IMPEDANCE MATCHING DEVICE AND CONTROL METHOD

• US 20140175896A1
• Filed: 06/07/2011
• Published: 06/26/2014
• 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 9,484,881 B2
• Time in Patent Office: Days
• 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: B60L 53/32 by charging in short intervals along the itinerary, e.g. during short stops
• 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: 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 90/14 Plug-in electric vehicles

Abstract

In an impedance matching device between a power transmission circuit and a power transmission antenna, a storage unit stores tables associated with a load value, each storing control values of a coupling coefficient between the power transmission and reception antennae. A selection unit selects a table corresponding to the load value estimated by the load value estimation unit. An adjustment direction determination unit determines the direction of a position for reading out one of the control values from the selected table. A readout position determination unit determines the position for reading out the control value from the selected table based on the direction and a predetermined step width for shifting the position for reading out the control value. A circuit selection unit electrically connects a matching circuit or the through circuit. A control value output unit outputs the control value at the determined position to the selected circuit.

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 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 phase determination unit configured to compare a phase of the incident wave voltage to a phase of the reflective wave voltage to determine which one of the phases is behind or ahead of the other phase;

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 store tables each associated with the value of the load, each of the tables previously storing control values in ascending or descending order of a coupling coefficient corresponding thereto between the power transmission antenna and the power reception antenna, 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 selection unit configured to select one of the tables corresponding to the value of the load estimated by the load value estimation unit;

an adjustment direction determination unit configured to determine, on a basis of the determination by the phase determination unit, a direction of a position for reading out one of the control values from the selected table, the direction indicating whether to select a control value corresponding to a larger coupling coefficient than the coupling coefficient corresponding to the present control value or to select a control value corresponding to a smaller coupling coefficient than the coupling coefficient corresponding to the present control value;

a readout position determination unit configured to determine the position for reading out the control value from the selected table based on the direction and a predetermined step width for shifting the position for reading out the control value;

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 determined position; and

a control value output unit configured to output the control value at the determined position to the circuit selected by the circuit selection unit.

2. The impedance matching device according to claim 1,

wherein each of the tables previously stores the control values and flag information in ascending or descending order of the coupling coefficient corresponding thereto, the flag information indicating either the first matching circuit or the second matching circuit to which each of the control values is applied, and

wherein the circuit selection unit electrically connect one of the first matching circuit, the second matching circuit and the through circuit based on the flag information corresponding to the determined position.

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.

4. The impedance matching device according to claim 1,

wherein the adjustment direction determination unit determines the direction to select a control value corresponding to a larger coupling coefficient than the coupling coefficient corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is behind the phase of the incident wave voltage, and determines the direction to select a control value corresponding to a smaller coupling coefficient than the coupling coefficient corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is ahead of the phase of the incident wave voltage.

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

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 step width determination unit configured to determine the step width based on the reflection-coefficient-absolute-value equivalent value.

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

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 phase determination unit determines which one of the phases is behind or ahead of the other phase only when the reflection-coefficient-absolute-value equivalent value is larger than a predetermined value.

11. 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.

14. 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.

15. The impedance matching device according to claim 2,

wherein the adjustment direction determination unit determines the direction to select a control value corresponding to a larger coupling coefficient than the coupling coefficient corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is behind the phase of the incident wave voltage, and determines the direction to select a control value corresponding to a smaller coupling coefficient than the coupling coefficient corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is ahead of the phase of the incident wave voltage.

16. The impedance matching device according to claim 3,

wherein the adjustment direction determination unit determines the direction to select a control value corresponding to a larger coupling coefficient than the coupling coefficient corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is behind the phase of the incident wave voltage, and determines the direction to select a control value corresponding to a smaller coupling coefficient than the coupling coefficient corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is ahead of the phase of the incident wave voltage.

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

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 step width determination unit configured to determine the step width based on the reflection-coefficient-absolute-value equivalent value.

5. 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 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 phase determination unit configured to compare a phase of the incident wave voltage to a phase of the reflective wave voltage to determine which one of the phases is behind or ahead of the other phase;

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 store tables each associated with the coupling coefficient, each of the tables previously storing control values in ascending or descending order of a value of a load of a circuit corresponding thereto, 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 circuit being connected to the power reception antenna and consuming the transmitted electric power;

a selection unit configured to select one of the tables corresponding to the coupling coefficient estimated by the coupling coefficient estimation unit;

an adjustment direction determination unit configured to determine, on a basis of the determination by the phase determination unit, a direction of a position for reading out one of the control values from the selected table, the direction indicating whether to select a control value corresponding to a larger value of the load than the value of the load corresponding to the present control value or to select a control value corresponding to a smaller value of the load than the value of the load corresponding to the present control value;

a readout position determination unit configured to determine the position for reading out the control value from the selected table based on the direction and a predetermined step width for shifting the position for reading out the control value;

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 determined position; and

a control value output unit configured to output the control value at the determined position to the circuit selected by the circuit selection unit.

6. The impedance matching device according to claim 5,

wherein each of the tables previously stores the control values and flag information in ascending or descending order of the value of the load corresponding thereto, the flag information indicating either the first matching circuit or the second matching circuit to which each of the control values is applied, and

wherein the circuit selection unit electrically connect one of the first matching circuit, the second matching circuit and the through circuit based on the flag information corresponding to the determined position.

7. 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 the coupling coefficient between the power transmission antenna and the power reception antenna is fixed.

8. The impedance matching device according to claim 5,

wherein the adjustment direction determination unit determines the direction to select a control value corresponding to a smaller value of the load than the value of the load corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is behind the phase of the incident wave voltage, and determines the direction to select a control value corresponding to a larger value of the load than the value of the load corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is ahead of the phase of the incident wave voltage.

17. The impedance matching device according to claim 6,

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 the coupling coefficient between the power transmission antenna and the power reception antenna is fixed.

18. The impedance matching device according to claim 6,

wherein the adjustment direction determination unit determines the direction to select a control value corresponding to a smaller value of the load than the value of the load corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is behind the phase of the incident wave voltage, and determines the direction to select a control value corresponding to a larger value of the load than the value of the load corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is ahead of the phase of the incident wave voltage.

19. The impedance matching device according to claim 7,

wherein the adjustment direction determination unit determines the direction to select a control value corresponding to a smaller value of the load than the value of the load corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is behind the phase of the incident wave voltage, and determines the direction to select a control value corresponding to a larger value of the load than the value of the load corresponding to the present control value if the phase determination unit determines that the phase of the reflective wave voltage is ahead of the phase of the incident wave voltage.

12. 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 store tables each associated with a value of a load of a circuit, each of the tables previously storing control values in ascending or descending order of a coupling coefficient corresponding thereto between the power transmission antenna and the power reception antenna, 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 circuit being connected to the power reception antenna and consuming the transmitted electric power;

the control method comprising;

an incident-wave/reflective-wave extraction process for extracting 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 phase determination process for comparing a phase of the incident wave voltage to a phase of the reflective wave voltage to determine which one of the phases is behind or ahead of the other phase;

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

a selection process for selecting one of the tables corresponding to the value of the load estimated through the load value estimation process;

an adjustment direction determination process for determining, on a basis of the determination through the phase determination process, a direction of a position for reading out one of the control values from the selected table, the direction indicating whether to select a control value corresponding to a larger coupling coefficient than the coupling coefficient corresponding to the present control value or to select a control value corresponding to a smaller coupling coefficient than the coupling coefficient corresponding to the present control value;

a readout position determination process for determining the position for reading out the control value from the selected table based on the direction and a predetermined step width for shifting the position for reading out the control value;

a circuit selection process for electrically connecting one of the first matching circuit, the second matching circuit and the through circuit based on the determined position; and

a control value output process for outputting the control value at the determined position to the circuit selected through the circuit selection process.

13. 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 store tables each associated with a coupling coefficient between the power transmission antenna and the power reception antenna, each of the tables previously storing control values in ascending or descending order of a value of a load of a circuit corresponding thereto, 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 circuit being connected to the power reception antenna and consuming the transmitted electric power;

the control method comprising;

an incident-wave/reflective-wave extraction process for extracting 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 phase determination process for comparing a phase of the incident wave voltage to a phase of the reflective wave voltage to determine which one of the phases is behind or ahead of the other phase;

a coupling coefficient estimation process for estimating the coupling coefficient;

a selection process for selecting one of the tables corresponding to the coupling coefficient estimated through the coupling coefficient estimation process;

an adjustment direction determination process for determining, on a basis of the determination through the phase determination process, a direction of a position for reading out one of the control values from the selected table, the direction indicating whether to select a control value corresponding to a larger value of the load than the value of the load corresponding to the present control value or to select a control value corresponding to a smaller value of the load than the value of the load corresponding to the present control value;

a readout position determination process for determining the position for reading out the control value from the selected table based on the direction and a predetermined step width for shifting the position for reading out the control value;

a circuit selection process for electrically connecting one of the first matching circuit, the second matching circuit and the through circuit based on the determined position; and

a control value output process for outputting the control value at the determined position to the circuit selected through the circuit selection process.