Wireless power transmission apparatus and supply power control method of wireless power transmission apparatus

• US 10,069,310 B2
• Filed: 05/28/2014
• Issued: 09/04/2018
• Est. Priority Date: 07/09/2013
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Tsuda, Hisashi, Hatanaka, Takezo
• Primary Examiner(s): Gannon, Levi
• Application Number:
  US14/904,147
• Publication Number:
  US 20160141885A1
• Time in Patent Office: 1,560 Days
• Field of Search: 307104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 7/00718 in response to charge current gradient

Abstract

A wireless power transmission apparatus which is charged in a short charging time and prevents the shortening of the life of a secondary battery is provided. A wireless power transmission apparatus includes a current-voltage detector configured to measure an input impedance Zin of the wireless power transmission apparatus including the power-supplied device and a control device configured to determine whether a constant current charging period (CC) is finished by utilizing a change in the input impedance Zin measured by the current-voltage detector and terminate the charging of the lithium ion secondary battery when it is determined that the constant current charging period (CC) is finished.

Claims

1. A wireless power transmission apparatus configured to supply power by resonance phenomenon from a power-supplying module connected with a power source to a power-receiving module connected with a power-supplied device including a secondary battery which is chargeable by a constant current-constant voltage charging system, the wireless power transmission apparatus comprising:

an input impedance measuring apparatus configured to measure an input impedance of the wireless power transmission apparatus including the power-supplied device; and

a control device configured to determine whether a constant current charging period is finished based on a change in the input impedance measured by the input impedance measuring apparatus, and terminate charging when it is determined that the constant current charging period is finished, wherein

the power-supplying module includes at least a power-supplying coil and a power-supplying resonator, and the power-receiving module includes at least a power-receiving resonator and a power-receiving coil, and

a load variation characteristic is adjustable by adjusting at least one of a coupling coefficient between the power-supplying coil and the power-supplying resonator, a coupling coefficient between the power-supplying resonator and the power-receiving resonator, and a coupling coefficient between the power-receiving resonator and the power-receiving coil.

2. The wireless power transmission apparatus according to claim 1, wherein, the control device determines that the constant current charging period is finished when the input impedance measured by the input impedance measuring apparatus becomes higher than or lower than a predetermined threshold.

3. The wireless power transmission apparatus according to claim 1, wherein, the control device determines that the constant current charging period is finished when the load variation characteristic becomes higher than or lower than a predetermined threshold, the load variation characteristic being an amount of change with respect to a charging time in the input impedance measured by the input impedance measuring apparatus.

4. The wireless power transmission apparatus according to claim 1, wherein, the load variation characteristic is increased by increasing the coupling coefficient between the power-supplying coil and the power-supplying resonator.

5. The wireless power transmission apparatus according to claim 1, wherein, the load variation characteristic is increased by increasing the coupling coefficient between the power-receiving resonator and the power-receiving coil.

6. The wireless power transmission apparatus according to claim 1, wherein, the load variation characteristic is increased by increasing the coupling coefficient between the power-supplying coil and the power-supplying resonator and the coupling coefficient between the power-receiving resonator and the power-receiving coil.

7. A supply power control method of a wireless power transmission apparatus for supplying, by changing a magnetic field, power from a power-supplying module connected with a power source to a power-receiving module connected with a power-supplied device including a secondary battery which is chargeable by a constant current-constant voltage charging system, the power-supplying module includes at least a power-supplying coil and a power-supplying resonator, and the power-receiving module includes at least a power-receiving resonator and a power-receiving coil, the wireless power transmission apparatus including:

an input impedance measuring apparatus configured to measure an input impedance of the power transmission apparatus; and

a control device, and

the control device being configured to execute the steps of;

determining whether a constant current charging period is finished, by utilizing a change in the input impedance measured by the input impedance measuring apparatus;

terminating charging when it is determined that the constant current charging period is finished; and

adjusting a load variation characteristic by adjusting at least one of a coupling coefficient between the power-supplying coil and the power-supplying resonator, a coupling coefficient between the power-supplying resonator and the power-receiving resonator, and a coupling coefficient between the power-receiving resonator and the power-receiving coil.