RESONANT FREQUENCY CONTROL METHOD, ELECTRIC POWER TRANSMITTING DEVICE, ELECTRIC POWER RECEIVING DEVICE IN MAGNETIC RESONANT TYPE POWER TRANSMISSION SYSTEM

• US 20130015720A1
• Filed: 07/31/2012
• Published: 01/17/2013
• Est. Priority Date: 02/10/2010
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: SHIMOKAWA, Satoshi, UCHIDA, Akiyoshi, TAGUCHI, Masakazu
• Granted Patent: US 9,634,493 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: G06G 7/18 for integration or differentiation; for forming integrals G06G7/19 takes precedence
• 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: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode

Abstract

In a resonant frequency control method in a magnetic field resonant coupling type power transmission system transmitting an electric power from a power transmitting coil to a power receiving coil using magnetic field resonance, a high-speed, accurate and real-time adjustment of the resonant frequency of a coil is realized. The phase of a voltage supplied to a power transmitting coil and the phase of a current that flows in the power transmitting coil or a power receiving coil is detected and the resonant frequency of the power transmitting coil or the power receiving coil is varied such that the phase difference between them becomes a target value.

Claims

1. A resonant frequency control method in a magnetic field resonant coupling type power transmission system transmitting an electric power from a power transmitting coil to a power receiving coil using magnetic field resonance, comprising:

detecting a phase of a voltage supplied to the power transmitting coil and a phase of a current that flows in the power transmitting coil or the power receiving coil, and varying a resonant frequency of the power transmitting coil or the power receiving coil such that phase difference between them becomes a target value.

2. The resonant frequency control method in the magnetic field resonant coupling type power transmission system according to claim 1, wherein:

the power transmitting coil comprises a power supplying coil to which an alternating-current power supply is connected, and a power transmitting resonant coil closely coupled electromagnetically with the power supplying coil;

the power receiving coil comprises a power receiving resonant coil, and a power drawing coil closely coupled electromagnetically with the power receiving resonant coil;

a resonant frequency of the power transmitting resonant coil is varied such that a phase difference between a voltage of the alternating-current power supply and a current of the power transmitting resonant coil becomes a target value β

; and

a resonant frequency of the power receiving coil is varied such that a phase difference between the voltage of the alternating-current power supply and a current of the power receiving resonant coil becomes a target value ((β

−

π

/2).

3. The resonant frequency control method in the magnetic field resonant coupling type power transmission system according to claim 2, wherein:

the target value β

is −

π

.

4. The resonant frequency control method in the magnetic field resonant coupling type power transmission system according to claim 1, wherein:

when a degree of coupling between the power transmitting coil and the power receiving coil increases and a diphasic property appears, a resonant frequency of the power transmitting coil or the power receiving coil is varied such that a peak of a current appears at a frequency of the alternating-current power supply.

5. The resonant frequency control method in the magnetic field resonant coupling type power transmission system according to claim 1, wherein:

the power transmitting coil comprises a power supplying coil to which an alternating-current power supply is connected, and a power transmitting resonant coil closely coupled electromagnetically with the power supplying coil;

the power receiving coil comprises a power receiving resonant coil, and a power drawing coil closely coupled electromagnetically with the power receiving resonant coil;

when a degree of coupling between the power transmitting coil and the power receiving coil increases and a diphasic property appears,

a resonant frequency of the power transmitting resonant coil is varied such that a phase difference between a voltage of the alternating-current power supply and a current of the power transmitting resonant coil becomes a target value β

; and

a resonant frequency of the power receiving coil is varied such that a phase difference between the voltage of the alternating-current power supply and a current of the power receiving resonant coil becomes a target value (β

−

π

).

6. A magnetic field resonant type power transmission device transmitting an electric power from a power transmitting coil to a power receiving coil using magnetic field resonance, comprising:

a phase detection unit configured to detect a phase of a voltage supplied to the power transmitting coil and a phase of a current that flows in the power transmitting coil or the power receiving coil; and

a resonant frequency control unit configured to vary a resonant frequency of the power transmitting coil or the power receiving coil such that a phase difference between the detected phases becomes a target value.

7. A magnetic field resonant coupling type power transmission device transmitting an electric power from a power transmitting coil to a power receiving coil using magnetic field resonant, comprising:

a power transmitting phase detection unit configured to detect a phase of a voltage supplied to the power transmitting coil and a phase of a current that flows in the power transmitting coil;

a power transmitting resonant frequency control unit configured to vary a resonant frequency of the power transmitting coil such that a phase difference between the detected phases becomes a target value.

8. The power transmission device in the magnetic field resonant coupling type power transmission device according to claim 7, wherein:

the power transmitting coil comprises a power supplying coil to which an alternating-current power supply is connected, and a power transmitting resonant coil closely coupled electromagnetically with the power supplying coil; and

the power transmitting resonant frequency control unit comprises a target value setting unit configured to set and store the target value; and

a feedback control unit configured to vary a resonant frequency of the power transmitting resonant coil such that a phase difference between a voltage of the alternating-current power supply and a current of the power transmitting resonant coil becomes the set target value.

9. The power transmission device in the magnetic field resonant coupling type power transmission device according to claim 8, wherein:

the feedback control unit comprises;

a phase comparison unit configured to compare the phase of the voltage and the phase of the current, and to output a phase difference being a difference between them;

a calculation unit configured to calculate a phase difference that the phase comparison unit outputs and a target value set by the target value setting unit; and

a driver configured to drive to as to vary an inductance or a capacitance in the power transmitting resonant coil. 20

10. The power transmission device in the magnetic field resonant coupling type power transmission device according to claim 8, wherein:

the target value setting unit sets −

π

as the target value.

11. The power transmission device in the magnetic field resonant coupling type power transmission device according to claims 7, comprising:

a phase information transmission unit configured to transmit information about a phase of a voltage supplied to the power transmitting coil wirelessly.

12. A power receiving device in a magnetic field resonant coupling type power transmission device transmitting an electric power from a power transmitting coil to a power receiving coil using magnetic field resonance, comprising:

a phase information reception unit configured to receive information about a phase of a voltage supplied to the power transmitting coil;

a power receiving phase detection unit configured to detect a phase of a current that flows in the power receiving coil; and

a power receiving resonant frequency control unit configured to vary a resonant frequency of the power receiving coil such that a phase difference between a phase of a voltage received by the phase information reception unit and a detected phase of the current becomes a target value.

13. The power receiving device in the magnetic field resonant coupling type power transmission device according to claim 12, wherein

the power receiving coil comprises a power drawing coil, and a power drawing coil closely coupled electromagnetically with the power drawing coil;

and

the power receiving resonant frequency control unit comprises

a target value setting unit configured to set and store the target value; and

a feedback control unit configured to vary a resonant frequency of the power receiving resonant coil such that a phase difference between a phase of a voltage received by the phase information reception unit and a detected phase of the current becomes the target value.

14. The power receiving device in the magnetic field resonant coupling type power transmission device according to claim 13, wherein:

the feedback control unit comprises;

a phase comparison unit configured to compare the phase of the voltage and the phase of the current, and to output a phase difference being the difference between them;

a calculation unit configured to calculate a phase difference that the phase comparison unit outputs and a target value set by the target value setting unit; and

a driver configured to drive to as to vary an inductance or a capacitance in the power receiving resonant coil.

15. The power receiving device in the magnetic field resonant coupling type power transmission device according to claim 13, wherein:

the target value setting unit sets −

3π

/2 as the target value.

16. The power receiving device in the magnetic field resonant coupling type power transmission device according to claim 13, wherein:

the target value setting unit switches and sets the target value to −

2π

when a degree of coupling between the power transmitting coil and the power receiving coil increases and a diphasic property appears.