak frequency corresponds to a maximum quality factor value within an available frequency band in a state in which only the wireless power receiver is placed in the charging area.