Wireless power feeder, wireless power transmission system, and table and table lamp using the same

• US 8,772,977 B2
• Filed: 04/28/2011
• Issued: 07/08/2014
• Est. Priority Date: 08/25/2010
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Urano, Takashi
• Primary Examiner(s): KAPLAN, HAL IRA
• Application Number:
  US13/096,526
• Publication Number:
  US 20120049641A1
• Time in Patent Office: 1,167 Days
• Field of Search: 307/104
• US Class Current: 307/104
• CPC Class Codes: B60L 53/122 Circuits or methods for driving the primary coil, e.g. supplying electric power to the coil
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

Power is fed from a feeding coil to a receiving coil by magnetic resonance. A drive circuit outputs an IN signal generated by an oscillator as a DR signal to alternately turn ON/OFF switching transistors at a resonance frequency, whereby AC current is fed to the feeding coil, and then the AC current is fed from the feeding coil to the receiving coil. An enable signal generation circuit generates an EN signal at a frequency lower than the resonance frequency. The drive circuit outputs the DR signal only while the EN signal assumes a high level. Transmission power from a wireless feeder to a wireless receiver is controlled by adjusting the duty ratio of the EN signal.

Claims

1. A wireless power feeder for feeding power from a feeding coil to a receiving coil by wireless using a magnetic field resonance phenomenon between the feeding coil and receiving coil, comprising:

a feeding coil;

a power transmission control circuit that feeds AC power to the feeding coil;

a control signal generation circuit that generates a control signal having a control frequency; and

a comparison circuit that generates an enable signal when a predetermined magnitude relationship is established between the level of the control signal and that of a reference signal, wherein

the power transmission control circuit feeds the AC power to the feeding coil under only while the enable signal is being generated.

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

the control signal generation circuit generates a signal having a saw-tooth waveform as the control signal.

3. The wireless power feeder according to claim 1, further comprising a reference signal adjustment circuit for adjusting the level of the reference signal.

4. The wireless power feeder according to claim 1, further comprising an exciting coil that is magnetically coupled to the feeding coil and feeds AC power fed from the power transmission control circuit to the feeding coil, wherein

the power transmission control circuit includes first and second current paths and makes first and second switches connected in series respectively to the first and second current paths alternately conductive to feed the AC power to the exciting coil.

5. The wireless power feeder according to claim 1, wherein

the power transmission control circuit makes the feeding coil that does not substantially resonate with circuit elements on the power feeding side feed the AC power to the receiving coil.

6. The wireless power feeder according to claim 1, wherein

the power feeding coil does not form, together with the circuit elements on the power feeding side, a resonance circuit having a resonance point corresponding to the resonance frequency of the receiving coil.

7. The wireless power feeder according to claim 1, wherein

no capacitor is inserted in series or in parallel to the power feeding coil.

8. The wireless power feeder according to claim 1, wherein

the feeding coil is connected to a capacitor and form a circuit which resonates at a resonance frequency of the receiving coil.

9. A wireless power transmission system comprising:

the wireless power feeder as claimed in claim 1;

the receiving coil; and

a loading coil that is magnetically coupled to the receiving coil and receives power that the receiving coil has received from the feeding coil.

10. The wireless power transmission system according to claim 9, wherein

the receiving coil is connected to a capacitor and form a circuit which resonates at a resonance frequency of the feeding coil.

11. A table with wireless power feeding function comprising the wireless power feeder as claimed in claim 1, wherein

the feeding coil is provided on the rear surface of the table or incorporated inside the table.

12. A table lamp with wireless power receiving function that receives, using a receiving coil, AC power transmitted from the table as claimed in claim 11 by wireless, comprising:

a receiving coil circuit that includes the receiving coil and a capacitor; and

a loading circuit that includes a loading coil that is magnetically coupled to the receiving coil to receive the AC power from the receiving coil and a lamp that receives power from the loading coil, wherein

when the lamp is placed on the table, the receiving coil receives the AC power fed from the feeding coil provided in the table to turn on the lamp.