Method for controlling power transmitting device, method for detecting foreign object, and power transmitting device in wireless power transmission system

1. A method for detecting a metal foreign object using a power transmitting device, the power transmitting device including:

an inverter that generates power;

a power transmitting coil for outputting power to a power receiving coil included in a mobile object;

a thermal sensor that measures a surface temperature of the metal foreign object on the power transmitting coil; and

a power transmission control circuitry that causes the inverter to control the power output from the power transmitting coil;

the method comprising causing the power transmission control circuitry to:

cause the power transmitting coil to output the power before the power receiving coil and the power transmitting coil are electromagnetically coupled with each other and the mobile object overlaps the power transmitting coil;

cause the thermal sensor to measure a temperature distribution in a target area including the metal foreign object on the power transmitting coil; and

transmit, if the measured surface temperature of the metal foreign object is equal to or higher than a threshold, information indicating a relative positional relationship between the power transmitting coil and the metal foreign object on the basis of the measured temperature distribution.

2. The method according to claim 1 ,

wherein the power output from the power transmitting coil includes first power for detecting the metal foreign object and second power to be transmitted from the power transmitting coil to the power receiving coil,

wherein the first power is smaller than the second power,

wherein the power transmitting coil is caused to output the first power before the mobile object including the power receiving coil overlaps the power transmitting coil, and

wherein the thermal sensor is caused to measure the surface temperature of the metal foreign object while the first power is being output.

3. The method according to claim 1 ,

wherein the power transmitting device further includes a position sensor that measures a distance between the mobile object and the power transmitting coil or a position of the mobile object, and

wherein it is determined on the basis of a result of the measurement performed by the position sensor that the power receiving coil does not overlap the power transmitting coil.

4. The method according to claim 1 ,

wherein the information is transmitted to another receiving apparatus which is an information device installed in the mobile object, an information device carried by a user of the mobile object or a caretaker, or a control device that controls the power transmitting device.

5. The method according to claim 1 ,

wherein the information is transmitted to another receiving apparatus which includes an automotive navigation system, a smartphone, a tablet computer, a vehicle, a robot, or a controller included in a control device that controls the power transmitting device.

6. The method according to claim 1 ,

wherein at least either the power transmitting device or the mobile object includes a foreign object removal mechanism, and

wherein, if the measured surface temperature of the metal foreign object is equal to or higher than the threshold, the foreign object removal mechanism of at least either the power transmitting device or the mobile object is caused to perform an operation for removing a foreign object.

7. The method according to claim 6 ,

wherein, after the operation for removing a foreign object is performed, whether the metal foreign object has been actually removed is detected, and a signal indicating a result of the detection is transmitted to another receiving apparatus.

8. The method according to claim 6 ,

wherein the power transmitting device and the mobile object each include a foreign object removal mechanism,

wherein, if the measured surface temperature of the metal foreign object is equal to higher than the threshold, one of the foreign object removal mechanism of the power transmitting device and the mobile object is caused to perform the operation for removing a foreign object,

wherein, after the operation for removing a foreign object is performed, whether the metal foreign object has been actually removed is detected, and

wherein, if the metal foreign object has not been removed, the other foreign object removal mechanism of the power transmitting device and the mobile object is caused to perform another operation for removing a foreign object.

9. The method according to claim 1 ,

wherein, if the measured surface temperature of the metal foreign object is equal to or higher than the threshold, the power transmitting coil is caused to reduce the power or stop outputting the power.

10. The method according to claim 1 ,

wherein, after the power transmitting device transmits a first signal indicating the presence of the metal foreign object to a receiving apparatus, the receiving apparatus receives the first signal and transmits, to the power transmitting device, a second signal for reducing the power or stopping outputting the power, and

wherein, upon receiving the second signal, the power transmitting device reduces the power or stops outputting the power.

11. A power transmitting device comprising:

an inverter that generates power;

a power transmitting coil that transmits the power wirelessly to a power receiving coil included in a power receiving device in a mobile object;

a thermal sensor that measures a surface temperature of a metal foreign object on the power transmitting coil; and

a power transmission control circuitry that causes the inverter to control the power output from the power transmitting coil,

causes the power transmitting coil to output the power before the power receiving coil and the power transmitting coil are electromagnetically coupled with each other and the mobile object overlaps the power transmitting coil,

causes the thermal sensor to measure a temperature distribution in a target area including the metal foreign object on the power transmitting coil, and

transmits, if the measured surface temperature of the metal foreign object is equal to or higher than a threshold, information indicating a relative positional relationship between the power transmitting coil and the metal foreign object on the basis of the measured temperature distribution.

12. A method for detecting a metal foreign object using a power transmission device, the power transmission device including:

an inverter that generates power;

a power transmitting coil for outputting power to a power receiving coil included in a mobile object;

a thermal sensor that detects a surface temperature of the metal foreign object on the power transmitting coil;

a foreign object removal mechanism; and

a power transmission control circuitry that causes the inverter to control the power output from the power transmitting coil;

the method comprising causing the power transmission control circuitry to:

cause the power transmitting coil to output the power to heat the metal foreign object before the power receiving coil and the power transmitting coil are electromagnetically coupled with each other and the mobile object overlaps the power transmitting coil;

cause the thermal sensor to measure the surface temperature of the heated metal foreign object; and

causing, if the measured surface temperature of the metal foreign object is equal to or higher than a threshold, the foreign object removal mechanism to perform an operation for removing a foreign object.

13. The method according to claim 12 ,

wherein, after the operation for removing a foreign object is performed, whether the metal foreign object has been actually removed is detected, and a signal indicating a result of the detection is transmitted to a receiving apparatus other than the power transmitting device.