Wireless power transmitting device, wireless power receiving device, and wireless power transmission system
An object of the present invention is to reduce the possibility of failure in the detection of metallic foreign object. A metallic foreign object detector includes a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal a vibration time length measurement circuit that measures a vibration time length indicating the length of time required for the vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1, and a determination circuit that determines the presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is the vibration time length obtained in the absence of the approaching metallic foreign object.
1. A wireless power transmitting device that transmits power by wireless from a feeding coil to a receiving coil, the wireless power transmitting device comprising:
the feeding coil; and
a metallic foreign object detector,
wherein the metallic foreign object detector includes:
a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1; and
a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object, and
wherein a measurement time of the vibration time length is less than a period of a power transmission frequency.
2. The wireless power transmitting device as claimed in claim 1 , further comprising a noise detection part that detects noise vibrating at a frequency higher than a frequency used in a power transmission,
wherein the metallic foreign object detector further comprises a control circuit that determines at least one of a measurement start point of the vibration time length and the predetermined wavenumber based on a noise detection result from the noise detection part, and that sets the at least one of the measurement start point of the vibration time length and the predetermined wavenumber to the vibration time length measurement circuit.
3. The wireless power transmitting device as claimed in claim 1 , wherein the metallic foreign object detector further comprises:
a drive circuit that applies voltage to the at least one antenna coil;
a detection circuit that measures the power transmission frequency and detects a phase of voltage generated in the at least one antenna coil by a power transmission; and
a control circuit that controls a timing of a voltage application performed by the drive circuit based on the power transmission frequency measured by the detection circuit and the phase of voltage detected by the detection circuit.
4. A wireless power receiving device that transmits power by wireless from a feeding coil to a receiving coil, the wireless power receiving device comprising:
the receiving coil; and
a metallic foreign object detector,
wherein the metallic foreign object detector includes:
a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1; and
a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object, and
wherein a measurement time of the vibration time length is less than a period of a power transmission frequency.
5. The wireless power receiving device as claimed in claim 4 , further comprising a noise detection part that detects noise vibrating at a frequency higher than a frequency used in a power transmission,
wherein the metallic foreign object detector further comprises a control circuit that determines at least one of a measurement start point of the vibration time length and the predetermined wavenumber based on a noise detection result from the noise detection part, and that sets the at least one of the measurement start point of the vibration time length and the predetermined wavenumber to the vibration time length measurement circuit.
6. The wireless power receiving device as claimed in claim 4 , wherein the metallic foreign object detector further comprises:
a drive circuit that applies voltage to the at least one antenna coil;
a detection circuit that measures the power transmission frequency and detects a phase of voltage generated in the at least one antenna coil by a power transmission; and
a control circuit that controls a timing of a voltage application performed by the drive circuit based on the power transmission frequency measured by the detection circuit and the phase of voltage detected by the detection circuit.
7. A wireless power transmission system that transmits power by wireless from a feeding coil to a receiving coil, the wireless power transmission system comprising:
a wireless power transmitting device having the feeding coil; and
a wireless power receiving device having the receiving coil,
wherein at least one of the wireless power transmitting device and wireless power receiving device has a metallic foreign object detector,
wherein the metallic foreign object detector includes:
a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1; and
a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object, and
wherein a measurement time of the vibration time length is less than a period of the power transmission frequency.
8. The wireless power transmission system as claimed in claim 7 , further comprising a noise detection part that detects noise vibrating at a frequency higher than a frequency used in a power transmission,
wherein the metallic foreign object detector further comprises a control circuit that determines at least one of a measurement start point of the vibration time length and the predetermined wavenumber based on a noise detection result from the noise detection part, and that sets the at least one of the measurement start point of the vibration time length and the predetermined wavenumber to the vibration time length measurement circuit.
9. The wireless power transmission system as claimed in claim 7 , wherein the metallic foreign object detector further comprises:
a drive circuit that applies voltage to the at least one antenna coil;
a detection circuit that measures the power transmission frequency and detects a phase of voltage generated in the at least one antenna coil by a power transmission; and
a control circuit that controls a timing of a voltage application performed by the drive circuit based on the power transmission frequency measured by the detection circuit and the phase of voltage detected by the detection circuit.
10. The wireless power transmitting device as claimed in claim 1 , wherein a start point of a measurement of vibration time length by the vibration time length measurement circuit is made freely adjustable.
11. The wireless power transmitting device as claimed in claim 1 , wherein the predetermined wavenumber is made freely adjustable.
12. The wireless power receiving device as claimed in claim 4 , wherein a start point of a measurement of vibration time length by the vibration time length measurement circuit is made freely adjustable.
13. The wireless power receiving device as claimed in claim 4 , wherein the predetermined wavenumber is made freely adjustable.
14. The wireless power transmission system as claimed in claim 7 , wherein a start point of a measurement of vibration time length by the vibration time length measurement circuit is made freely adjustable.
15. The wireless power transmission system as claimed in claim 7 , wherein the predetermined wavenumber is made freely adjustable.
16. A wireless power transmitting device that transmits power by wireless from a feeding coil to a receiving coil, the wireless power transmitting device comprising:
the feeding coil; and
a metallic foreign object detector,
wherein the metallic foreign object detector includes:
a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1;
a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object;
a drive circuit that applies voltage to the at least one antenna coil;
a detection circuit that measures a power transmission frequency and detects a phase of voltage generated in the at least one antenna coil by a power transmission; and
a control circuit that controls a timing of a voltage application performed by the drive circuit based on the power transmission frequency measured by the detection circuit and the phase of voltage detected by the detection circuit.
17. The wireless power transmitting device as claimed in claim 16 , further comprising a noise detection part that detects noise vibrating at a frequency higher than a frequency used in a power transmission,
wherein the metallic foreign object detector farther comprises a control circuit that determines at least one of a measurement start point of the vibration time length and the predetermined wavenumber based on a noise detection result from the noise detection part, and that sets the at least one of the measurement start point of the vibration time length and the predetermined wavenumber to the vibration time length measurement circuit.
18. A wireless power receiving device that transmits power by wireless from a feeding coil to a receiving coil, the wireless power receiving device comprising:
the receiving coil; and
a metallic foreign object detector,
wherein the metallic foreign object detector includes:
a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1;
a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object;
a drive circuit that applies voltage to the at least one antenna coil;
a detection circuit that measures a power transmission frequency and detects a phase of voltage generated in the at least one antenna coil by a power transmission; and
a control circuit that controls a timing of a voltage application performed by the drive circuit based on the power transmission frequency measured by the detection circuit and the phase of voltage detected by the detection circuit.
19. The wireless power receiving device as claimed in claim 18 , further comprising a noise detection part that detects noise vibrating at a frequency higher than a frequency used in a power transmission,
wherein the metallic foreign object detector further comprises a control circuit that determines at least one of a measurement start point of the vibration time length and the predetermined wavenumber based on a noise detection result from the noise detection part, and that sets the at least one of the measurement start point of the vibration time length and the predetermined wavenumber to the vibration time length measurement circuit.
20. A wireless power transmission system that transmits power by wireless from a feeding coil to a receiving coil, the wireless power transmission system comprising:
a wireless power transmitting device having the feeding coil; and
a wireless power receiving device having the receiving coil,
wherein at least one of the wireless power transmitting device and wireless power receiving device has a metallic foreign object detector, and
wherein the metallic foreign object detector includes:
a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1;
a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object;
a drive circuit that applies voltage to the at least one antenna coil;
a detection circuit that measures a power transmission frequency and detects a phase of voltage generated in the at least one antenna coil by a power transmission; and
a control circuit that controls a timing of a voltage application performed by the drive circuit based on the power transmission frequency measured by the detection circuit and the phase of voltage detected by the detection circuit.
21. The wireless power transmission system as claimed in claim 20 , further comprising a noise detection part that detects noise vibrating at a frequency higher than a frequency used in a power transmission,
wherein the metallic foreign object detector further comprises a control circuit that determines at least one of a measurement start point of the vibration time length and the predetermined wavenumber based on a noise detection result from the noise detection part, and that sets the at least one of the measurement start point of the vibration time length and the predetermined wavenumber to the vibration time length measurement circuit.
22. The wireless power transmitting device as claimed in claim 16 , wherein a start point of a measurement of vibration time length by the vibration time length measurement circuit is made freely adjustable.
23. The wireless power transmitting device as claimed in claim 16 , wherein the predetermined wavenumber is made freely adjustable.
24. The wireless power receiving device as claimed in claim 18 , wherein a start point of a measurement of vibration time length by the vibration time length measurement circuit is made freely adjustable.
25. The wireless power receiving device as claimed in claim 18 , wherein the predetermined wavenumber is made freely adjustable.
26. The wireless power transmission system as claimed in claim 20 , wherein a start point of a measurement of vibration time length by the vibration time length measurement circuit is made freely adjustable.
27. The wireless power transmission system as claimed in claim 20 , wherein the predetermined wavenumber is made freely adjustable.