POWER TRANSMISSION DEVICE AND WIRELESS POWER TRANSMISSION SYSTEM INCLUDING THE SAME

• US 20120133212A1
• Filed: 11/18/2011
• Published: 05/31/2012
• Est. Priority Date: 11/26/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: KAMATA, Koichiro
• Granted Patent: US 9,461,476 B2
• Time in Patent Office: Days
• 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: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves

Abstract

Not a structure in which a resonance frequency of a power transmission device is set after a resonance frequency of a power receiving device is directly measured but a structure in which the resonance frequencies of the power receiving device and the power transmission device are estimated after reflection of an electromagnetic field for transmitting electric power to the power receiving device is monitored by the power transmission device is employed. After a capacitance value of a variable capacitor in a resonance coil of the power receiving device is once set to 0, an S11 parameter is detected while a frequency of an electromagnetic wave is changed, and the resonance frequency of the power transmission device is estimated on the basis of the S11 parameter.

Claims

1. A power transmission device comprising:

a first coil;

a first resonance coil;

a detector; and

a control device,

wherein the first coil is connected to a high-frequency power source through a coupler,

wherein the first resonance coil is connected to a variable capacitor and is electromagnetically coupled with the first coil, and electromagnetic resonance occurs between the first resonance coil and a second resonance coil electromagnetically coupled with a second coil in a power receiving device,

wherein the detector detects intensity of an S11 parameter output from the coupler, and

wherein the control device has a function of changing a capacitance value of the variable capacitor and an oscillation frequency of a signal output from the high-frequency power source, sets the capacitance value of the variable capacitor to 0, sets a frequency at which the intensity of the S11 parameter is changed at the time when the oscillation frequency of the signal output from the high-frequency power source is changed under a condition that the capacitance value of the variable capacitor is 0, as a resonance frequency of the second resonance coil, sets a resonance frequency of the first resonance coil after the capacitance value of the variable capacitor is set in accordance with the resonance frequency of the second resonance coil, and sets the oscillation frequency of the signal output from the high-frequency power source as the resonance frequencies of the first resonance coil and the second resonance coil.

2. The power transmission device according to claim 1, further comprising a memory circuit in which the capacitance value of the variable capacitor for setting the resonance frequency of the first resonance coil on the basis of the resonance frequency of the second resonance coil is stored, wherein the memory circuit is connected to the control device.

3. A power transmission device comprising:

a first coil;

a first resonance coil;

a detector; and

a control device,

wherein the first coil is connected to a high-frequency power source through a coupler,

wherein the first resonance coil is connected to a variable capacitor and is electromagnetically coupled with the first coil, and electromagnetic resonance occurs between the first resonance coil and a second resonance coil electromagnetically coupled with a second coil in a power receiving device,

wherein the detector detects intensity of an S11 parameter output from the coupler, and

wherein the control device has a function of changing a capacitance value of the variable capacitor and an oscillation frequency of a signal output from the high-frequency power source, sets the capacitance value of the variable capacitor to 0, sets a frequency at which the intensity of the S11 parameter is changed at the time when the oscillation frequency of the signal output from the high-frequency power source is changed under a condition that the capacitance value of the variable capacitor is 0, as a resonance frequency of the second resonance coil, sets a resonance frequency of the first resonance coil after the capacitance value of the variable capacitor is set in accordance with the resonance frequency of the second resonance coil, and sets a frequency at which the intensity of the S11 parameter is changed at the time when the oscillation frequency of the signal output from the high-frequency power source is changed under a condition that the capacitance value of the variable capacitor is set to a capacitance value based on the resonant frequency of the second resonance coil, as the oscillation frequency of the signal output from the high-frequency power source.

4. The power transmission device according to claim 3, further comprising a memory circuit in which the capacitance value of the variable capacitor for setting the resonance frequency of the first resonance coil on the basis of the resonance frequency of the second resonance coil is stored, wherein the memory circuit is connected to the control device.

5. A wireless power transmission system comprising a power transmission device and a power receiving device,

wherein the power transmission device comprising:

a first coil;

a first resonance coil;

a detector; and

a control device,

wherein the first coil is connected to a high-frequency power source through a coupler,

wherein the first resonance coil is electromagnetically coupled with the first coil and is connected to a variable capacitor,

wherein the detector detects intensity of an S11 parameter output from the coupler,

wherein the control device has a function of changing a capacitance value of the variable capacitor and an oscillation frequency of a signal output from the high-frequency power source, sets the capacitance value of the variable capacitor to 0, sets a frequency at which the intensity of the S11 parameter is changed at the time when the oscillation frequency of the signal output from the high-frequency power source is changed under a condition that the capacitance value of the variable capacitor is 0, as a resonance frequency of a second resonance coil, sets a resonance frequency of the first resonance coil after the capacitance value of the variable capacitor is set in accordance with the resonance frequency of the second resonance coil, and sets the oscillation frequency of the signal output from the high-frequency power source as the resonance frequencies of the first resonance coil and the second resonance coil, and

wherein the power receiving device includes the second resonance coil which causes electromagnetic resonance with the first resonance coil and is connected to a capacitor and a second coil which is electromagnetically coupled with the second resonance coil and is connected to a load.

6. The wireless power transmission system according to claim 5,

wherein the power transmission device includes a memory circuit in which the capacitance value of the variable capacitor for setting the resonance frequency of the first resonance coil on the basis of the resonance frequency of the second resonance coil is stored, and

wherein the memory circuit is connected to the control device.

7. A wireless power transmission system comprising a power transmission device and a power receiving device,

wherein the power transmission device comprising:

a first coil;

a first resonance coil;

a detector; and

a control device,

wherein the first coil is connected to a high-frequency power source through a coupler,

wherein the first resonance coil is electromagnetically coupled with the first coil and is connected to a variable capacitor,

wherein the detector detects intensity of an S11 parameter output from the coupler,

wherein the control device has a function of changing a capacitance value of the variable capacitor and an oscillation frequency of a signal output from the high-frequency power source, sets the capacitance value of the variable capacitor to 0, sets a frequency at which the intensity of the S11 parameter is changed at the time when the oscillation frequency of the signal output from the high-frequency power source is changed under a condition that the capacitance value of the variable capacitor is 0, as a resonance frequency of a second resonance coil, sets a resonance frequency of the first resonance coil after the capacitance value of the variable capacitor is set in accordance with the resonance frequency of the second resonance coil, and sets a frequency at which the intensity of the S11 parameter is changed at the time when the oscillation frequency of the signal output from the high-frequency power source is changed under a condition that the capacitance value of the variable capacitor is set to a capacitance value based on the resonant frequency of the second resonance coil, as the oscillation frequency of the signal output from the high-frequency power source, and

wherein the power receiving device includes the second resonance coil which causes electromagnetic resonance with the first resonance coil and is connected to a capacitor and a second coil which is electromagnetically coupled with the second resonance coil and is connected to a load.

8. The wireless power transmission system according to claim 7,

wherein the power transmission device includes a memory circuit in which the capacitance value of the variable capacitor for setting the resonance frequency of the first resonance coil on the basis of the resonance frequency of the second resonance coil is stored, and

wherein the memory circuit is connected to the control device.

9. A wireless power transmission system comprising a power transmission device and a power receiving device,

wherein the power transmission device comprising:

a first coil;

a first resonance coil;

a detector; and

a control device,

wherein the first coil is connected to a high-frequency power source through a coupler,

wherein the first resonance coil is electromagnetically coupled with the first coil and is connected to a variable capacitor,

wherein the power receiving device includes a second resonance coil which causes electromagnetic resonance with the first resonance coil and is connected to a capacitor and a second coil which is electromagnetically coupled with the second resonance coil and is connected to a load.

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

wherein the power transmission device includes a memory circuit in which a capacitance value of the variable capacitor for setting a resonance frequency of the first resonance coil on the basis of a resonance frequency of the second resonance coil is stored, and

wherein the memory circuit is connected to the control device.