Foreign object detecting device, wireless power transmitting apparatus, and wireless power transfer system

Patent metadata

Field	Value
Publication number	US-2016336759-A1
Application number	US-201615065931-A
Country	US
Kind code	A1
Filing date	Mar 10, 2016
Priority date	May 15, 2015
Publication date	Nov 17, 2016
Grant date	—

Abstract

A foreign object detecting device includes first, second, and third coils and a foreign object detecting circuit. The foreign object detecting circuit outputs a first detecting signal having a first predetermined waveform to a first terminal of the first coil and outputs a second detecting signal having a second predetermined waveform, which is an inverted form of the first predetermined waveform, to a fifth terminal of the third coil to cause a combined magnetic field extending over the first and third coils. The foreign object detecting circuit measures an amount of change of the impedance value of the first or third coil with respect to a change in the combined magnetic field in the case of the presence of a foreign object. The amount of change exceeds a predetermined value, the foreign object detecting circuit determines that there is a foreign object above the second coil.

First claim

What is claimed is:

1 . A foreign object detecting device comprising:
a first coil that includes a first wound wire having first and second terminals; a second coil that includes a second wound wire having third and fourth terminals and is disposed adjacent to the first coil; a third coil that includes a third wound wire having fifth and sixth terminals and is disposed adjacent to the second coil, the second coil being disposed between the first coil and the third coil, a winding direction of the third wound wire from the fifth terminal to the sixth terminal being the same as a winding direction of the first wound wire from the first terminal to the second terminal; and a foreign object detecting circuit operative to: output a first detecting signal having a first predetermined waveform to the first terminal of the first coil and output second detecting signal having a second predetermined waveform to the fifth terminal of the third coil to cause a combined magnetic field extending over the first and third coils, a polarity of the second predetermined waveform being an inverted polarity of the first predetermined waveform; measure an amount of change of an impedance value with respect to one of the first and third coils corresponding to a change in the combined magnetic field which is caused by presence of a foreign object; and determine that a foreign object above the second coil is present if the amount of change exceeds a predetermined value, wherein potential of each of the second, fourth, and sixth terminals is at the same as reference potential of the foreign object detecting circuit.

2 . The foreign object detecting device according to claim 1 , wherein:
each of the first, third, and fifth terminals is one of an outer terminal disposed on an outer side of a corresponding one of the first, second, and third coils and an inner terminal disposed on an inner side of a corresponding one of the first, second, and third coils; and each of the second, fourth, and sixth terminals is the other one of the outer terminal and the inner terminal of a corresponding one of the first, second, and third coils.

3 . The foreign object detecting device according to claim 1 , wherein a winding direction of the second wound wire of the second coil from the third terminal to the fourth terminal is the same as the winding direction of the first wound wire of the first coil from the first terminal to the second terminal.

4 . The foreign object detecting device according to claim 1 , wherein
the foreign object detecting circuit measures an amount of change of an impedance value of the first and third coils connected with each other with respect to a change in the combined magnetic field in the case of the presence of a foreign object, and determines that a foreign object is present above the second coil if the amount of change exceeds a predetermined value.

5 . The foreign object detecting device according to claim 1 , wherein each of the first, second, and third coils is disposed in a direction perpendicular to an axis of a corresponding one of the first, second, and third coils.

6 . The foreign object detecting device according to claim 1 , wherein the first and second detecting signals are alternating current signals or pulse signals.

7 . The foreign object detecting device according to claim 1 , wherein the foreign object detecting circuit simultaneously outputs the first and second detecting signals to the first and third coils, respectively.

8 . The foreign object detecting device according to claim 1 , further comprising:
four or more coils including the first, second, and third coils and one or more coils having the same structure as a structure of the first and third coils; and at least one switch that electrically connects the first and third coils among the four or more coils to the foreign object detecting circuit, wherein, before outputting the first and second detecting signals, the foreign object detecting circuit selects the first and third coils among the four or more coils by using the at least one switch, as two coils disposed adjacent to both sides of one coil.

9 . A wireless power transmitting apparatus comprising:
the foreign object detecting device according to claim 1 ; a power transmitting coil; and a power transmitting circuit that transmits high-frequency power to the power transmitting coil.

10 . The wireless power transmitting apparatus according to claim 9 , further comprising:
a housing within which the power transmitting coil is disposed, wherein an outer periphery of each of the first and third coils is smaller than an outer periphery of the power transmitting coil, and the first and third coils are disposed between a main surface of the housing and the power transmitting coil.

11 . The wireless power transmitting apparatus according to claim 9 , wherein the power transmitting coil and at least one of the first and third coils are the same component.

12 . The wireless power transmitting apparatus according to claim 9 , wherein power of the first detecting signal and power of the second detecting signal are lower than the high-frequency power.

13 . The wireless power transmitting apparatus according to claim 9 , further comprising:
a control circuit that causes the power transmitting circuit to transmit the high-frequency power after it is determined by the foreign object detecting circuit that there is no foreign object within a magnetic field formed by the first and third coils.

14 . The wireless power transmitting apparatus according to claim 9 , wherein the second coil and the power transmitting coil are the same component.

15 . A wireless power transfer system comprising:
the wireless power transmitting apparatus according to claim 9 ; and a wireless power receiving apparatus.

16 . A foreign object detecting device comprising:
a first coil that includes a first wound wire having first and second terminals; a second coil that includes a second wound wire having third and fourth terminals and is disposed adjacent to the first coil; a third coil that includes a third wound wire having fifth and sixth terminals and is disposed adjacent to the second coil, the second coil being disposed between the first coil and the third coil, a winding direction of the third wound wire from the fifth terminal to the sixth terminal being the same as a winding direction of the first wound wire from the first terminal to the second terminal; a foreign object detecting circuit that outputs a first detecting signal having a first predetermined waveform; and a phase shifter that converts the first detecting signal into a second detecting signal having a second predetermined waveform and outputs the second detecting signal to the fifth terminal of the third coil, a polarity of the second predetermined waveform being an inverted polarity of the first predetermined waveform, the foreign object detecting circuit operative to: output the first detecting signal to the first terminal of the first coil and to the phase shifter to cause a combined magnetic field extending over the first and third coils; measure an amount of change of a combined impedance value of the first and third coils with respect to a change in the combined magnetic field in the case of the presence of a foreign object; and determine that a foreign object above the second coil is present if the amount of change exceeds a predetermined value, wherein potential of each of the second, fourth, and sixth terminals is at the same as reference potential of the foreign object

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Yamamoto Atsushi
• Kanno Hiroshi

Classifications

• G01V3/101

  by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil (measuring impedance or characteristics derived therefrom G01R27/00, e.g. quality factor G01R27/26) · CPC title

• H02J5/005 Primary

  Electricity · mapped topic

• H02J50/60 Primary

  responsive to the presence of foreign objects, e.g. detection of living beings · CPC title