WIRELESS POWER TRANSFER DEVICE AND WIRELESS POWER TRANSFER METHOD

• US 20130082535A1
• Filed: 03/07/2012
• Published: 04/04/2013
• Est. Priority Date: 09/29/2011
• Status: Active Grant

• Current Assignee: Maxell, Ltd.
• Original Assignee: Yasushi Miyauchi
• Inventors: MIYAUCHI, Yasushi, Onuki, Satoru
• Granted Patent: US 9,172,436 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: B60L 53/126 Methods for pairing a vehicle and a charging station, e.g. establishing a one-to-one relation between a wireless power transmitter and a wireless power receiver
• CPC Class Codes: H04B 5/266 One coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer
• 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

A wireless power transfer device including: a power transmitter 1 including a power transmission resonator composed of a power transmission coil and a resonant capacitance; and a power receiver including a power receiving resonator composed of a power receiving coil and a resonant capacitance. The wireless power transfer device further includes a power-transmission auxiliary device including an auxiliary resonator composed of an auxiliary coil and a resonant capacitance. The power-transmission auxiliary device and the power transmitter are configured to be disposed so as to face each other, forming a power receiving space for disposing the power receiving coil between the power transmission coil and the auxiliary coil. An efficient power transfer can be performed without providing an adjusting circuit in the power receiver even when the power receiving coil is not appropriately disposed with respect to the power transmission coil.

Claims

1. A wireless power transfer device comprising:

a power transmitter including a power transmission resonator composed of a power transmission coil and a resonant capacitance; and

a power receiver including a power receiving resonator composed of a power receiving coil and a resonant capacitance,

thereby transferring power from the power transmitter to the power receiver through an interaction between the power transmission coil and the power receiving coil,

further comprising;

a power-transmission auxiliary device including an auxiliary resonator composed of an auxiliary coil and a resonant capacitance,

wherein the power-transmission auxiliary device and the power transmitter are configured to be disposed so as to face each other, forming a power receiving space for disposing the power receiving coil between the power transmission coil and the auxiliary coil.

2. The wireless power transfer device according to claim 1, wherein an electric power is transferred from the power transmitter to the power receiver through magnetic field resonance between the power transmission coil and the power receiving coil.

3. The wireless power transfer device according to claim 1, wherein a resonant frequency f3 of the auxiliary resonator is set such that a resonant frequency ft of a power transmission-side resonant system composed of the power transmission resonator and the auxiliary resonator coincides with a resonant frequency f2 of the power receiving resonator.

4. The wireless power transfer device according to claim 1, wherein an adjusting variable capacitor is provided as the resonant capacitance of the power-transmission auxiliary device, and a resonant frequency f3 of the auxiliary resonator is set by adjusting the adjusting variable capacitor.

5. The wireless power transfer device according to claim 1, wherein a diameter d1 of the power transmission coil, a diameter d2 of the power receiving coil, and a diameter d3 of the auxiliary coil satisfy the relationship:

d1>

d2, and d2<

d3.

6. The wireless power transfer device according to claim 5, wherein the relationship:

d1=d3, and d1>

d2 is satisfied.

7. The wireless power transfer device according to claim 5, wherein a central axis of the power transmission coil, a central axis of the auxiliary coil, and a central axis of the power receiving coil are arranged to be coaxial.

8. The wireless power transfer device according to claim 1, wherein a resonant frequency f1 of the power transmission resonator, a resonant frequency f2 of the power receiving resonator, and a resonant frequency f3 of the auxiliary resonator are set so as to satisfy the relationship:

f1=f2<

f3, or f3<

f1=f2.

9. The wireless power transfer device according to claim 1, wherein a resonant frequency f1 of the power transmission resonator, a resonant frequency f2 of the power receiving resonator, and a resonant frequency f3 of the auxiliary resonator are set so as to satisfy the relationship:

f2<

f1=f3, or f1=f3<

f2.

10. The wireless power transfer device according to claim 1,

further comprising:

a casing that holds the power transmitter and the power-transmission auxiliary device and is configured to be capable of setting a positional relationship between the power transmitter and the power-transmission auxiliary device so as to form the power receiving space,

wherein the power receiver can be removably placed in the power receiving space,

the casing is provided with a lid that can be opened and closed, and power transfer from the power transmission coil to the power receiving coil is performed with the lid being closed, and

an area surrounding the power transmission coil, the auxiliary coil, and the power receiving coil is electromagnetically shielded during power transfer from the power transmission coil to the power receiving coil.

11. The wireless power transfer device according to claim 10,

wherein the casing is provided with an interlock function for maintaining a state of power transfer from the power transmitter to the power receiver, and

the interlock function maintains a condition of electromagnetically shielding an area surrounding the power transmission coil, the auxiliary coil, and the power receiving coil during power transfer.

12. A wireless power transfer method using:

a power transmitter including a power transmission resonator composed of a power transmission coil and a resonant capacitance, and a power receiver including a power receiving resonator composed of a power receiving coil and a resonant capacitance, thereby transferring an electric power from the power transmitter to the power receiver through an interaction between the power transmission coil and the power receiving coil,

wherein the method further uses a power-transmission auxiliary device including an auxiliary resonator composed of an auxiliary coil and a resonant capacitance, and

the method comprising;

disposing the power-transmission auxiliary device and the power transmitter so as to face each other, forming a power receiving space between the power transmission coil and the auxiliary coil, and

performing a power transfer with the power receiving coil being disposed in the power receiving space.

13. The wireless power transfer method according to claim 12,

wherein a variable capacitance is used as the resonant capacitance composing the auxiliary resonator, and

power transfer efficiency is adjusted by adjusting the variable capacitance while disposing the power receiving coil in the power receiving space.