IMPEDANCE MATCHING DEVICE AND CONTROL METHOD

• US 20140191819A1
• Filed: 06/07/2011
• Published: 07/10/2014
• Est. Priority Date: 06/07/2011
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Pioneer Corporation
• Inventors: Suzuki, Masami
• Granted Patent: US 9,331,663 B2
• Time in Patent Office: Days
• US Class Current: 333/17.3
• 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 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance
• CPC Class Codes: H04B 5/0037 for power transfer
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

In an impedance matching device, a storage unit stores a control value representing a load value and a value equivalent to input impedance in advance. The control value identifies inductance and capacitance values matching a predetermined impedance value by use of either a first or second matching circuit. An impedance estimation unit estimates input impedance of the power transmission antenna. The load value estimation unit estimates load value of a circuit connected to a power reception antenna and consuming transmitted electric power. A circuit selection unit electrically connects the first matching circuit, the second matching circuit, or a through circuit per the load value and the input impedance equivalent value. A control value output unit reads out the control value stored in the storage unit based on the load value and the input impedance equivalent value, and outputs the control value to the circuit selected by the circuit selection unit.

Claims

1. An impedance matching device included in a wireless electric power transmission system transmitting electric power by coupling a power transmission antenna with a power reception antenna through an electromagnetic field, the impedance matching device being provided between a power transmission circuit and the power transmission antenna, the impedance matching device comprising:

an input impedance estimation unit configured to estimate an input impedance equivalent value corresponding to input impedance of the power transmission antenna or a value equivalent thereto;

a first matching circuit configured to include a variable inductor element and a variable capacitor element, the variable inductor element being connected in series between the power transmission circuit and the power transmission antenna, the variable capacitor element being connected in parallel closer to the power transmission antenna than the variable inductor element;

a second matching circuit configured to include a variable inductor element and a variable capacitor element, the variable inductor element being connected in series between the power transmission circuit and the power transmission antenna, the variable capacitor element being connected in parallel closer to the power transmission circuit than the variable inductor element;

a through circuit connected in series between the power transmission circuit and the power transmission antenna;

a load value estimation unit configured to estimate a value of a load of a circuit in which the transmitted electric power is consumed, the circuit being connected to the power reception antenna;

a storage unit configured to previously store control values each associated with the value of the load and the input impedance equivalent value, each of the control values corresponding to an inductance value and a capacitance value each needed for matching to a predetermined impedance value by use of the first matching circuit or the second matching circuit;

a circuit selection unit configured to electrically connect one of the first matching circuit, the second matching circuit and the through circuit based on the estimated value of the load and the estimated input impedance equivalent value; and

a control value output unit configured to read out one of the control values stored in the storage unit based on the estimated value of the load and the estimated input impedance equivalent value, and to output the control value to the circuit selected by the circuit selection unit.

2. The impedance matching device according to claim 1,

wherein the storage unit previously stores the control values and flag information each pair of which associated with the value of the load and the input impedance equivalent value, the flag information indicating either the first matching circuit or the second matching circuit to which the control value is applied, and

wherein the circuit selection unit electrically connects either one of the first matching circuit or the second matching circuit based on the flag information determined from the estimated value of the load and the estimated input impedance equivalent value.

3. The impedance matching device according to claim 1,

wherein each of the control values is determined based on a locus of variation of impedance inputted from the power transmission circuit to the power transmission antenna in a condition that coupling state between the power transmission antenna and the power reception antenna is changed while the value of the load of the circuit is fixed.

7. The impedance matching device according to claim 1, further comprising:

an incident-wave/reflective-wave extraction unit configured to extract incident wave voltage corresponding to an output signal from the power transmission circuit and reflective wave voltage corresponding to a signal reflected from the power transmission antenna;

a reflection coefficient calculation unit configured to calculate a reflection-coefficient-absolute-value equivalent value based on the incident wave voltage and the reflective wave voltage, the reflection-coefficient-absolute-value equivalent value indicating an absolute value of the reflection coefficient or a value equivalent thereto; and

a phase difference calculation unit configured to compare a phase of the incident wave voltage to a phase of the reflective wave voltage and to calculate a phase difference between the phases,

wherein the input impedance estimation unit estimates the reflection-coefficient-absolute-value equivalent value and the phase difference as the input impedance equivalent value.

8. The impedance matching device according to claim 1, further comprising:

an incident-wave/reflective-wave extraction unit configured to extract incident wave voltage corresponding to an output signal from the power transmission circuit and reflective wave voltage corresponding to a signal reflected from the power transmission antenna; and

a reflection coefficient calculation unit configured to calculate a reflection-coefficient-absolute-value equivalent value based on the incident wave voltage and the reflective wave voltage, the reflection-coefficient-absolute-value equivalent value indicating an absolute value of the reflection coefficient or a value equivalent thereto,

wherein the circuit selection unit selects the through circuit if the reflection-coefficient-absolute-value equivalent value is equal to or smaller than a predetermined value.

9. The impedance matching device according to claim 1,

wherein the control value is quantized such that the larger an absolute value of a reflection coefficient is, the shorter the quantizing interval becomes.

12. The impedance matching device according to claim 2,

wherein each of the control values is determined based on a locus of variation of impedance inputted from the power transmission circuit to the power transmission antenna in a condition that coupling state between the power transmission antenna and the power reception antenna is changed while the value of the load of the circuit is fixed.

14. The impedance matching device according to claim 2, further comprising:

an incident-wave/reflective-wave extraction unit configured to extract incident wave voltage corresponding to an output signal from the power transmission circuit and reflective wave voltage corresponding to a signal reflected from the power transmission antenna;

a reflection coefficient calculation unit configured to calculate a reflection-coefficient-absolute-value equivalent value based on the incident wave voltage and the reflective wave voltage, the reflection-coefficient-absolute-value equivalent value indicating an absolute value of the reflection coefficient or a value equivalent thereto; and

a phase difference calculation unit configured to compare a phase of the incident wave voltage to a phase of the reflective wave voltage and to calculate a phase difference between the phases,

wherein the input impedance estimation unit estimates the reflection-coefficient-absolute-value equivalent value and the phase difference as the input impedance equivalent value.

15. The impedance matching device according to claim 3, further comprising:

an incident-wave/reflective-wave extraction unit configured to extract incident wave voltage corresponding to an output signal from the power transmission circuit and reflective wave voltage corresponding to a signal reflected from the power transmission antenna;

a reflection coefficient calculation unit configured to calculate a reflection-coefficient-absolute-value equivalent value based on the incident wave voltage and the reflective wave voltage, the reflection-coefficient-absolute-value equivalent value indicating an absolute value of the reflection coefficient or a value equivalent thereto; and

a phase difference calculation unit configured to compare a phase of the incident wave voltage to a phase of the reflective wave voltage and to calculate a phase difference between the phases,

wherein the input impedance estimation unit estimates the reflection-coefficient-absolute-value equivalent value and the phase difference as the input impedance equivalent value.

19. The impedance matching device according to claim 2, further comprising:

an incident-wave/reflective-wave extraction unit configured to extract incident wave voltage corresponding to an output signal from the power transmission circuit and reflective wave voltage corresponding to a signal reflected from the power transmission antenna; and

a reflection coefficient calculation unit configured to calculate a reflection-coefficient-absolute-value equivalent value based on the incident wave voltage and the reflective wave voltage, the reflection-coefficient-absolute-value equivalent value indicating an absolute value of the reflection coefficient or a value equivalent thereto,

wherein the circuit selection unit selects the through circuit if the reflection-coefficient-absolute-value equivalent value is equal to or smaller than a predetermined value.

20. The impedance matching device according to claim 3, further comprising:

an incident-wave/reflective-wave extraction unit configured to extract incident wave voltage corresponding to an output signal from the power transmission circuit and reflective wave voltage corresponding to a signal reflected from the power transmission antenna; and

a reflection coefficient calculation unit configured to calculate a reflection-coefficient-absolute-value equivalent value based on the incident wave voltage and the reflective wave voltage, the reflection-coefficient-absolute-value equivalent value indicating an absolute value of the reflection coefficient or a value equivalent thereto,

wherein the circuit selection unit selects the through circuit if the reflection-coefficient-absolute-value equivalent value is equal to or smaller than a predetermined value.

4. An impedance matching device included in a wireless electric power transmission system transmitting electric power by coupling a power transmission antenna with a power reception antenna through an electromagnetic field, the impedance matching device being provided between a power transmission circuit and the power transmission antenna, the impedance matching device comprising:

an input impedance estimation unit configured to estimate an input impedance equivalent value corresponding to input impedance of the power transmission antenna or a value equivalent thereto;

a first matching circuit configured to include a variable inductor element and a variable capacitor element, the variable inductor element being connected in series between the power transmission circuit and the power transmission antenna, the variable capacitor element being connected in parallel closer to the power transmission antenna than the variable inductor element;

a second matching circuit configured to include a variable inductor element and a variable capacitor element, the variable inductor element being connected in series between the power transmission circuit and the power transmission antenna, the variable capacitor element being connected in parallel closer to the power transmission circuit than the variable inductor element;

a through circuit connected in series between the power transmission circuit and the power transmission antenna;

a coupling coefficient estimation unit configured to estimate a coupling coefficient between the power transmission antenna and the power reception antenna;

a storage unit configured to previously store control values each associated with the coupling coefficient and the input impedance equivalent value, each of the control values corresponding to an inductance value and a capacitance value each needed for matching to a predetermined impedance value by use of the first matching circuit or the second matching circuit;

a circuit selection unit configured to electrically connect one of the first matching circuit, the second matching circuit and the through circuit based on the estimated coupling coefficient and the estimated input impedance equivalent value; and

a control value output unit configured to read out one of the control values stored in the storage unit based on the estimated coupling coefficient and the estimated input impedance equivalent value, and to output the control value to the circuit selected by the circuit selection unit.

5. The impedance matching device according to claim 4,

wherein the storage unit previously stores the control values and flag information each pair of which associated with the coupling coefficient and the input impedance equivalent value, the flag information indicating either the first matching circuit or the second matching circuit to which the control value is applied, and

wherein the circuit selection unit electrically connect either one of the first matching circuit or the second matching circuit based on the flag information determined from the estimated coupling coefficient and the estimated input impedance equivalent value.

6. The impedance matching device according to claim 4,

wherein each of the control values is determined based on a locus of variation of impedance inputted from the power transmission circuit to the power transmission antenna in a condition that the value of the load of the circuit is changed while coupling state between the power transmission antenna and the power reception antenna is fixed.

13. The impedance matching device according to claim 5,

wherein each of the control values is determined based on a locus of variation of impedance inputted from the power transmission circuit to the power transmission antenna in a condition that the value of the load of the circuit is changed while coupling state between the power transmission antenna and the power reception antenna is fixed.

16. The impedance matching device according to claim 4, further comprising:

an incident-wave/reflective-wave extraction unit configured to extract incident wave voltage corresponding to an output signal from the power transmission circuit and reflective wave voltage corresponding to a signal reflected from the power transmission antenna;

a reflection coefficient calculation unit configured to calculate a reflection-coefficient-absolute-value equivalent value based on the incident wave voltage and the reflective wave voltage, the reflection-coefficient-absolute-value equivalent value indicating an absolute value of the reflection coefficient or a value equivalent thereto; and

a phase difference calculation unit configured to compare a phase of the incident wave voltage to a phase of the reflective wave voltage and to calculate a phase difference between the phases,

wherein the input impedance estimation unit estimates the reflection-coefficient-absolute-value equivalent value and the phase difference as the input impedance equivalent value.

17. The impedance matching device according to claim 5, further comprising:

an incident-wave/reflective-wave extraction unit configured to extract incident wave voltage corresponding to an output signal from the power transmission circuit and reflective wave voltage corresponding to a signal reflected from the power transmission antenna;

a reflection coefficient calculation unit configured to calculate a reflection-coefficient-absolute-value equivalent value based on the incident wave voltage and the reflective wave voltage, the reflection-coefficient-absolute-value equivalent value indicating an absolute value of the reflection coefficient or a value equivalent thereto; and

a phase difference calculation unit configured to compare a phase of the incident wave voltage to a phase of the reflective wave voltage and to calculate a phase difference between the phases,

wherein the input impedance estimation unit estimates the reflection-coefficient-absolute-value equivalent value and the phase difference as the input impedance equivalent value.

18. The impedance matching device according to claim 6, further comprising:

an incident-wave/reflective-wave extraction unit configured to extract incident wave voltage corresponding to an output signal from the power transmission circuit and reflective wave voltage corresponding to a signal reflected from the power transmission antenna;

a reflection coefficient calculation unit configured to calculate a reflection-coefficient-absolute-value equivalent value based on the incident wave voltage and the reflective wave voltage, the reflection-coefficient-absolute-value equivalent value indicating an absolute value of the reflection coefficient or a value equivalent thereto; and

a phase difference calculation unit configured to compare a phase of the incident wave voltage to a phase of the reflective wave voltage and to calculate a phase difference between the phases,

wherein the input impedance estimation unit estimates the reflection-coefficient-absolute-value equivalent value and the phase difference as the input impedance equivalent value.

10. A control method executed by an impedance matching device included in a wireless electric power transmission system transmitting electric power by coupling a power transmission antenna with a power reception antenna through an electromagnetic field, the impedance matching device being provided between a power transmission circuit and the power transmission antenna, the impedance matching device comprising:

a first matching circuit configured to include a variable inductor element and a variable capacitor element, the variable inductor element being connected in series between the power transmission circuit and the power transmission antenna, the variable capacitor element being connected in parallel closer to the power transmission antenna than the variable inductor element;

a second matching circuit configured to include a variable inductor element and a variable capacitor element, the variable inductor element being connected in series between the power transmission circuit and the power transmission antenna, the variable capacitor element being connected in parallel closer to the power transmission circuit than the variable inductor element;

a through circuit connected in series between the power transmission circuit and the power transmission antenna; and

a storage unit configured to previously store control values each associated with a value of a load of a circuit in which the transmitted electric power is consumed and an input impedance equivalent value, each of the control values corresponding to an inductance value and a capacitance value each needed for matching to a predetermined impedance value by use of the first matching circuit or the second matching circuit, the input impedance equivalent value corresponding to input impedance of the power transmission antenna or a value equivalent thereto, the circuit being connected to the power reception antenna,

the control method comprising;

an input impedance estimation process for estimating the input impedance equivalent value;

a load value estimation process for estimating the value of the load;

a circuit selection process for electrically connecting one of the first matching circuit, the second matching circuit and the through circuit based on the estimated value of the load and the estimated input impedance equivalent value; and

a control value output process for reading out one of the control values stored in the storage unit based on the estimated value of the load and the estimated input impedance equivalent value, and for outputting the control value to the circuit selected in the circuit selection process.

11. A control method executed by an impedance matching device included in a wireless electric power transmission system transmitting electric power by coupling a power transmission antenna with a power reception antenna through an electromagnetic field, the impedance matching device being provided between a power transmission circuit and the power transmission antenna, the impedance matching device comprising:

a first matching circuit configured to include a variable inductor element and a variable capacitor element, the variable inductor element being connected in series between the power transmission circuit and the power transmission antenna, the variable capacitor element being connected in parallel closer to the power transmission antenna than the variable inductor element;

a second matching circuit configured to include a variable inductor element and a variable capacitor element, the variable inductor element being connected in series between the power transmission circuit and the power transmission antenna, the variable capacitor element being connected in parallel closer to the power transmission circuit than the variable inductor element;

a through circuit connected in series between the power transmission circuit and the power transmission antenna; and

a storage unit configured to previously store control values each associated with a coupling coefficient between the power transmission antenna and the power reception antenna and an input impedance equivalent value, each of the control values corresponding to an inductance value and a capacitance value each needed for matching to a predetermined impedance value by use of the first matching circuit or the second matching circuit, the input impedance equivalent value corresponding to input impedance of the power transmission antenna or a value equivalent thereto,

the control method comprising;

an input impedance estimation process for estimating the input impedance equivalent value;

a coupling state estimation process for estimating the coupling coefficient;

a circuit selection process for electrically connecting one of the first matching circuit, the second matching circuit and the through circuit based on the estimated coupling coefficient and the estimated input impedance equivalent value; and

a control value output process for reading out one of the control values stored in the storage unit based on the estimated coupling coefficient and the estimated input impedance equivalent value, and for outputting the control value to the circuit selected in the circuit selection process.