Wireless power apparatus and wireless power-receiving method

• US 8,482,159 B2
• Filed: 03/31/2010
• Issued: 07/09/2013
• Est. Priority Date: 03/31/2009
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Shimokawa, Satoshi
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): VU, TOAN T
• Application Number:
  US12/750,774
• Publication Number:
  US 20100244583A1
• Time in Patent Office: 1,196 Days
• Field of Search: None
• US Class Current: 307/104
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 5/263 Multiple coils at either side
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A wireless power apparatus includes: a power receiver coil which receives power, as magnetic field energy, from a power transmitter coil by magnetic field resonance produced between the power transmitter coil and the power receiver coil; a power pickup coil which derives power from the power receiver coil by electromagnetic induction; a detector which detects current flowing through the power pickup coil; and a controller which controls a coupling strength between the power pickup coil and the power receiver coil based on the current detected by the detector.

Claims

1. A wireless power apparatus comprising:

a power receiver coil which receives power, as magnetic field energy, from a power transmitter coil by magnetic field resonance produced between the power transmitter coil and the power receiver coil;

a power pickup coil which derives power from the power receiver coil by electromagnetic induction;

a detector which detects current flowing through the power pickup coil; and

a controller which controls a coupling strength between the power pickup coil and the power receiver coil based on the current detected by the detector.

2. The wireless power apparatus according to claim 1, wherein

the controller performs the control so that the coupling strength between the power pickup coil and the power receiver coil is increased in response to an increase in the current flowing through the power pickup coil, and the coupling strength between the power pickup coil and the power receiver coil is decreased in response to a decrease in the current flowing through the power pickup coil.

3. The wireless power apparatus according to claim 1, further comprising:

a driver which is capable of displacing the power pickup coil so that the coupling strength of the power receiver coil and the power pickup coil is changed, wherein

the controller controls the driver so that the power pickup coil is displaced based on the current detected by the detector.

4. The wireless power apparatus according to claim 1, wherein

the power pickup coil comprises:

a plurality of coils each having a different coupling strength relative to the power receiver coil; and

a switcher capable of selecting at least one of the plurality of coils, wherein

the controller controls switching of the switcher based on the current detected by the detector.

5. The wireless power apparatus according to claim 2, further comprising:

a driver which is capable of displacing the power pickup coil so that the coupling strength of the power receiver coil and the power pickup coil is changed, wherein

the controller controls the driver so that the power pickup coil is displaced based on the current detected by the detector.

6. The wireless power apparatus according to claim 2, wherein

the power pickup coil comprises:

a plurality of coils each having a different coupling strength relative to the power receiver coil; and

a switcher capable of selecting at least one of the plurality of coils, wherein

the controller controls switching of the switcher based on the current detected by the detector.

7. A wireless power-receiving method comprising:

supplying power, as magnetic field energy, to a power receiver coil from a power transmitter coil by use of magnetic field resonance produced between the power transmitter coil and the power receiver coil;

deriving power from the power receiver coil to the power pickup coil by electromagnetic induction;

detecting current flowing through the power pickup coil; and

controlling a coupling strength between the power pickup coil and the power receiver coil based on amplitude of the current detected by the detector.

8. The wireless power-receiving method according to claim 7, further comprising:

increasing the coupling strength between the power pickup coil and the power receiver coil in response to an increase in the current flowing through the power pickup coil, and decreasing the coupling strength between the power pickup coil and the power receiver coil in response to a decrease in the current flowing through the power pickup coil.

9. The wireless power-receiving method according to claim 7, further comprising:

controlling the coupling strength between the power receiver coil and the power pickup coil by displacing the power pickup coil.

10. The wireless power-receiving method according to claim 7, further comprising:

controlling the coupling strength between the power receiver coil and the power pickup coil by selecting at least one of a plurality of power pickup coils each having a different coupling strength relative to the power receiver coil.

11. The wireless power-receiving method according to claim 8, further comprising:

controlling the coupling strength between the power receiver coil and the power pickup coil by displacing the power pickup coil.

12. The wireless power-receiving method according to claim 8, further comprising:

controlling the coupling strength between the power receiver coil and the power pickup coil by selecting at least one of a plurality of power pickup coils each having a different coupling strength relative to the power receiver coil.