LOAD IMPEDANCE DECISION DEVICE, WIRELESS POWER TRANSMISSION DEVICE, AND WIRELESS POWER TRANSMISSION METHOD

• US 20130069735A1
• Filed: 11/15/2012
• Published: 03/21/2013
• Est. Priority Date: 11/09/2009
• Status: Active Grant

• Current Assignee: Eun Seok Park, Sang Wook Kwon, Young-Tack Hong
• Original Assignee: Sang Wook Kwon, Young-Tack Hong
• Inventors: Park, Eun Seok, Kwon, Sang Wook, Hong, Young-tack
• Granted Patent: US 8,604,644 B2
• Time in Patent Office: Days
• US Class Current: 333/17.3
• CPC Class Codes: G01R 27/02 Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant by measuring phase angle only G01R25/00
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• 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 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance

Abstract

A load impedance decision device, a wireless power transmission device, and a wireless power transmission method are provided. At least one of a distance and an angle between two resonators may be measured. A load impedance may be determined based on at least one of the measured distance and the measured angle. When the distance between the two resonators changes, a high power transfer efficiency may be maintained without using a separate matching circuit. Where the load impedance is determined, a test power may be transmitted. Depending on a power transfer efficiency of the test power, the load impedance may be controlled and power may be wirelessly transmitted from the source resonator to the target resonator.

Claims

1. A load impedance decision device comprising:

a measurement unit to measure at least one of a distance and an angle between a source resonator and a target resonator; and

a decision unit to determine the load impedance based on at least one of the measured distance and the measured angle.

2. The load impedance decision device of claim 1, wherein the decision unit determines the load impedance based on both the measured distance and the measured angle.

3. The load impedance decision device of claim 1, wherein the load impedance decision unit is included in the source resonator, and the measured angle corresponds to an angle with which the source resonator is tilted with respect to the target resonator.

4. A wireless power transmission device comprising:

a load impedance decision unit; and

a change unit to change an impedance of the wireless power transmission device to be conjugated with a load impedance determined by the load impedance decision unit,

wherein the load impedance decision unit comprises a measurement unit to measure at least one of a distance and an angle between the wireless power transmission device and a target resonator, and a decision unit to determine the load impedance based on at least one of the measured distance and the measured angle.

5. The wireless power transmission device of claim 4, further comprising:

a transmitter to transmit, to a terminal, information associated with the load impedance determined by the load impedance decision unit.

6. The wireless power transmission device of claim 4, wherein the change unit changes the impedance of the wireless power transmission device based on at least one of a tunable resistance, an inductor, and a capacitor.

7. The wireless power transmission device of claim 4, further comprising:

a testing unit to transmit a test power using the changed impedance; and

a control unit to control the load impedance decision unit to re-determine the load impedance when a power transfer efficiency of the test power is less than a reference value, and to control the wireless power transmission device to wirelessly transmit a power using the changed impedance when the power transfer efficiency of the test power is greater than or equal to the reference value.

8. The wireless power transmission device of claim 4, wherein the decision unit determines the load impedance based on both the measured distance and the measured angle.

9. The wireless power transmission device of claim 4, wherein the wireless power transmission device includes a source resonator, and the measured angle corresponds to an angle with which the source resonator is tilted with respect to the target resonator.

10. A terminal to wirelessly receive power, comprising:

a load impedance decision unit; and

a change unit to change an impedance of the terminal to match a load impedance determined by the load impedance decision unit,

wherein the load impedance decision unit comprises a measurement unit to measure at least one of a distance and an angle between the terminal and a target resonator, and a decision unit to determine the load impedance based on at least one of the measured distance and the measured angle.

11. The terminal of claim 10, further comprising:

a transmitter to transmit, to a wireless power transmission device, information associated with the load impedance determined by the load impedance decision unit.

12. The terminal of claim 10, wherein the change unit changes the impedance of the terminal based on at least one of a tunable resistance, an inductor, and a capacitor.

13. The terminal of claim 10, further comprising:

a signal transmitter to transmit a test power request signal to a wireless power transmission device when the change unit changes the impedance of the terminal; and

a control unit to control the load impedance decision unit to re-determine the load impedance when a power transfer efficiency of the test power is less than a reference value, and to transmit a signal to the wireless power transmission device to wirelessly transmit power when the power transfer efficiency of the test power is greater than or equal to the reference value.

14. The terminal of claim 10, wherein the decision unit determines the load impedance based on both the measured distance and the measured angle.

15. The terminal of claim 10, wherein the terminal includes a source resonator, and the measured angle corresponds to an angle with which the source resonator is tilted with respect to the target resonator.

16. A method to determine a load impedance, comprising:

measuring at least one of a distance and an angle between a source resonator and a target resonator; and

determining the load impedance based on at least one of the measured distance and the measured angle.

17. The method of claim 16, wherein the load impedance is determined based on both the measured distance and the measured angle.

18. The method of claim 16, wherein the measured angle corresponds to an angle with which the source resonator is tilted with respect to the target resonator.

19. A method to wirelessly transmit a power, comprising:

determining a load impedance; and

changing an impedance to be conjugated with the determined load impedance,

wherein the determining comprises measuring at least one of a distance and an angle between a source resonator and a target resonator, and determining the load impedance based on at least one of the measured distance and the measured angle.