Method and apparatus for controlling wireless power transmission

1. A wireless power transmitter, comprising:

a controller configured to determine an output power;

a power converter configured to output the output power;

a resonator configured to wirelessly transmit the output power to a target device; and

a power detector configured to detect a current of the output power,

wherein the controller is further configured to detect a change in the current using the power detector, determine a state of a wireless power transmission based on the detected change in the current, and control an operation for the wireless power transmission to the target device based on the determined state of the wireless power transmission.

2. The wireless power transmitter of claim 1 , wherein the controller is further configured to receive a state of the target device from the target device, and to determine the state of wireless power transmission based on the detected change in the current and the received state of the target device.

3. The wireless power transmitter of claim 1 , wherein, in response to the current being changed within a predetermined period of time, the controller determines that the current remains unchanged.

4. The wireless power transmitter of claim 1 , wherein, in response to the current being changed within a predetermined range, the controller determines that the current remains unchanged.

5. The wireless power transmitter of claim 1 , wherein, in response to the current being changed for more than a predetermined period of time, the controller is configured to request the target device to transmit a state of the target device.

6. The wireless power transmitter of claim 2 , wherein the controller is configured to control the operation of the wireless power transmission by adjusting the output power based on the received state of the target device.

7. The wireless power transmitter of claim 1 , wherein, in response to the current being changed to a current corresponding to a load indicating that the target device has been removed, the controller controls the operation for the wireless power transmission by interrupting an output of the output power.

8. The wireless power transmitter of claim 2 , wherein, in response to the current corresponding to a load that occurs when the target device has changed from a constant current (CC) mode to a constant voltage (CV) mode, or if the received state of the target device indicates that the target device has changed from the CC mode to the CV mode, the controller controls the operation for the wireless power transmission by reducing the output power.

9. The wireless power transmitter of claim 1 , wherein a plurality of target devices are provided, the controller receives states of the plurality of target devices, respectively, from the plurality of target devices, and determines the state of the wireless power transmission based on the received states and the change in the current.

10. The wireless power transmitter of claim 9 , wherein, in response to the current being reduced, and

in response to the received states of the target devices comprising at least one of a state indicating that a part of, or all of the target devices are changed in charging state from a constant current (CC) mode to a CV mode, a state indicating that at least one target device is removed from among the target devices, and a state indicating that at least one target device among the target devices is completely charged,

the controller controls the operation for the wireless power transmission by reducing the output power that is transmitted to the target devices.

11. The wireless power transmitter of claim 9 , wherein, in response to the current being increased and a target device being added to the target devices, the controller controls the operation for the wireless power transmission by increasing the output power so that the output power is transmitted to the added target device.

12. A method of controlling a wireless power transmission, the method comprising:

wirelessly transmitting an output power to a target device;

detecting a change in a current of the output power;

determining a state of a wireless power transmission based on the detected change in the current; and

controlling an operation for the wireless power transmission based on the determined state of the wireless power transmission.

13. The method of claim 12 , further comprising receiving a state of the target device from the target device, wherein the determining comprises determining the state of the wireless power transmission based on the detected change in the current and the received state of the target device.

14. The method of claim 12 , wherein, in response to the current being changed within a predetermined period of time, the current is determined to remain unchanged.

15. The method of claim 12 , wherein, in response to the current being changed within a predetermined range, the current is determined to remain unchanged.

16. The method of claim 12 , further comprising:

requesting the target device to transmit a state of the target device, in response to the current being changed for more than a predetermined period of time.

17. The method of claim 14 , wherein the controlling comprises adjusting the output power based on the received state of the target device.

18. The method of claim 12 , wherein the controlling comprises interrupting an output of the output power, in response to the current being changed to a current corresponding to a load indicating that the target device has been removed.

19. The method of claim 14 , wherein, in response to the current corresponding to a load that occurs when the target device has changed from a constant current (CC) mode to a constant voltage (CV) mode, or if the received state of the target device indicates that the target device has changed from the CC mode to the CV mode,

the controlling comprises controlling the operation for the wireless power transmission by reducing the output power.

20. The method of claim 12 , wherein a plurality of target devices are provided, the receiving comprises receiving states of the plurality of target devices, respectively, from the plurality of target devices, and the determining comprises determining the state of the wireless power transmission based on the received states and the change in the current.

21. The method of claim 20 , wherein, in response to the current being reduced, and

in response to the states of the target devices comprising at least one of a state indicating that a part of, or all of the target devices are changed in charging state from a constant current (CC) mode to a CV mode, a state indicating that at least one target device is removed from among the target devices, and a state indicating that at least one target device among the target devices is completely charged,

the controlling comprises controlling the operation for the wireless power transmission by reducing the output power.

22. The method of claim 20 , wherein, in response to the current being increased, and a target device being added to the target devices, the controlling comprises increasing the output power so that the output power is transmitted to the added target device.

23. A computer-readable storage medium having stored therein instructions to cause a processor to implement a method of controlling a wireless power transmission, the method comprising:

wirelessly transmitting an output power to a target device;

detecting a change in a current of the output power;

determining a state of a wireless power transmission based on the detected change in the current; and

controlling an operation for the wireless power transmission based on the determined state of the wireless power transmission.