Apparatus and method for detecting foreign object in wireless power transmitting system

1. A wireless power transmitting apparatus, comprising:

a primary coil;

an electric driving unit coupled to the primary coil; and

a control unit configured to:

receive a foreign object detection status packet from a wireless power receiving apparatus;

obtain, from the wireless power receiving apparatus, a reference value indicating an expected amount of power at the primary coil for a foreign object detection, the reference value being experimentally measured under controlled conditions of the wireless power receiving apparatus when no foreign object is present;

cause the electric driving unit to transmit to generate an alternating current (AC) signal at an initial setting for the foreign object detection,

measure an initial transmission power transferred from at the primary coil while the AC signal at the initial setting is applied to the primary coil, and

detect a foreign object based on the initial transmission power being larger than the reference value.

2. The wireless power transmitting apparatus of claim 1 , wherein the control unit is further configured to:

refrain from entering a power transfer phase in response to detecting the foreign object.

3. The wireless power transmitting apparatus of claim 1 , wherein the control unit is further configured to:

determine that an initial voltage of an output terminal of the wireless power receiving apparatus connected to an external load is at a steady state within a range of a reference voltage before measuring the initial transmission power.

4. The wireless power transmitting apparatus of claim 1 , wherein the control unit is further configured to:

perform a digital ping via the primary coil during a ping phase, and

receive identification and configuration information from the wireless power receiving apparatus after the ping phase and before the power transfer phase, wherein the identification and configuration information includes the reference value.

5. The wireless power transmitting apparatus of claim 1 , wherein the foreign object detection status packet is associated with initiating the foreign object detection by the wireless power transmitting apparatus before the power transfer phase.

6. A method of a wireless power transmitting apparatus equipped with a primary coil, the method comprising:

receiving a foreign object detection status packet from a wireless power receiving apparatus;

obtaining, from the wireless power receiving apparatus, a reference value indicating an expected amount of power at the primary coil for a foreign object detection, the reference value being experimentally measured under controlled conditions of the wireless power receiving apparatus when no foreign object is present;

causing an electric driving unit of the wireless power transmitting apparatus to generate an alternating current (AC) signal at an initial setting for the foreign object detection;

measuring an initial transmission power at the primary coil while the AC signal at the initial setting is applied to the primary coil; and

detecting a foreign object based on the initial transmission power being larger than the reference value.

7. The method of claim 6 , further comprising:

refraining from entering a power transfer phase in response to detecting the foreign object.

8. A wireless power transmitting apparatus comprising:

a primary coil configured to transmit wireless power via a magnetic field using an alternating current (AC) signal;

an electric driving unit connected to the primary coil and configured to generate the AC signal; and

a control unit configured to perform a foreign object detection (FOD) in which the control unit is configured to:

cause the electric drive unit to initially generate the AC signal as an FOD power signal, wherein the FOD power signal has an initial voltage that is lower than a power transmission voltage of a wireless power transfer power signal for a transfer of wireless power to a wireless power receiving apparatus;

determine that a foreign object is present in the magnetic field based on a first value measured at the primary coil during the FOD being higher than a reference value received from the wireless power reception apparatus, wherein the reference value indicates an expected amount of power at the primary coil for the FOD, the reference value being experimentally measured under controlled conditions of the wireless power receiving apparatus when no foreign object is present; and

refrain from entering into a power transfer phase after a determination that the foreign object is present in the magnetic field.

9. A wireless power transmitting apparatus, comprising:

a primary coil configured to transmit wireless power to a secondary coil in a wireless power receiving apparatus; and

a control unit configured to manage transmission of the wireless power via the primary coil, the control unit configured to:

receive identification and configuration information from the wireless power receiving apparatus;

cause the primary coil to transmit a power signal at an initial voltage;

measure, as a first value, an amount of power at the primary coil;

determine that a foreign object is present if the first value is larger than a reference value, the reference value indicating an expected amount of power at the primary coil when no foreign object is present, wherein the reference value is based on experimental measurements under controlled conditions of the wireless power receiving apparatus when no foreign object is present;

determine that the foreign object is not present if the first value is less than or equal to the reference value; and

refrain from transferring wireless power to the wireless power receiving apparatus based on a determination that the foreign object is present.

10. The wireless power transmitting apparatus of claim 9 , wherein the control unit is configured to receive the reference value from the wireless power receiving apparatus.