Method of generating load variation for detecting wireless power receiving unit in wireless charging, and wireless power receiving unit

1. A method for detecting a wireless power receiver in a wireless power transmitter, the method comprising:

transmitting a time set value that is set for checking cross connection to the wireless power receiver;

detecting a load variation of the wireless power receiver;

determining whether the time set value is coincident with a load variation period

determining that the wireless power receiver is cross-connected, if the time set value is not coincident with the load variation period; and

transmitting a power receiving unit (PRU) control signal with permission denied due to cross connection.

2. The method of claim 1 , further comprising:

transmitting power to the wireless power receiver, if the time set value is coincident with the load variation period.

3. A wireless power transmitter comprising:

a communication module configured to transmit a time set value that is set for checking cross connection to the wireless power receiver; and

a controller configured to:

detect a load variation of the wireless power receiver,

determine whether the time set value is coincident with a load variation period

determine that the wireless power receiver is cross-connected, if the time set value is not coincident with the load variation period; and

transmit, through the communication module, a power receiving unit (PRU) control signal with permission denied due to cross connection.

4. The wireless power transmitter of claim 3 , further comprising

a power transmitter, and,

wherein the controller is further configured to transmit, through the power transmitter, power, if the time set value is coincident with the load variation period.

5. A method of generating a load variation in a wireless power receiver, the method comprising:

receiving, by a power receiver, power from a wireless power transmitter;

receiving, from the wireless power transmitter, a time set value that is set for checking cross connection;

in response to the receiving the time set value, generating a load variation by converting a load status from a first load status to a second load status; and

maintaining the second load status for a time corresponding to the received time set value.

6. The method of claim 5 , further comprising:

returning to the first load status, upon a lapse of the time corresponding to the received time set value.

7. The method of claim 5 , further comprising:

switching a switch connected to a dummy load to an ON state upon receiving the time set value and maintaining the ON state for the time corresponding to the received time set value.

8. The method of claim 7 , further comprising:

switching the switch to an OFF state, upon a lapse of time corresponding to the received time set value.

9. The method of claim 5 , wherein the load variation causes a power variation in the wireless power receiver.

10. A wireless power receiver comprising:

a power receiver configured to receive power from a wireless power transmitter;

a communication module configured to receive, from the wireless power transmitter, a time set value that is set for checking cross connection; and

a controller configured to:

generate a load variation by switching from a first load status to a second load status, and

maintain the second load status for a time corresponding to the received time set value.

11. The wireless power receiver of claim 10 , wherein the controller is further configured to return to the first load status, upon a lapse of the time corresponding to the received time set value.

12. The wireless power receiver of claim 10 , further comprising:

a dummy load connected in parallel between the power receiver and a load of the wireless power receiver; and

a switch configured to selectively connect the dummy load to the power receiver.

13. The wireless power receiver of claim 12 , wherein the controller is further configured to generate the load variation by switching the switch from an OFF state to an ON state and to maintain the ON state for the time corresponding to the received time set value.

14. The wireless power receiver of claim 13 , wherein the controller is further configured to return to the first load status by switching the switch from the ON state to the OFF state, upon a lapse of the time corresponding to the received time set value.

15. The wireless power receiver of claim 10 , wherein the load variation causes a power variation of the power receiver.